Fix offenses to non-production code

- Lint/AmbiguousBlockAssociation
- Lint/AmbiguousOperatorPrecedence
- Lint/EmptyBlock
- Lint/RedundantSplatExpansion
- Lint/RedundantStringCoercion
- Lint/SymbolConversion
- Lint/UnusedBlockArgument
- Style/BlockDelimiters
- Style/CommentAnnotation
- Style/EachForSimpleLoop
- Style/EmptyMethod
- Style/ExpandPathArguments
- Style/FileWrite
- Style/GlobalStdStream (UNSAFE)
- Style/HashEachMethods (UNSAFE)
- Style/NestedParenthesizedCalls
- Style/NilComparison
- Style/NumericLiteralPrefix (manually fixed)
- Style/ParallelAssignment
- Style/PreferredHashMethods (UNSAFE)
- Style/RedundantInterpolation (UNSAFE)
- Style/RedundantParentheses (UNSAFE)
- Style/RegexpLiteral
- Style/RescueStandardError
- Style/SpecialGlobalVars (UNSAFE)
- Style/SymbolProc (UNSAFE)
- Style/ZeroLengthPredicate (UNSAFE)

72 files changed, 272 insertions, 318 deletions

diff --git a/.rubocop.yml b/.rubocop.yml
index 32a50a30..510c1b4b 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -19,5 +19,8 @@ Layout/CommentIndentation:
 Layout/ExtraSpacing:
   AllowBeforeTrailingComments: true
 
+Lint:
+  Enabled: true
+
 Style:
   Enabled: true
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 67848b74..f17b6eda 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -29,6 +29,87 @@ Layout/HeredocIndentation:
     - 'lib/axlsx/drawing/vml_shape.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
+Lint/AmbiguousOperatorPrecedence:
+  Exclude:
+    - 'lib/axlsx/drawing/area_series.rb'
+    - 'lib/axlsx/drawing/line_series.rb'
+    - 'lib/axlsx/drawing/pie_series.rb'
+    - 'lib/axlsx/workbook/worksheet/dimension.rb'
+    - 'lib/axlsx/workbook/worksheet/sheet_protection.rb'
+    - 'lib/axlsx/workbook/worksheet/worksheet.rb'
+
+# This cop supports unsafe autocorrection (--autocorrect-all).
+# Configuration parameters: AllowSafeAssignment.
+Lint/AssignmentInCondition:
+  Exclude:
+    - 'lib/axlsx/drawing/area_chart.rb'
+    - 'lib/axlsx/drawing/line_chart.rb'
+    - 'lib/axlsx/workbook/shared_strings_table.rb'
+
+# This cop supports unsafe autocorrection (--autocorrect-all).
+Lint/BooleanSymbol:
+  Exclude:
+    - 'lib/axlsx/stylesheet/font.rb'
+    - 'lib/axlsx/util/validators.rb'
+    - 'lib/axlsx/workbook/worksheet/cell.rb'
+    - 'lib/axlsx/workbook/worksheet/rich_text_run.rb'
+    - 'test/util/tc_validators.rb'
+    - 'test/workbook/tc_workbook.rb'
+
+# This cop supports unsafe autocorrection (--autocorrect-all).
+Lint/DisjunctiveAssignmentInConstructor:
+  Exclude:
+    - 'lib/axlsx/drawing/num_data_source.rb'
+
+# Configuration parameters: IgnoreLiteralBranches, IgnoreConstantBranches.
+Lint/DuplicateBranch:
+  Exclude:
+    - 'lib/axlsx/workbook/worksheet/cell.rb'
+    - 'lib/axlsx/workbook/worksheet/merged_cells.rb'
+
+Lint/NonLocalExitFromIterator:
+  Exclude:
+    - 'lib/axlsx/util/validators.rb'
+
+# This cop supports safe autocorrection (--autocorrect).
+Lint/RedundantStringCoercion:
+  Exclude:
+    - 'lib/axlsx/workbook/worksheet/auto_filter/filters.rb'
+    - 'lib/axlsx/workbook/worksheet/cell.rb'
+    - 'lib/axlsx/workbook/worksheet/rich_text_run.rb'
+
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: IgnoreEmptyBlocks, AllowUnusedKeywordArguments.
+Lint/UnusedBlockArgument:
+  Exclude:
+    - 'lib/axlsx.rb'
+    - 'lib/axlsx/drawing/axes.rb'
+    - 'lib/axlsx/workbook/worksheet/pivot_table.rb'
+    - 'lib/axlsx/workbook/worksheet/sheet_view.rb'
+
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: AllowUnusedKeywordArguments, IgnoreEmptyMethods, IgnoreNotImplementedMethods.
+Lint/UnusedMethodArgument:
+  Exclude:
+    - 'lib/axlsx/package.rb'
+    - 'lib/axlsx/util/serialized_attributes.rb'
+    - 'lib/axlsx/util/validators.rb'
+
+Lint/UselessAssignment:
+  Exclude:
+    - 'lib/axlsx/workbook/worksheet/header_footer.rb'
+    - 'lib/axlsx/workbook/worksheet/sheet_protection.rb'
+
+# Configuration parameters: CheckForMethodsWithNoSideEffects.
+Lint/Void:
+  Exclude:
+    - 'lib/axlsx/drawing/title.rb'
+    - 'lib/axlsx/util/simple_typed_list.rb'
+    - 'lib/axlsx/util/storage.rb'
+    - 'lib/axlsx/workbook/worksheet/data_bar.rb'
+    - 'lib/axlsx/workbook/worksheet/pivot_table.rb'
+
+# This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: EnforcedStyle.
 # SupportedStyles: separated, grouped
 Style/AccessorGrouping:
@@ -48,16 +129,6 @@ Style/AndOr:
   Exclude:
     - 'lib/axlsx/workbook/worksheet/data_validation.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle, ProceduralMethods, FunctionalMethods, AllowedMethods, AllowedPatterns, AllowBracesOnProceduralOneLiners, BracesRequiredMethods.
-# SupportedStyles: line_count_based, semantic, braces_for_chaining, always_braces
-# ProceduralMethods: benchmark, bm, bmbm, create, each_with_object, measure, new, realtime, tap, with_object
-# FunctionalMethods: let, let!, subject, watch
-# AllowedMethods: lambda, proc, it
-Style/BlockDelimiters:
-  Exclude:
-    - 'test/benchmark.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: MinBranchesCount.
 Style/CaseLikeIf:
@@ -98,10 +169,6 @@ Style/CommentAnnotation:
     - 'lib/axlsx/drawing/axis.rb'
     - 'lib/axlsx/drawing/chart.rb'
     - 'lib/axlsx/drawing/view_3D.rb'
-    - 'test/drawing/tc_pie_series.rb'
-    - 'test/workbook/worksheet/tc_cell.rb'
-    - 'test/workbook/worksheet/tc_col.rb'
-    - 'test/workbook/worksheet/tc_comments.rb'
 
 # This cop supports unsafe autocorrection (--autocorrect-all).
 Style/ConcatArrayLiterals:
@@ -145,17 +212,6 @@ Style/Documentation:
     - 'lib/axlsx/workbook/worksheet/sheet_format_pr.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
-Style/EachForSimpleLoop:
-  Exclude:
-    - 'test/workbook/worksheet/tc_rich_text.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: compact, expanded
-Style/EmptyMethod:
-  Enabled: false
-
-# This cop supports safe autocorrection (--autocorrect).
 Style/EvalWithLocation:
   Exclude:
     - 'lib/axlsx/util/simple_typed_list.rb'
@@ -164,13 +220,11 @@ Style/EvalWithLocation:
 Style/ExpandPathArguments:
   Exclude:
     - 'axlsx.gemspec'
-    - 'test/tc_package.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 Style/FileWrite:
   Exclude:
     - 'lib/axlsx/util/zip_command.rb'
-    - 'test/benchmark.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: EnforcedStyle.
@@ -197,11 +251,6 @@ Style/FormatStringToken:
 Style/FrozenStringLiteralComment:
   Enabled: false
 
-# This cop supports unsafe autocorrection (--autocorrect-all).
-Style/GlobalStdStream:
-  Exclude:
-    - 'test/profile.rb'
-
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: MinBodyLength, AllowConsecutiveConditionals.
 Style/GuardClause:
@@ -231,8 +280,6 @@ Style/HashConversion:
 Style/HashEachMethods:
   Exclude:
     - 'lib/axlsx/workbook/worksheet/rich_text_run.rb'
-    - 'test/workbook/worksheet/tc_table_style_info.rb'
-    - 'test/workbook/worksheet/tc_worksheet.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: EnforcedStyle, EnforcedShorthandSyntax, UseHashRocketsWithSymbolValues, PreferHashRocketsForNonAlnumEndingSymbols.
@@ -280,10 +327,6 @@ Style/MethodCallWithoutArgsParentheses:
   Exclude:
     - 'lib/axlsx/package.rb'
     - 'test/benchmark.rb'
-    - 'test/drawing/tc_vml_drawing.rb'
-    - 'test/drawing/tc_vml_shape.rb'
-    - 'test/workbook/worksheet/tc_comments.rb'
-    - 'test/workbook/worksheet/tc_rich_text.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: EnforcedStyle.
@@ -340,14 +383,6 @@ Style/NegatedIf:
     - 'lib/axlsx/workbook/worksheet/worksheet.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: AllowedMethods.
-# AllowedMethods: be, be_a, be_an, be_between, be_falsey, be_kind_of, be_instance_of, be_truthy, be_within, eq, eql, end_with, include, match, raise_error, respond_to, start_with
-Style/NestedParenthesizedCalls:
-  Exclude:
-    - 'test/stylesheet/tc_styles.rb'
-    - 'test/workbook/worksheet/tc_worksheet.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: EnforcedStyle, MinBodyLength.
 # SupportedStyles: skip_modifier_ifs, always
 Style/Next:
@@ -364,10 +399,6 @@ Style/NilComparison:
     - 'lib/axlsx/drawing/view_3D.rb'
     - 'lib/axlsx/workbook/worksheet/sheet_protection.rb'
     - 'lib/axlsx/workbook/worksheet/worksheet.rb'
-    - 'test/drawing/tc_series_title.rb'
-    - 'test/drawing/tc_title.rb'
-    - 'test/workbook/worksheet/tc_page_setup.rb'
-    - 'test/workbook/worksheet/tc_worksheet.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: IncludeSemanticChanges.
@@ -379,13 +410,6 @@ Style/NonNilCheck:
     - 'lib/axlsx/workbook/worksheet/page_setup.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: EnforcedOctalStyle.
-# SupportedOctalStyles: zero_with_o, zero_only
-Style/NumericLiteralPrefix:
-  Exclude:
-    - 'test/doc_props/tc_core.rb'
-
-# This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: Strict, AllowedNumbers, AllowedPatterns.
 Style/NumericLiterals:
   MinDigits: 11
@@ -407,9 +431,6 @@ Style/NumericPredicate:
     - 'test/drawing/tc_marker.rb'
     - 'test/drawing/tc_one_cell_anchor.rb'
     - 'test/drawing/tc_two_cell_anchor.rb'
-    - 'test/rels/tc_relationships.rb'
-    - 'test/stylesheet/tc_styles.rb'
-    - 'test/tc_package.rb'
     - 'test/util/tc_simple_typed_list.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
@@ -443,7 +464,6 @@ Style/ParallelAssignment:
     - 'lib/axlsx/drawing/view_3D.rb'
     - 'lib/axlsx/package.rb'
     - 'lib/axlsx/workbook/worksheet/row.rb'
-    - 'test/rels/tc_relationships.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: AllowSafeAssignment, AllowInMultilineConditions.
@@ -485,7 +505,6 @@ Style/PerlBackrefs:
 Style/PreferredHashMethods:
   Exclude:
     - 'lib/axlsx.rb'
-    - 'test/workbook/tc_shared_strings_table.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: EnforcedStyle.
@@ -531,7 +550,6 @@ Style/RedundantInterpolation:
     - 'lib/axlsx/workbook/worksheet/pivot_table_cache_definition.rb'
     - 'lib/axlsx/workbook/worksheet/table.rb'
     - 'lib/axlsx/workbook/worksheet/worksheet.rb'
-    - 'test/content_type/tc_content_type.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 Style/RedundantParentheses:
@@ -545,7 +563,6 @@ Style/RedundantParentheses:
     - 'lib/axlsx/package.rb'
     - 'lib/axlsx/workbook/worksheet/pivot_table.rb'
     - 'lib/axlsx/workbook/worksheet/worksheet.rb'
-    - 'test/stylesheet/tc_styles.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 Style/RedundantRegexpEscape:
@@ -573,7 +590,6 @@ Style/RedundantSelf:
 Style/RegexpLiteral:
   Exclude:
     - 'lib/axlsx/workbook/worksheet/cell.rb'
-    - 'test/tc_package.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: EnforcedStyle.
@@ -581,7 +597,6 @@ Style/RegexpLiteral:
 Style/RescueStandardError:
   Exclude:
     - 'lib/axlsx.rb'
-    - 'test/workbook/worksheet/tc_date_time_converter.rb'
 
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: ConvertCodeThatCanStartToReturnNil, AllowedMethods, MaxChainLength.
@@ -621,14 +636,6 @@ Style/SoleNestedConditional:
     - 'lib/axlsx/util/validators.rb'
 
 # This cop supports unsafe autocorrection (--autocorrect-all).
-# Configuration parameters: RequireEnglish, EnforcedStyle.
-# SupportedStyles: use_perl_names, use_english_names, use_builtin_english_names
-Style/SpecialGlobalVars:
-  Exclude:
-    - 'test/benchmark.rb'
-    - 'test/profile.rb'
-
-# This cop supports unsafe autocorrection (--autocorrect-all).
 Style/StringChars:
   Exclude:
     - 'lib/axlsx/workbook/worksheet/sheet_protection.rb'
@@ -657,11 +664,6 @@ Style/StringLiteralsInInterpolation:
 Style/SymbolArray:
   EnforcedStyle: brackets
 
-# This cop supports safe autocorrection (--autocorrect).
-Style/SymbolLiteral:
-  Exclude:
-    - 'test/doc_props/tc_app.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: AllowMethodsWithArguments, AllowedMethods, AllowedPatterns, AllowComments.
 # AllowedMethods: define_method
@@ -674,11 +676,6 @@ Style/SymbolProc:
     - 'lib/axlsx/workbook/worksheet/conditional_formatting.rb'
     - 'lib/axlsx/workbook/worksheet/worksheet.rb'
     - 'lib/axlsx/workbook/worksheet/worksheet_hyperlinks.rb'
-    - 'test/doc_props/tc_app.rb'
-    - 'test/doc_props/tc_core.rb'
-    - 'test/stylesheet/tc_styles.rb'
-    - 'test/workbook/tc_shared_strings_table.rb'
-    - 'test/workbook/worksheet/tc_worksheet.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: EnforcedStyle, AllowSafeAssignment.
@@ -741,10 +738,6 @@ Style/ZeroLengthPredicate:
     - 'lib/axlsx/util/simple_typed_list.rb'
     - 'lib/axlsx/workbook/workbook.rb'
     - 'lib/axlsx/workbook/worksheet/sheet_pr.rb'
-    - 'test/rels/tc_relationships.rb'
-    - 'test/stylesheet/tc_styles.rb'
-    - 'test/tc_package.rb'
-    - 'test/util/tc_simple_typed_list.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, AllowedPatterns.
diff --git a/test/benchmark.rb b/test/benchmark.rb
index 3c0ebc95..7cbffa32 100644..100755
--- a/test/benchmark.rb
+++ b/test/benchmark.rb
@@ -1,5 +1,6 @@
 #!/usr/bin/env ruby -s
-$:.unshift "#{File.dirname(__FILE__)}/../lib"
+
+$LOAD_PATH.unshift "#{File.dirname(__FILE__)}/../lib"
 require 'axlsx'
 require 'csv'
 require 'benchmark'
@@ -9,7 +10,7 @@ input = (32..126).to_a.pack('U*').chars.to_a
 20.times { row << input.shuffle.join }
 times = 3000
 Benchmark.bmbm(30) do |x|
-  x.report('axlsx_noautowidth') {
+  x.report('axlsx_noautowidth') do
     p = Axlsx::Package.new
     p.workbook do |wb|
       wb.add_worksheet do |sheet|
@@ -20,9 +21,9 @@ Benchmark.bmbm(30) do |x|
     end
     p.use_autowidth = false
     p.serialize("example_noautowidth.xlsx")
-  }
+  end
 
-  x.report('axlsx') {
+  x.report('axlsx') do
     p = Axlsx::Package.new
     p.workbook do |wb|
       wb.add_worksheet do |sheet|
@@ -32,9 +33,9 @@ Benchmark.bmbm(30) do |x|
       end
     end
     p.serialize("example_autowidth.xlsx")
-  }
+  end
 
-  x.report('axlsx_shared') {
+  x.report('axlsx_shared') do
     p = Axlsx::Package.new
     p.workbook do |wb|
       wb.add_worksheet do |sheet|
@@ -45,9 +46,9 @@ Benchmark.bmbm(30) do |x|
     end
     p.use_shared_strings = true
     p.serialize("example_shared.xlsx")
-  }
+  end
 
-  x.report('axlsx_stream') {
+  x.report('axlsx_stream') do
     p = Axlsx::Package.new
     p.workbook do |wb|
       wb.add_worksheet do |sheet|
@@ -57,15 +58,15 @@ Benchmark.bmbm(30) do |x|
       end
     end
     s = p.to_stream()
-    File.open('example_streamed.xlsx', 'wb') { |f| f.write(s.read) }
-  }
+    File.binwrite('example_streamed.xlsx', s.read)
+  end
 
-  x.report('csv') {
+  x.report('csv') do
     CSV.open("example.csv", "wb") do |csv|
       times.times do
         csv << row
       end
     end
-  }
+  end
 end
 File.delete("example.csv", "example_streamed.xlsx", "example_shared.xlsx", "example_autowidth.xlsx", "example_noautowidth.xlsx")
diff --git a/test/content_type/tc_content_type.rb b/test/content_type/tc_content_type.rb
index c79352ff..a657f7e2 100644
--- a/test/content_type/tc_content_type.rb
+++ b/test/content_type/tc_content_type.rb
@@ -19,10 +19,10 @@ class TestContentType < Test::Unit::TestCase
     assert_equal(@doc.xpath("//xmlns:Default").size, 2, "There should be 2 default types")
 
     node = @doc.xpath(d_path % Axlsx::XML_CT).first
-    assert_equal(node["Extension"], "#{Axlsx::XML_EX}", "xml content type invalid")
+    assert_equal(node["Extension"], Axlsx::XML_EX.to_s, "xml content type invalid")
 
     node = @doc.xpath(d_path % Axlsx::RELS_CT).first
-    assert_equal(node["Extension"], "#{Axlsx::RELS_EX}", "relationships content type invalid")
+    assert_equal(node["Extension"], Axlsx::RELS_EX.to_s, "relationships content type invalid")
 
     # overrride
     assert_equal(@doc.xpath("//xmlns:Override").size, 4, "There should be 4 Override types")
diff --git a/test/doc_props/tc_app.rb b/test/doc_props/tc_app.rb
index a7124be1..cee3e564 100644
--- a/test/doc_props/tc_app.rb
+++ b/test/doc_props/tc_app.rb
@@ -3,29 +3,29 @@ require 'tc_helper.rb'
 class TestApp < Test::Unit::TestCase
   def setup
     options = {
-      :'Template' => 'Foo.xlt',
-      :'Manager' => 'Penny',
-      :'Company' => "Bob's Repair",
-      :'Pages' => 1,
-      :'Words' => 2,
-      :'Characters' => 7,
-      :'PresentationFormat' => 'any',
-      :'Lines' => 1,
-      :'Paragraphs' => 1,
-      :'Slides' => 4,
-      :'Notes' => 1,
-      :'TotalTime' => 2,
-      :'HidddenSlides' => 3,
-      :'MMClips' => 10,
-      :'ScaleCrop' => true,
-      :'LinksUpToDate' => true,
-      :'CharactersWithSpaces' => 9,
-      :'SharedDoc' => false,
-      :'HyperlinkBase' => 'foo',
-      :'HyperlInksChanged' => false,
-      :'Application' => 'axlsx',
-      :'AppVersion' => '1.1.5',
-      :'DocSecurity' => 0
+      :Template => 'Foo.xlt',
+      :Manager => 'Penny',
+      :Company => "Bob's Repair",
+      :Pages => 1,
+      :Words => 2,
+      :Characters => 7,
+      :PresentationFormat => 'any',
+      :Lines => 1,
+      :Paragraphs => 1,
+      :Slides => 4,
+      :Notes => 1,
+      :TotalTime => 2,
+      :HidddenSlides => 3,
+      :MMClips => 10,
+      :ScaleCrop => true,
+      :LinksUpToDate => true,
+      :CharactersWithSpaces => 9,
+      :SharedDoc => false,
+      :HyperlinkBase => 'foo',
+      :HyperlInksChanged => false,
+      :Application => 'axlsx',
+      :AppVersion => '1.1.5',
+      :DocSecurity => 0
     }
 
     @app = Axlsx::App.new options
@@ -38,6 +38,6 @@ class TestApp < Test::Unit::TestCase
     schema.validate(doc).each do |error|
       errors << error
     end
-    assert_equal(errors.size, 0, "app.xml invalid" + errors.map { |e| e.message }.to_s)
+    assert_equal(errors.size, 0, "app.xml invalid" + errors.map(&:message).to_s)
   end
 end
diff --git a/test/doc_props/tc_core.rb b/test/doc_props/tc_core.rb
index b225266a..d5412a4f 100644
--- a/test/doc_props/tc_core.rb
+++ b/test/doc_props/tc_core.rb
@@ -15,7 +15,7 @@ class TestCore < Test::Unit::TestCase
       puts error.message
       errors << error
     end
-    assert_equal(errors.size, 0, "core.xml Invalid" + errors.map { |e| e.message }.to_s)
+    assert_equal(errors.size, 0, "core.xml Invalid" + errors.map(&:message).to_s)
   end
 
   def test_populates_created
@@ -23,7 +23,7 @@ class TestCore < Test::Unit::TestCase
   end
 
   def test_created_as_option
-    time = Time.utc(2013, 1, 1, 12, 00)
+    time = Time.utc(2013, 1, 1, 12, 0)
     c = Axlsx::Core.new :created => time
     doc = Nokogiri::XML(c.to_xml_string)
     assert_equal(doc.xpath('//dcterms:created').text, time.xmlschema, "dcterms:created incorrect")
diff --git a/test/drawing/tc_area_chart.rb b/test/drawing/tc_area_chart.rb
index fc928db9..490df25a 100644
--- a/test/drawing/tc_area_chart.rb
+++ b/test/drawing/tc_area_chart.rb
@@ -8,8 +8,7 @@ class TestAreaChart < Test::Unit::TestCase
     @chart = ws.add_chart Axlsx::AreaChart, :title => "fishery"
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert_equal(@chart.grouping, :standard, "grouping defualt incorrect")
diff --git a/test/drawing/tc_axis.rb b/test/drawing/tc_axis.rb
index 0f7108eb..0b3bddc0 100644
--- a/test/drawing/tc_axis.rb
+++ b/test/drawing/tc_axis.rb
@@ -103,9 +103,9 @@ class TestAxis < Test::Unit::TestCase
     str << '<c:chartSpace xmlns:c="' << Axlsx::XML_NS_C << '" xmlns:a="' << Axlsx::XML_NS_A << '">'
     doc = Nokogiri::XML(@axis.to_xml_string(str))
     assert(doc.xpath('//a:noFill'))
-    assert(doc.xpath("//c:crosses[@val='#{@axis.crosses.to_s}']"))
-    assert(doc.xpath("//c:crossAx[@val='#{@axis.cross_axis.to_s}']"))
-    assert(doc.xpath("//a:bodyPr[@rot='#{@axis.label_rotation.to_s}']"))
+    assert(doc.xpath("//c:crosses[@val='#{@axis.crosses}']"))
+    assert(doc.xpath("//c:crossAx[@val='#{@axis.cross_axis}']"))
+    assert(doc.xpath("//a:bodyPr[@rot='#{@axis.label_rotation}']"))
     assert(doc.xpath("//a:t[text()='Foo']"))
   end
 end
diff --git a/test/drawing/tc_bar_3D_chart.rb b/test/drawing/tc_bar_3D_chart.rb
index 3c22e191..178ee65a 100644
--- a/test/drawing/tc_bar_3D_chart.rb
+++ b/test/drawing/tc_bar_3D_chart.rb
@@ -8,8 +8,7 @@ class TestBar3DChart < Test::Unit::TestCase
     @chart = ws.add_chart Axlsx::Bar3DChart, :title => "fishery"
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert_equal(@chart.grouping, :clustered, "grouping defualt incorrect")
diff --git a/test/drawing/tc_bar_chart.rb b/test/drawing/tc_bar_chart.rb
index 5106d266..62927bc7 100644
--- a/test/drawing/tc_bar_chart.rb
+++ b/test/drawing/tc_bar_chart.rb
@@ -8,8 +8,7 @@ class TestBarChart < Test::Unit::TestCase
     @chart = ws.add_chart Axlsx::BarChart, :title => "fishery"
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert_equal(@chart.grouping, :clustered, "grouping defualt incorrect")
diff --git a/test/drawing/tc_bar_series.rb b/test/drawing/tc_bar_series.rb
index 39d39b96..a1f98f64 100644
--- a/test/drawing/tc_bar_series.rb
+++ b/test/drawing/tc_bar_series.rb
@@ -36,7 +36,7 @@ class TestBarSeries < Test::Unit::TestCase
 
   def test_to_xml_string
     doc = Nokogiri::XML(@chart.to_xml_string)
-    @series.colors.each_with_index do |color, index|
+    @series.colors.each_with_index do |_color, index|
       assert_equal(doc.xpath("//c:dPt/c:idx[@val='#{index}']").size, 1)
       assert_equal(doc.xpath("//c:dPt/c:spPr/a:solidFill/a:srgbClr[@val='#{@series.colors[index]}']").size, 1)
     end
diff --git a/test/drawing/tc_bubble_chart.rb b/test/drawing/tc_bubble_chart.rb
index 02745f92..eb07afee 100644
--- a/test/drawing/tc_bubble_chart.rb
+++ b/test/drawing/tc_bubble_chart.rb
@@ -21,8 +21,7 @@ class TestBubbleChart < Test::Unit::TestCase
     end
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert_equal(@chart.series_type, Axlsx::BubbleSeries, "series type incorrect")
diff --git a/test/drawing/tc_cat_axis.rb b/test/drawing/tc_cat_axis.rb
index 79c0f8db..2cb029cc 100644
--- a/test/drawing/tc_cat_axis.rb
+++ b/test/drawing/tc_cat_axis.rb
@@ -5,8 +5,7 @@ class TestCatAxis < Test::Unit::TestCase
     @axis = Axlsx::CatAxis.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert_equal(@axis.auto, 1, "axis auto default incorrect")
diff --git a/test/drawing/tc_chart.rb b/test/drawing/tc_chart.rb
index 4f60db17..c39bdc11 100644
--- a/test/drawing/tc_chart.rb
+++ b/test/drawing/tc_chart.rb
@@ -10,8 +10,7 @@ class TestChart < Test::Unit::TestCase
     @chart = ws.add_chart Axlsx::Bar3DChart, :title => "fishery", :bg_color => "000000"
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert_equal(@p.workbook.charts.last, @chart, "the chart is in the workbook")
diff --git a/test/drawing/tc_d_lbls.rb b/test/drawing/tc_d_lbls.rb
index a8647f9c..7f4f77e5 100644
--- a/test/drawing/tc_d_lbls.rb
+++ b/test/drawing/tc_d_lbls.rb
@@ -20,7 +20,7 @@ class TestDLbls < Test::Unit::TestCase
   end
 
   def test_initialization_with_optoins
-    options_hash = Hash[*[@boolean_attributes.map { |name| [name, true] }]]
+    options_hash = @boolean_attributes.map { |name| [name, true] }.to_h
 
     d_lbls = Axlsx::DLbls.new(Axlsx::Pie3DChart, options_hash.merge({ :d_lbl_pos => :t }))
 
diff --git a/test/drawing/tc_graphic_frame.rb b/test/drawing/tc_graphic_frame.rb
index eb638489..c57c4d96 100644
--- a/test/drawing/tc_graphic_frame.rb
+++ b/test/drawing/tc_graphic_frame.rb
@@ -8,8 +8,7 @@ class TestGraphicFrame < Test::Unit::TestCase
     @frame = @chart.graphic_frame
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert(@frame.anchor.is_a?(Axlsx::TwoCellAnchor))
diff --git a/test/drawing/tc_hyperlink.rb b/test/drawing/tc_hyperlink.rb
index f9deb5b8..dd27d084 100644
--- a/test/drawing/tc_hyperlink.rb
+++ b/test/drawing/tc_hyperlink.rb
@@ -9,8 +9,7 @@ class TestHyperlink < Test::Unit::TestCase
     @hyperlink = @image.hyperlink
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_href
     assert_nothing_raised { @hyperlink.href = "http://axlsx.blogspot.com" }
diff --git a/test/drawing/tc_line_3d_chart.rb b/test/drawing/tc_line_3d_chart.rb
index c91e9216..64603b11 100644
--- a/test/drawing/tc_line_3d_chart.rb
+++ b/test/drawing/tc_line_3d_chart.rb
@@ -8,8 +8,7 @@ class TestLine3DChart < Test::Unit::TestCase
     @chart = ws.add_chart Axlsx::Line3DChart, :title => "fishery"
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert_equal(@chart.grouping, :standard, "grouping defualt incorrect")
diff --git a/test/drawing/tc_line_chart.rb b/test/drawing/tc_line_chart.rb
index 113ef844..4a96af44 100644
--- a/test/drawing/tc_line_chart.rb
+++ b/test/drawing/tc_line_chart.rb
@@ -8,8 +8,7 @@ class TestLineChart < Test::Unit::TestCase
     @chart = ws.add_chart Axlsx::LineChart, :title => "fishery"
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert_equal(@chart.grouping, :standard, "grouping defualt incorrect")
diff --git a/test/drawing/tc_marker.rb b/test/drawing/tc_marker.rb
index ccfb76fe..bc801965 100644
--- a/test/drawing/tc_marker.rb
+++ b/test/drawing/tc_marker.rb
@@ -5,8 +5,7 @@ class TestMarker < Test::Unit::TestCase
     @marker = Axlsx::Marker.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert(@marker.col == 0)
diff --git a/test/drawing/tc_num_data.rb b/test/drawing/tc_num_data.rb
index 7e7e12e3..10e35785 100644
--- a/test/drawing/tc_num_data.rb
+++ b/test/drawing/tc_num_data.rb
@@ -9,8 +9,7 @@ class TestNumData < Test::Unit::TestCase
     assert_equal(@num_data.format_code, "General")
   end
 
-  def test_formula_based_cell
-  end
+  def test_formula_based_cell; end
 
   def test_format_code
     assert_raise(ArgumentError) { @num_data.format_code = 7 }
diff --git a/test/drawing/tc_one_cell_anchor.rb b/test/drawing/tc_one_cell_anchor.rb
index 1b18f12e..e0f9da43 100644
--- a/test/drawing/tc_one_cell_anchor.rb
+++ b/test/drawing/tc_one_cell_anchor.rb
@@ -9,8 +9,7 @@ class TestOneCellAnchor < Test::Unit::TestCase
     @anchor = @image.anchor
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert(@anchor.from.col == 0)
diff --git a/test/drawing/tc_picture_locking.rb b/test/drawing/tc_picture_locking.rb
index 6e5de47b..2543b1ca 100644
--- a/test/drawing/tc_picture_locking.rb
+++ b/test/drawing/tc_picture_locking.rb
@@ -5,8 +5,7 @@ class TestPictureLocking < Test::Unit::TestCase
     @item = Axlsx::PictureLocking.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(Axlsx.instance_values_for(@item).size, 1)
diff --git a/test/drawing/tc_pie_3D_chart.rb b/test/drawing/tc_pie_3D_chart.rb
index f536f086..9692ccc4 100644
--- a/test/drawing/tc_pie_3D_chart.rb
+++ b/test/drawing/tc_pie_3D_chart.rb
@@ -8,8 +8,7 @@ class TestPie3DChart < Test::Unit::TestCase
     @chart = ws.add_chart Axlsx::Pie3DChart, :title => "fishery"
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert_equal(@chart.view_3D.rot_x, 30, "view 3d default rot_x incorrect")
diff --git a/test/drawing/tc_pie_series.rb b/test/drawing/tc_pie_series.rb
index c3f5bb3a..2c897fd2 100644
--- a/test/drawing/tc_pie_series.rb
+++ b/test/drawing/tc_pie_series.rb
@@ -27,5 +27,5 @@ class TestPieSeries < Test::Unit::TestCase
     doc = Nokogiri::XML(@series.to_xml_string)
     assert(doc.xpath("//srgbClr[@val='#{@series.colors[0]}']"))
   end
-  # TODO test unique serialization parts
+  # TODO: test unique serialization parts
 end
diff --git a/test/drawing/tc_scaling.rb b/test/drawing/tc_scaling.rb
index 8f92a024..1cd1538b 100644
--- a/test/drawing/tc_scaling.rb
+++ b/test/drawing/tc_scaling.rb
@@ -5,8 +5,7 @@ class TestScaling < Test::Unit::TestCase
     @scaling = Axlsx::Scaling.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert(@scaling.orientation == :minMax)
diff --git a/test/drawing/tc_scatter_chart.rb b/test/drawing/tc_scatter_chart.rb
index 359f7206..42d4a773 100644
--- a/test/drawing/tc_scatter_chart.rb
+++ b/test/drawing/tc_scatter_chart.rb
@@ -19,8 +19,7 @@ class TestScatterChart < Test::Unit::TestCase
     end
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_scatter_style
     @chart.scatterStyle = :marker
diff --git a/test/drawing/tc_ser_axis.rb b/test/drawing/tc_ser_axis.rb
index 4b498a12..80800fb5 100644
--- a/test/drawing/tc_ser_axis.rb
+++ b/test/drawing/tc_ser_axis.rb
@@ -5,8 +5,7 @@ class TestSerAxis < Test::Unit::TestCase
     @axis = Axlsx::SerAxis.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_options
     a = Axlsx::SerAxis.new(:tick_lbl_skip => 9, :tick_mark_skip => 7)
diff --git a/test/drawing/tc_series_title.rb b/test/drawing/tc_series_title.rb
index b85aece3..a304802b 100644
--- a/test/drawing/tc_series_title.rb
+++ b/test/drawing/tc_series_title.rb
@@ -9,19 +9,18 @@ class TestSeriesTitle < Test::Unit::TestCase
     @chart = ws.add_chart Axlsx::Bar3DChart
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert(@title.text == "")
-    assert(@title.cell == nil)
+    assert(@title.cell.nil?)
   end
 
   def test_text
     assert_raise(ArgumentError, "text must be a string") { @title.text = 123 }
     @title.cell = @row.cells.first
     @title.text = "bob"
-    assert(@title.cell == nil, "setting title with text clears the cell")
+    assert(@title.cell.nil?, "setting title with text clears the cell")
   end
 
   def test_cell
diff --git a/test/drawing/tc_title.rb b/test/drawing/tc_title.rb
index eb549b35..f26c307e 100644
--- a/test/drawing/tc_title.rb
+++ b/test/drawing/tc_title.rb
@@ -11,12 +11,11 @@ class TestTitle < Test::Unit::TestCase
     @chart = ws.add_chart Axlsx::Bar3DChart
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert(@title.text == "")
-    assert(@title.cell == nil)
+    assert(@title.cell.nil?)
   end
 
   def test_initialize_title_size
@@ -28,7 +27,7 @@ class TestTitle < Test::Unit::TestCase
     assert_raise(ArgumentError, "text must be a string") { @title.text = 123 }
     @title.cell = @row.cells.first
     @title.text = "bob"
-    assert(@title.cell == nil, "setting title with text clears the cell")
+    assert(@title.cell.nil?, "setting title with text clears the cell")
   end
 
   def test_cell
diff --git a/test/drawing/tc_val_axis.rb b/test/drawing/tc_val_axis.rb
index a607ddb1..cc67f448 100644
--- a/test/drawing/tc_val_axis.rb
+++ b/test/drawing/tc_val_axis.rb
@@ -5,8 +5,7 @@ class TestValAxis < Test::Unit::TestCase
     @axis = Axlsx::ValAxis.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialization
     assert_equal(@axis.cross_between, :between, "axis crossBetween default incorrect")
diff --git a/test/drawing/tc_view_3D.rb b/test/drawing/tc_view_3D.rb
index 43116023..6d59c219 100644
--- a/test/drawing/tc_view_3D.rb
+++ b/test/drawing/tc_view_3D.rb
@@ -5,8 +5,7 @@ class TestView3D < Test::Unit::TestCase
     @view = Axlsx::View3D.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_options
     v = Axlsx::View3D.new :rot_x => 10, :rot_y => 5, :h_percent => "30%", :depth_percent => "45%", :r_ang_ax => false, :perspective => 10
diff --git a/test/drawing/tc_vml_drawing.rb b/test/drawing/tc_vml_drawing.rb
index debba561..1e2132af 100644
--- a/test/drawing/tc_vml_drawing.rb
+++ b/test/drawing/tc_vml_drawing.rb
@@ -15,7 +15,7 @@ class TestVmlDrawing < Test::Unit::TestCase
   end
 
   def test_to_xml_string
-    str = @vml_drawing.to_xml_string()
+    str = @vml_drawing.to_xml_string
     doc = Nokogiri::XML(str)
     assert_equal(doc.xpath("//v:shape").size, 2)
     assert(doc.xpath("//o:idmap[@o:data='#{@ws.index + 1}']"))
diff --git a/test/drawing/tc_vml_shape.rb b/test/drawing/tc_vml_shape.rb
index b8344a92..f93ea48d 100644
--- a/test/drawing/tc_vml_shape.rb
+++ b/test/drawing/tc_vml_shape.rb
@@ -92,7 +92,7 @@ class TestVmlShape < Test::Unit::TestCase
   end
 
   def test_to_xml_string
-    str = @comments.vml_drawing.to_xml_string()
+    str = @comments.vml_drawing.to_xml_string
     doc = Nokogiri::XML(str)
     assert_equal(doc.xpath("//v:shape").size, 2)
     assert_equal(1, doc.xpath("//x:Visible").size, 'ClientData/x:Visible element rendering')
diff --git a/test/profile.rb b/test/profile.rb
index ef42c2f8..a81c813b 100644..100755
--- a/test/profile.rb
+++ b/test/profile.rb
@@ -1,6 +1,6 @@
 #!/usr/bin/env ruby -s
 
-$:.unshift "#{File.dirname(__FILE__)}/../lib"
+$LOAD_PATH.unshift "#{File.dirname(__FILE__)}/../lib"
 require 'axlsx'
 require 'ruby-prof'
 # RubyProf.measure_mode = RubyProf::MEMORY
@@ -21,4 +21,4 @@ profile = RubyProf.profile do
 end
 
 printer = RubyProf::FlatPrinter.new(profile)
-printer.print(STDOUT, {})
+printer.print($stdout, {})
diff --git a/test/rels/tc_relationships.rb b/test/rels/tc_relationships.rb
index 43e413cd..35adbc9b 100644
--- a/test/rels/tc_relationships.rb
+++ b/test/rels/tc_relationships.rb
@@ -2,7 +2,8 @@ require 'tc_helper.rb'
 
 class TestRelationships < Test::Unit::TestCase
   def test_for
-    source_obj_1, source_obj_2 = Object.new, Object.new
+    source_obj_1 = Object.new
+    source_obj_2 = Object.new
     rel_1 = Axlsx::Relationship.new(source_obj_1, Axlsx::WORKSHEET_R, "bar")
     rel_2 = Axlsx::Relationship.new(source_obj_2, Axlsx::WORKSHEET_R, "bar")
     rels = Axlsx::Relationships.new
@@ -30,6 +31,6 @@ class TestRelationships < Test::Unit::TestCase
       errors << error
     end
 
-    assert(errors.size == 0)
+    assert(errors.empty?)
   end
 end
diff --git a/test/stylesheet/tc_border.rb b/test/stylesheet/tc_border.rb
index 9e29dda4..f7791d94 100644
--- a/test/stylesheet/tc_border.rb
+++ b/test/stylesheet/tc_border.rb
@@ -5,8 +5,7 @@ class TestBorder < Test::Unit::TestCase
     @b = Axlsx::Border.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@b.diagonalUp, nil)
diff --git a/test/stylesheet/tc_border_pr.rb b/test/stylesheet/tc_border_pr.rb
index 3b25575b..652f4f6d 100644
--- a/test/stylesheet/tc_border_pr.rb
+++ b/test/stylesheet/tc_border_pr.rb
@@ -5,8 +5,7 @@ class TestBorderPr < Test::Unit::TestCase
     @bpr = Axlsx::BorderPr.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@bpr.color, nil)
diff --git a/test/stylesheet/tc_cell_protection.rb b/test/stylesheet/tc_cell_protection.rb
index a1fc59b2..253b6c82 100644
--- a/test/stylesheet/tc_cell_protection.rb
+++ b/test/stylesheet/tc_cell_protection.rb
@@ -5,8 +5,7 @@ class TestCellProtection < Test::Unit::TestCase
     @item = Axlsx::CellProtection.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.hidden, nil)
diff --git a/test/stylesheet/tc_cell_style.rb b/test/stylesheet/tc_cell_style.rb
index 18e7a1ab..06f20af3 100644
--- a/test/stylesheet/tc_cell_style.rb
+++ b/test/stylesheet/tc_cell_style.rb
@@ -5,8 +5,7 @@ class TestCellStyle < Test::Unit::TestCase
     @item = Axlsx::CellStyle.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.name, nil)
diff --git a/test/stylesheet/tc_color.rb b/test/stylesheet/tc_color.rb
index 8f87111e..46e94f88 100644
--- a/test/stylesheet/tc_color.rb
+++ b/test/stylesheet/tc_color.rb
@@ -5,8 +5,7 @@ class TestColor < Test::Unit::TestCase
     @item = Axlsx::Color.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.auto, nil)
diff --git a/test/stylesheet/tc_dxf.rb b/test/stylesheet/tc_dxf.rb
index 9e87007d..ecbd7112 100644
--- a/test/stylesheet/tc_dxf.rb
+++ b/test/stylesheet/tc_dxf.rb
@@ -6,8 +6,7 @@ class TestDxf < Test::Unit::TestCase
     @styles = Axlsx::Styles.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.alignment, nil)
diff --git a/test/stylesheet/tc_fill.rb b/test/stylesheet/tc_fill.rb
index dd61204f..6e586e45 100644
--- a/test/stylesheet/tc_fill.rb
+++ b/test/stylesheet/tc_fill.rb
@@ -5,8 +5,7 @@ class TestFill < Test::Unit::TestCase
     @item = Axlsx::Fill.new Axlsx::PatternFill.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert(@item.fill_type.is_a?(Axlsx::PatternFill))
diff --git a/test/stylesheet/tc_font.rb b/test/stylesheet/tc_font.rb
index 821e8820..601e7a65 100644
--- a/test/stylesheet/tc_font.rb
+++ b/test/stylesheet/tc_font.rb
@@ -5,8 +5,7 @@ class TestFont < Test::Unit::TestCase
     @item = Axlsx::Font.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.name, nil)
diff --git a/test/stylesheet/tc_gradient_fill.rb b/test/stylesheet/tc_gradient_fill.rb
index 3950fcf7..3707cdad 100644
--- a/test/stylesheet/tc_gradient_fill.rb
+++ b/test/stylesheet/tc_gradient_fill.rb
@@ -5,8 +5,7 @@ class TestGradientFill < Test::Unit::TestCase
     @item = Axlsx::GradientFill.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.type, :linear)
diff --git a/test/stylesheet/tc_gradient_stop.rb b/test/stylesheet/tc_gradient_stop.rb
index 6dc140e0..a4cd4ef8 100644
--- a/test/stylesheet/tc_gradient_stop.rb
+++ b/test/stylesheet/tc_gradient_stop.rb
@@ -5,8 +5,7 @@ class TestGradientStop < Test::Unit::TestCase
     @item = Axlsx::GradientStop.new(Axlsx::Color.new(:rgb => "FFFF0000"), 1.0)
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.color.rgb, "FFFF0000")
diff --git a/test/stylesheet/tc_num_fmt.rb b/test/stylesheet/tc_num_fmt.rb
index 7c34be28..63c818b0 100644
--- a/test/stylesheet/tc_num_fmt.rb
+++ b/test/stylesheet/tc_num_fmt.rb
@@ -5,8 +5,7 @@ class TestNumFmt < Test::Unit::TestCase
     @item = Axlsx::NumFmt.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.numFmtId, 0)
diff --git a/test/stylesheet/tc_pattern_fill.rb b/test/stylesheet/tc_pattern_fill.rb
index 1126e919..228d7ca2 100644
--- a/test/stylesheet/tc_pattern_fill.rb
+++ b/test/stylesheet/tc_pattern_fill.rb
@@ -5,8 +5,7 @@ class TestPatternFill < Test::Unit::TestCase
     @item = Axlsx::PatternFill.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.patternType, :none)
diff --git a/test/stylesheet/tc_styles.rb b/test/stylesheet/tc_styles.rb
index 1598a658..d6e9115a 100644
--- a/test/stylesheet/tc_styles.rb
+++ b/test/stylesheet/tc_styles.rb
@@ -5,8 +5,7 @@ class TestStyles < Test::Unit::TestCase
     @styles = Axlsx::Styles.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_valid_document
     schema = Nokogiri::XML::Schema(File.open(Axlsx::SML_XSD))
@@ -16,7 +15,7 @@ class TestStyles < Test::Unit::TestCase
       errors.push error
       puts error.message
     end
-    assert(errors.size == 0)
+    assert(errors.empty?)
   end
 
   def test_add_style_border_hash
@@ -73,7 +72,7 @@ class TestStyles < Test::Unit::TestCase
     f_code = { :format_code => "YYYY/MM" }
     num_fmt = { :num_fmt => 5 }
     assert_equal(@styles.parse_num_fmt_options, nil, 'noop if neither :format_code or :num_fmt exist')
-    max = @styles.numFmts.map { |nf| nf.numFmtId }.max
+    max = @styles.numFmts.map(&:numFmtId).max
     @styles.parse_num_fmt_options(f_code)
     assert_equal(@styles.numFmts.last.numFmtId, max + 1, "new numfmts gets next available id")
     assert(@styles.parse_num_fmt_options(num_fmt).is_a?(Integer), "Should return the provided num_fmt if not dxf")
@@ -89,7 +88,7 @@ class TestStyles < Test::Unit::TestCase
   def test_parse_border_basic_options
     b_opts = { :border => { :diagonalUp => 1, :edges => [:left, :right], :color => "FFDADADA", :style => :thick } }
     b = @styles.parse_border_options b_opts
-    assert(b.is_a? Integer)
+    assert(b.is_a?(Integer))
     assert_equal(@styles.parse_border_options(b_opts.merge({ :type => :dxf })).class, Axlsx::Border)
     assert(@styles.borders.last.diagonalUp == 1, "border options are passed in to the initializer")
   end
@@ -129,7 +128,7 @@ class TestStyles < Test::Unit::TestCase
   end
 
   def test_parse_alignment_options
-    assert_equal(@styles.parse_alignment_options {}, nil, "noop if :alignment is not set")
+    assert_equal(@styles.parse_alignment_options, nil, "noop if :alignment is not set")
     assert(@styles.parse_alignment_options(:alignment => {}).is_a?(Axlsx::CellAlignment))
   end
 
@@ -140,7 +139,7 @@ class TestStyles < Test::Unit::TestCase
     original_attributes = Axlsx.instance_values_for(original)
     assert_equal(1, created.b)
     assert_equal(99, created.sz)
-    copied = original_attributes.reject { |key, value| %w(b sz).include? key }
+    copied = original_attributes.reject { |key, _value| %w(b sz).include? key }
     instance_vals = Axlsx.instance_values_for(created)
     copied.each do |key, value|
       assert_equal(instance_vals[key], value)
@@ -161,7 +160,7 @@ class TestStyles < Test::Unit::TestCase
       :family => 1,
       :font_name => "woot font"
     }
-    assert_equal(@styles.parse_font_options {}, nil, "noop if no font keys are set")
+    assert_equal(@styles.parse_font_options, nil, "noop if no font keys are set")
     assert(@styles.parse_font_options(:b => 1).is_a?(Integer), "return index of font if not :dxf type")
     assert_equal(@styles.parse_font_options(:b => 1, :type => :dxf).class, Axlsx::Font, "return font object if :dxf type")
 
@@ -175,7 +174,7 @@ class TestStyles < Test::Unit::TestCase
   end
 
   def test_parse_fill_options
-    assert_equal(@styles.parse_fill_options {}, nil, "noop if no fill keys are set")
+    assert_equal(@styles.parse_fill_options, nil, "noop if no fill keys are set")
     assert(@styles.parse_fill_options(:bg_color => "DE").is_a?(Integer), "return index of fill if not :dxf type")
     assert_equal(@styles.parse_fill_options(:bg_color => "DE", :type => :dxf).class, Axlsx::Fill, "return fill object if :dxf type")
     f = @styles.parse_fill_options(:bg_color => "DE", :type => :dxf)
@@ -183,7 +182,7 @@ class TestStyles < Test::Unit::TestCase
   end
 
   def test_parse_protection_options
-    assert_equal(@styles.parse_protection_options {}, nil, "noop if no protection keys are set")
+    assert_equal(@styles.parse_protection_options, nil, "noop if no protection keys are set")
     assert_equal(@styles.parse_protection_options(:hidden => 1).class, Axlsx::CellProtection, "creates a new cell protection object")
   end
 
@@ -240,8 +239,8 @@ class TestStyles < Test::Unit::TestCase
     dxf = @styles.dxfs.last
     assert_equal(@styles.dxfs.last.fill.fill_type.bgColor.rgb, "FF000000", "fill created with color")
 
-    assert_equal(font_count, (@styles.fonts.size), "font not created under styles")
-    assert_equal(fill_count, (@styles.fills.size), "fill not created under styles")
+    assert_equal(font_count, @styles.fonts.size, "font not created under styles")
+    assert_equal(fill_count, @styles.fills.size, "fill not created under styles")
 
     assert(dxf.border.is_a?(Axlsx::Border), "border is set")
     assert_equal(nil, dxf.numFmt, "number format is not set")
@@ -284,7 +283,7 @@ class TestStyles < Test::Unit::TestCase
       errors.push error
       puts error.message
     end
-    assert(errors.size == 0)
+    assert(errors.empty?)
   end
 
   def test_border_top_without_border_regression
diff --git a/test/stylesheet/tc_table_style.rb b/test/stylesheet/tc_table_style.rb
index f86cc54c..a003c37a 100644
--- a/test/stylesheet/tc_table_style.rb
+++ b/test/stylesheet/tc_table_style.rb
@@ -5,8 +5,7 @@ class TestTableStyle < Test::Unit::TestCase
     @item = Axlsx::TableStyle.new "fisher"
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.name, "fisher")
diff --git a/test/stylesheet/tc_table_style_element.rb b/test/stylesheet/tc_table_style_element.rb
index 021d4fca..2b52a23d 100644
--- a/test/stylesheet/tc_table_style_element.rb
+++ b/test/stylesheet/tc_table_style_element.rb
@@ -5,8 +5,7 @@ class TestTableStyleElement < Test::Unit::TestCase
     @item = Axlsx::TableStyleElement.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.type, nil)
@@ -39,6 +38,6 @@ class TestTableStyleElement < Test::Unit::TestCase
   def test_to_xml_string
     doc = Nokogiri::XML(@item.to_xml_string)
     @item.type = :headerRow
-    assert(doc.xpath("//tableStyleElement[@type='#{@item.type.to_s}']"))
+    assert(doc.xpath("//tableStyleElement[@type='#{@item.type}']"))
   end
 end
diff --git a/test/stylesheet/tc_table_styles.rb b/test/stylesheet/tc_table_styles.rb
index 751874b1..5ce315d5 100644
--- a/test/stylesheet/tc_table_styles.rb
+++ b/test/stylesheet/tc_table_styles.rb
@@ -5,8 +5,7 @@ class TestTableStyles < Test::Unit::TestCase
     @item = Axlsx::TableStyles.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.defaultTableStyle, "TableStyleMedium9")
diff --git a/test/stylesheet/tc_xf.rb b/test/stylesheet/tc_xf.rb
index 00e2a8a3..9a972aaf 100644
--- a/test/stylesheet/tc_xf.rb
+++ b/test/stylesheet/tc_xf.rb
@@ -5,8 +5,7 @@ class TestXf < Test::Unit::TestCase
     @item = Axlsx::Xf.new
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_initialiation
     assert_equal(@item.alignment, nil)
diff --git a/test/tc_axlsx.rb b/test/tc_axlsx.rb
index 73fdd9ab..ccfdbfab 100644
--- a/test/tc_axlsx.rb
+++ b/test/tc_axlsx.rb
@@ -3,14 +3,14 @@ require 'tc_helper.rb'
 class TestAxlsx < Test::Unit::TestCase
   def setup_wide
     @wide_test_points = {
-      "A3"    =>                       0,
-      "Z3"    =>                      25,
-      "B3"    =>                       1,
-      "AA3"   =>             1 * 26 +  0,
-      "AAA3"  => 1 * 26**2 + 1 * 26 +  0,
-      "AAZ3"  => 1 * 26**2 + 1 * 26 + 25,
-      "ABA3"  => 1 * 26**2 + 2 * 26 +  0,
-      "BZU3"  => 2 * 26**2 + 26 * 26 + 20
+      "A3"    =>                              0,
+      "Z3"    =>                             25,
+      "B3"    =>                              1,
+      "AA3"   =>                  (1 * 26) +  0,
+      "AAA3"  => (1 * (26**2)) +  (1 * 26) +  0,
+      "AAZ3"  => (1 * (26**2)) +  (1 * 26) + 25,
+      "ABA3"  => (1 * (26**2)) +  (2 * 26) +  0,
+      "BZU3"  => (2 * (26**2)) + (26 * 26) + 20
     }
   end
 
diff --git a/test/tc_package.rb b/test/tc_package.rb
index cc40a6e0..58fe8e76 100644
--- a/test/tc_package.rb
+++ b/test/tc_package.rb
@@ -67,7 +67,7 @@ class TestPackage < Test::Unit::TestCase
     end
 
     @fname = 'axlsx_test_serialization.xlsx'
-    img = File.expand_path('../fixtures/image1.jpeg', __FILE__)
+    img = File.expand_path('fixtures/image1.jpeg', __dir__)
     ws.add_image(:image_src => img, :noSelect => true, :noMove => true, :hyperlink => "http://axlsx.blogspot.com") do |image|
       image.width = 720
       image.height = 666
@@ -75,12 +75,12 @@ class TestPackage < Test::Unit::TestCase
       image.start_at 5, 5
       image.end_at 10, 10
     end
-    ws.add_image :image_src => File.expand_path('../fixtures/image1.gif', __FILE__) do |image|
+    ws.add_image :image_src => File.expand_path('fixtures/image1.gif', __dir__) do |image|
       image.start_at 0, 20
       image.width = 360
       image.height = 333
     end
-    ws.add_image :image_src => File.expand_path('../fixtures/image1.png', __FILE__) do |image|
+    ws.add_image :image_src => File.expand_path('fixtures/image1.png', __dir__) do |image|
       image.start_at 9, 20
       image.width = 180
       image.height = 167
@@ -118,7 +118,7 @@ class TestPackage < Test::Unit::TestCase
     assert(Axlsx.instance_values_for(@package)["app"].is_a?(Axlsx::App), 'App object not created')
     assert(Axlsx.instance_values_for(@package)["core"].is_a?(Axlsx::Core), 'Core object not created')
     assert(@package.workbook.is_a?(Axlsx::Workbook), 'Workbook object not created')
-    assert(Axlsx::Package.new.workbook.worksheets.size == 0, 'Workbook should not have sheets by default')
+    assert(Axlsx::Package.new.workbook.worksheets.empty?, 'Workbook should not have sheets by default')
   end
 
   def test_created_at_is_propagated_to_core
@@ -244,28 +244,28 @@ class TestPackage < Test::Unit::TestCase
   def test_validation
     assert_equal(@package.validate.size, 0, @package.validate)
     Axlsx::Workbook.send(:class_variable_set, :@@date1904, 9900)
-    assert(@package.validate.size > 0)
+    assert([email protected]?)
   end
 
   def test_parts
     p = @package.send(:parts)
     # all parts have an entry
-    assert_equal(p.select { |part| part[:entry] =~ /_rels\/\.rels/ }.size, 1, "rels missing")
-    assert_equal(p.select { |part| part[:entry] =~ /docProps\/core\.xml/ }.size, 1, "core missing")
-    assert_equal(p.select { |part| part[:entry] =~ /docProps\/app\.xml/ }.size, 1, "app missing")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/_rels\/workbook\.xml\.rels/ }.size, 1, "workbook rels missing")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/workbook\.xml/ }.size, 1, "workbook missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{_rels/\.rels} }.size, 1, "rels missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{docProps/core\.xml} }.size, 1, "core missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{docProps/app\.xml} }.size, 1, "app missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/_rels/workbook\.xml\.rels} }.size, 1, "workbook rels missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/workbook\.xml} }.size, 1, "workbook missing")
     assert_equal(p.select { |part| part[:entry] =~ /\[Content_Types\]\.xml/ }.size, 1, "content types missing")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/styles\.xml/ }.size, 1, "styles missin")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/drawings\/_rels\/drawing\d\.xml\.rels/ }.size, @package.workbook.drawings.size, "one or more drawing rels missing")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/drawings\/drawing\d\.xml/ }.size, @package.workbook.drawings.size, "one or more drawings missing")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/charts\/chart\d\.xml/ }.size, @package.workbook.charts.size, "one or more charts missing")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/worksheets\/sheet\d\.xml/ }.size, @package.workbook.worksheets.size, "one or more sheet missing")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/worksheets\/_rels\/sheet\d\.xml\.rels/ }.size, @package.workbook.worksheets.size, "one or more sheet rels missing")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/comments\d\.xml/ }.size, @package.workbook.worksheets.size, "one or more sheet rels missing")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/pivotTables\/pivotTable\d\.xml/ }.size, @package.workbook.worksheets.first.pivot_tables.size, "one or more pivot tables missing")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/pivotTables\/_rels\/pivotTable\d\.xml.rels/ }.size, @package.workbook.worksheets.first.pivot_tables.size, "one or more pivot tables rels missing")
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/pivotCache\/pivotCacheDefinition\d\.xml/ }.size, @package.workbook.worksheets.first.pivot_tables.size, "one or more pivot tables missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/styles\.xml} }.size, 1, "styles missin")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/drawings/_rels/drawing\d\.xml\.rels} }.size, @package.workbook.drawings.size, "one or more drawing rels missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/drawings/drawing\d\.xml} }.size, @package.workbook.drawings.size, "one or more drawings missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/charts/chart\d\.xml} }.size, @package.workbook.charts.size, "one or more charts missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/worksheets/sheet\d\.xml} }.size, @package.workbook.worksheets.size, "one or more sheet missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/worksheets/_rels/sheet\d\.xml\.rels} }.size, @package.workbook.worksheets.size, "one or more sheet rels missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/comments\d\.xml} }.size, @package.workbook.worksheets.size, "one or more sheet rels missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/pivotTables/pivotTable\d\.xml} }.size, @package.workbook.worksheets.first.pivot_tables.size, "one or more pivot tables missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/pivotTables/_rels/pivotTable\d\.xml.rels} }.size, @package.workbook.worksheets.first.pivot_tables.size, "one or more pivot tables rels missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/pivotCache/pivotCacheDefinition\d\.xml} }.size, @package.workbook.worksheets.first.pivot_tables.size, "one or more pivot tables missing")
 
     # no mystery parts
     assert_equal(25, p.size)
@@ -273,14 +273,14 @@ class TestPackage < Test::Unit::TestCase
     # sorted for correct MIME detection
     assert_equal("[Content_Types].xml", p[0][:entry], "first entry should be `[Content_Types].xml`")
     assert_equal("_rels/.rels", p[1][:entry], "second entry should be `_rels/.rels`")
-    assert_match(/\Axl\//, p[2][:entry], "third entry should begin with `xl/`")
+    assert_match(%r{\Axl/}, p[2][:entry], "third entry should begin with `xl/`")
   end
 
   def test_shared_strings_requires_part
     @package.use_shared_strings = true
     @package.to_stream # ensure all cell_serializer paths are hit
     p = @package.send(:parts)
-    assert_equal(p.select { |part| part[:entry] =~ /xl\/sharedStrings.xml/ }.size, 1, "shared strings table missing")
+    assert_equal(p.select { |part| part[:entry] =~ %r{xl/sharedStrings.xml} }.size, 1, "shared strings table missing")
   end
 
   def test_workbook_is_a_workbook
diff --git a/test/util/tc_mime_type_utils.rb b/test/util/tc_mime_type_utils.rb
index 52c49e2e..e469f31e 100644
--- a/test/util/tc_mime_type_utils.rb
+++ b/test/util/tc_mime_type_utils.rb
@@ -8,8 +8,7 @@ class TestMimeTypeUtils < Test::Unit::TestCase
     @test_img_url = "https://example.com/sample-image.png"
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_mime_type_utils
     assert_equal(Axlsx::MimeTypeUtils::get_mime_type(@test_img), 'image/jpeg')
diff --git a/test/util/tc_simple_typed_list.rb b/test/util/tc_simple_typed_list.rb
index fc1ab0a2..5624b903 100644
--- a/test/util/tc_simple_typed_list.rb
+++ b/test/util/tc_simple_typed_list.rb
@@ -4,8 +4,7 @@ class TestSimpleTypedList < Test::Unit::TestCase
     @list = Axlsx::SimpleTypedList.new Integer
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_type_is_a_class_or_array_of_class
     assert_nothing_raised { Axlsx::SimpleTypedList.new Integer }
@@ -29,7 +28,7 @@ class TestSimpleTypedList < Test::Unit::TestCase
   end
 
   def test_concat_should_return_index
-    assert(@list.size == 0)
+    assert(@list.empty?)
     assert(@list << 1 == 0)
     assert(@list << 2 == 1)
     @list.delete_at 0
diff --git a/test/util/tc_validators.rb b/test/util/tc_validators.rb
index 7df2e41b..58aa6b7c 100644
--- a/test/util/tc_validators.rb
+++ b/test/util/tc_validators.rb
@@ -1,10 +1,8 @@
 require 'tc_helper.rb'
 class TestValidators < Test::Unit::TestCase
-  def setup
-  end
+  def setup; end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_validators
     # unsigned_int
@@ -20,7 +18,7 @@ class TestValidators < Test::Unit::TestCase
     assert_raise(ArgumentError) { Axlsx.validate_int(Array) }
 
     # boolean (as 0 or 1, :true, :false, true, false, or "true," "false")
-    [0, 1, :true, :false, true, false, "true", "false"].each do |v|
+    [0, 1, :true, :false, true, false, "true", "false"].each do |_v|
       assert_nothing_raised { Axlsx.validate_boolean 0 }
     end
     assert_raise(ArgumentError) { Axlsx.validate_boolean 2 }
diff --git a/test/workbook/tc_shared_strings_table.rb b/test/workbook/tc_shared_strings_table.rb
index cb7557c6..775f6ae7 100644
--- a/test/workbook/tc_shared_strings_table.rb
+++ b/test/workbook/tc_shared_strings_table.rb
@@ -39,7 +39,7 @@ class TestSharedStringsTable < Test::Unit::TestCase
       puts error.message
       errors << error
     end
-    assert_equal(errors.size, 0, "sharedStirngs.xml Invalid" + errors.map { |e| e.message }.to_s)
+    assert_equal(errors.size, 0, "sharedStirngs.xml Invalid" + errors.map(&:message).to_s)
   end
 
   def test_remove_control_characters_in_xml_serialization
@@ -47,7 +47,7 @@ class TestSharedStringsTable < Test::Unit::TestCase
     @p.workbook.worksheets[0].add_row [nasties]
 
     # test that the nasty string was added to the shared strings
-    assert @p.workbook.shared_strings.unique_cells.has_key?(nasties)
+    assert @p.workbook.shared_strings.unique_cells.key?(nasties)
 
     # test that none of the control characters are in the XML output for shared strings
     assert_no_match(/#{Axlsx::CONTROL_CHARS}/, @p.workbook.shared_strings.to_xml_string)
diff --git a/test/workbook/tc_workbook.rb b/test/workbook/tc_workbook.rb
index 443dd392..f0a7ac19 100644
--- a/test/workbook/tc_workbook.rb
+++ b/test/workbook/tc_workbook.rb
@@ -6,8 +6,7 @@ class TestWorkbook < Test::Unit::TestCase
     @wb = p.workbook
   end
 
-  def teardown
-  end
+  def teardown; end
 
   def test_worksheet_users_xml_space
     sheet = @wb.add_worksheet(:name => 'foo')
diff --git a/test/workbook/worksheet/tc_cell.rb b/test/workbook/worksheet/tc_cell.rb
index 907ce97e..959304c8 100644
--- a/test/workbook/worksheet/tc_cell.rb
+++ b/test/workbook/worksheet/tc_cell.rb
@@ -99,7 +99,7 @@ class TestCell < Test::Unit::TestCase
     assert_raise(ArgumentError, "type must be :string, :integer, :float, :date, :time, :boolean") { @c.type = :array }
     assert_nothing_raised("type can be changed") { @c.type = :string }
     assert_equal(@c.value, "1.0", "changing type casts the value")
-    assert_equal(:float, @row.add_cell(1.0 / 10**7).type, 'properly identify exponential floats as float type')
+    assert_equal(:float, @row.add_cell(1.0 / (10**7)).type, 'properly identify exponential floats as float type')
     assert_equal(@row.add_cell(Time.now).type, :time, 'time should be time')
     assert_equal(@row.add_cell(Date.today).type, :date, 'date should be date')
     assert_equal(@row.add_cell(true).type, :boolean, 'boolean should be boolean')
@@ -112,7 +112,7 @@ class TestCell < Test::Unit::TestCase
   end
 
   def test_col_ref
-    # TODO move to axlsx spec
+    # TODO: move to axlsx spec
     assert_equal(Axlsx.col_ref(0), "A")
   end
 
@@ -133,7 +133,7 @@ class TestCell < Test::Unit::TestCase
     assert_equal(@c.send(:cell_type_from_value, -1), :integer)
     assert_equal(@c.send(:cell_type_from_value, true), :boolean)
     assert_equal(@c.send(:cell_type_from_value, false), :boolean)
-    assert_equal(@c.send(:cell_type_from_value, 1.0 / 10**6), :float)
+    assert_equal(@c.send(:cell_type_from_value, 1.0 / (10**6)), :float)
     assert_equal(@c.send(:cell_type_from_value, Axlsx::RichText.new), :richtext)
     assert_equal(:iso_8601, @c.send(:cell_type_from_value, '2008-08-30T01:45:36.123+09:00'))
   end
@@ -520,7 +520,7 @@ class TestCell < Test::Unit::TestCase
   end
 
   def test_to_xml
-    # TODO This could use some much more stringent testing related to the xml content generated!
+    # TODO: This could use some much more stringent testing related to the xml content generated!
     @ws.add_row [Time.now, Date.today, true, 1, 1.0, "text", "=sum(A1:A2)", "2013-01-13T13:31:25.123"]
     @ws.rows.last.cells[5].u = true
 
diff --git a/test/workbook/worksheet/tc_col.rb b/test/workbook/worksheet/tc_col.rb
index 908e9931..986c6bb7 100644
--- a/test/workbook/worksheet/tc_col.rb
+++ b/test/workbook/worksheet/tc_col.rb
@@ -86,6 +86,6 @@ class TestCol < Test::Unit::TestCase
     assert_equal(@col.style, nil)
     @col.style = 1
     assert_equal(@col.style, 1)
-    # TODO check that the style specified is actually in the styles xfs collection
+    # TODO: check that the style specified is actually in the styles xfs collection
   end
 end
diff --git a/test/workbook/worksheet/tc_comment.rb b/test/workbook/worksheet/tc_comment.rb
index cbd93f01..8d5df652 100644
--- a/test/workbook/worksheet/tc_comment.rb
+++ b/test/workbook/worksheet/tc_comment.rb
@@ -53,7 +53,7 @@ class TestComment < Test::Unit::TestCase
   def test_to_xml_string
     doc = Nokogiri::XML(@c1.to_xml_string)
     assert_equal(doc.xpath("//comment[@ref='#{@c1.ref}']").size, 1)
-    assert_equal(doc.xpath("//comment[@authorId='#{@c1.author_index.to_s}']").size, 1)
+    assert_equal(doc.xpath("//comment[@authorId='#{@c1.author_index}']").size, 1)
     assert_equal(doc.xpath("//t[text()='#{@c1.author}:\n']").size, 1)
     assert_equal(doc.xpath("//t[text()='#{@c1.text}']").size, 1)
   end
diff --git a/test/workbook/worksheet/tc_comments.rb b/test/workbook/worksheet/tc_comments.rb
index 276dd3b0..cb2e3741 100644
--- a/test/workbook/worksheet/tc_comments.rb
+++ b/test/workbook/worksheet/tc_comments.rb
@@ -16,7 +16,7 @@ class TestComments < Test::Unit::TestCase
 
   def test_add_comment
     assert_equal(@ws.comments.size, 2)
-    assert_raise(ArgumentError) { @ws.comments.add_comment() }
+    assert_raise(ArgumentError) { @ws.comments.add_comment }
     assert_raise(ArgumentError) { @ws.comments.add_comment(:text => 'Yes We Can', :ref => 'A1') }
     assert_raise(ArgumentError) { @ws.comments.add_comment(:author => 'bob', :ref => 'A1') }
     assert_raise(ArgumentError) { @ws.comments.add_comment(:author => 'bob', :text => 'Yes We Can') }
@@ -49,7 +49,7 @@ class TestComments < Test::Unit::TestCase
     end
     assert_equal(0, errors.length)
 
-    # TODO figure out why these xpath expressions dont work!
+    # TODO: figure out why these xpath expressions dont work!
     # assert(doc.xpath("//comments"))
     # assert_equal(doc.xpath("//xmlns:author").size, @ws.comments.authors.size)
     # assert_equal(doc.xpath("//comment").size, @ws.comments.size)
diff --git a/test/workbook/worksheet/tc_data_validation.rb b/test/workbook/worksheet/tc_data_validation.rb
index ff92b847..aac2019d 100644
--- a/test/workbook/worksheet/tc_data_validation.rb
+++ b/test/workbook/worksheet/tc_data_validation.rb
@@ -44,14 +44,14 @@ class TestDataValidation < Test::Unit::TestCase
   end
 
   def test_boolean_attribute_validation
-    @boolean_options.each do |key, value|
+    @boolean_options.each do |key, _value|
       assert_raise(ArgumentError, "#{key} must be boolean") { @dv.send("#{key}=".to_sym, 'A') }
       assert_nothing_raised { @dv.send("#{key}=".to_sym, true) }
     end
   end
 
   def test_string_attribute_validation
-    @string_options.each do |key, value|
+    @string_options.each do |key, _value|
       assert_raise(ArgumentError, "#{key} must be string") { @dv.send("#{key}=".to_sym, :symbol) }
       assert_nothing_raised { @dv.send("#{key}=".to_sym, "foo") }
     end
diff --git a/test/workbook/worksheet/tc_date_time_converter.rb b/test/workbook/worksheet/tc_date_time_converter.rb
index 9c813486..891fa80f 100644
--- a/test/workbook/worksheet/tc_date_time_converter.rb
+++ b/test/workbook/worksheet/tc_date_time_converter.rb
@@ -7,7 +7,7 @@ class TestDateTimeConverter < Test::Unit::TestCase
       Time.parse "1893-08-05"
       Time.parse "9999-12-31T23:59:59Z"
       true
-    rescue
+    rescue StandardError
       false
     end
   end
@@ -114,8 +114,8 @@ class TestDateTimeConverter < Test::Unit::TestCase
     local = Time.parse "2012-01-01 09:00:00 +0900"
 
     assert_equal local, utc
-    assert_equal Axlsx::DateTimeConverter::time_to_serial(local) - local.utc_offset.to_f / 86400, Axlsx::DateTimeConverter::time_to_serial(utc)
+    assert_equal Axlsx::DateTimeConverter::time_to_serial(local) - (local.utc_offset.to_f / 86400), Axlsx::DateTimeConverter::time_to_serial(utc)
     Axlsx::Workbook.date1904 = true
-    assert_equal Axlsx::DateTimeConverter::time_to_serial(local) - local.utc_offset.to_f / 86400, Axlsx::DateTimeConverter::time_to_serial(utc)
+    assert_equal Axlsx::DateTimeConverter::time_to_serial(local) - (local.utc_offset.to_f / 86400), Axlsx::DateTimeConverter::time_to_serial(utc)
   end
 end
diff --git a/test/workbook/worksheet/tc_page_setup.rb b/test/workbook/worksheet/tc_page_setup.rb
index b7a36600..6dca8b0a 100644
--- a/test/workbook/worksheet/tc_page_setup.rb
+++ b/test/workbook/worksheet/tc_page_setup.rb
@@ -59,18 +59,18 @@ class TestPageSetup < Test::Unit::TestCase
   end
 
   def test_default_fit_to_page?
-    assert(@ps.fit_to_width == nil && @ps.fit_to_height == nil)
+    assert(@ps.fit_to_width.nil? && @ps.fit_to_height.nil?)
     assert(@ps.fit_to_page? == false)
   end
 
   def test_with_height_fit_to_page?
-    assert(@ps.fit_to_width == nil && @ps.fit_to_height == nil)
+    assert(@ps.fit_to_width.nil? && @ps.fit_to_height.nil?)
     @ps.set(:fit_to_height => 1)
     assert(@ps.fit_to_page?)
   end
 
   def test_with_width_fit_to_page?
-    assert(@ps.fit_to_width == nil && @ps.fit_to_height == nil)
+    assert(@ps.fit_to_width.nil? && @ps.fit_to_height.nil?)
     @ps.set(:fit_to_width => 1)
     assert(@ps.fit_to_page?)
   end
diff --git a/test/workbook/worksheet/tc_rich_text.rb b/test/workbook/worksheet/tc_rich_text.rb
index 34117b1b..6c9627d4 100644
--- a/test/workbook/worksheet/tc_rich_text.rb
+++ b/test/workbook/worksheet/tc_rich_text.rb
@@ -7,7 +7,7 @@ class RichText < Test::Unit::TestCase
     p.workbook.styles.add_style :sz => 20
     @rt = Axlsx::RichText.new
     b = true
-    (0..26).each do |r|
+    27.times do |r|
       @rt.add_run "run #{r}, ", :b => (b = !b), :i => !b
     end
     @row = @ws.add_row [@rt]
@@ -17,7 +17,7 @@ class RichText < Test::Unit::TestCase
   def test_initialize
     assert_equal(@c.value, @rt)
     rt_direct = Axlsx::RichText.new('hi', :i => true)
-    rt_indirect = Axlsx::RichText.new()
+    rt_indirect = Axlsx::RichText.new
     rt_indirect.add_run('hi', :i => true)
     assert_equal(rt_direct.runs.length, 1)
     assert_equal(rt_indirect.runs.length, 1)
diff --git a/test/workbook/worksheet/tc_sheet_protection.rb b/test/workbook/worksheet/tc_sheet_protection.rb
index b14f3e03..e8f18df5 100644
--- a/test/workbook/worksheet/tc_sheet_protection.rb
+++ b/test/workbook/worksheet/tc_sheet_protection.rb
@@ -44,7 +44,7 @@ class TestSheetProtection < Test::Unit::TestCase
   end
 
   def test_boolean_attribute_validation
-    @boolean_options.each do |key, value|
+    @boolean_options.each do |key, _value|
       assert_raise(ArgumentError, "#{key} must be boolean") { @sp.send("#{key}=".to_sym, 'A') }
       assert_nothing_raised { @sp.send("#{key}=".to_sym, true) }
       assert_nothing_raised { @sp.send("#{key}=".to_sym, true) }
diff --git a/test/workbook/worksheet/tc_sheet_view.rb b/test/workbook/worksheet/tc_sheet_view.rb
index 0f0986cf..18bb3308 100644
--- a/test/workbook/worksheet/tc_sheet_view.rb
+++ b/test/workbook/worksheet/tc_sheet_view.rb
@@ -45,14 +45,14 @@ class TestSheetView < Test::Unit::TestCase
   end
 
   def test_boolean_attribute_validation
-    @boolean_options.each do |key, value|
+    @boolean_options.each do |key, _value|
       assert_raise(ArgumentError, "#{key} must be boolean") { @sv.send("#{key}=".to_sym, 'A') }
       assert_nothing_raised { @sv.send("#{key}=".to_sym, true) }
     end
   end
 
   def test_string_attribute_validation
-    @string_options.each do |key, value|
+    @string_options.each do |key, _value|
       assert_raise(ArgumentError, "#{key} must be string") { @sv.send("#{key}=".to_sym, :symbol) }
       assert_nothing_raised { @sv.send("#{key}=".to_sym, "foo") }
     end
diff --git a/test/workbook/worksheet/tc_table_style_info.rb b/test/workbook/worksheet/tc_table_style_info.rb
index 3d71dc9b..f6606225 100644
--- a/test/workbook/worksheet/tc_table_style_info.rb
+++ b/test/workbook/worksheet/tc_table_style_info.rb
@@ -24,7 +24,7 @@ class TestTableStyleInfo < Test::Unit::TestCase
 
   def test_boolean_properties
     table_style = Axlsx::TableStyleInfo.new
-    @options.keys.each do |key|
+    @options.each_key do |key|
       assert_nothing_raised { table_style.send("#{key.to_sym}=", true) }
       assert_raises(ArgumentError) { table_style.send(key.to_sym, 'foo') }
     end
diff --git a/test/workbook/worksheet/tc_worksheet.rb b/test/workbook/worksheet/tc_worksheet.rb
index d83cdf91..fde0611d 100644
--- a/test/workbook/worksheet/tc_worksheet.rb
+++ b/test/workbook/worksheet/tc_worksheet.rb
@@ -45,7 +45,7 @@ class TestWorksheet < Test::Unit::TestCase
   def test_exception_if_name_too_long_because_of_multibyte_characters
     four_characters_for_excel = "\u{1F1EB 1F1F7}" # french flag emoji
     assert_raises(ArgumentError, "name too long!") do
-      @ws.name = four_characters_for_excel + "x" * 28
+      @ws.name = four_characters_for_excel + ("x" * 28)
     end
     assert_nothing_raised { @ws.name = "#{four_characters_for_excel}123456789012345678901234567" }
     assert_nothing_raised { @ws.name = "123456789012345678901234567890…" }
@@ -53,45 +53,45 @@ class TestWorksheet < Test::Unit::TestCase
   end
 
   def test_page_margins
-    assert(@ws.page_margins.is_a? Axlsx::PageMargins)
+    assert(@ws.page_margins.is_a?(Axlsx::PageMargins))
   end
 
   def test_page_margins_yeild
     @ws.page_margins do |pm|
-      assert(pm.is_a? Axlsx::PageMargins)
+      assert(pm.is_a?(Axlsx::PageMargins))
       assert(@ws.page_margins == pm)
     end
   end
 
   def test_page_setup
-    assert(@ws.page_setup.is_a? Axlsx::PageSetup)
+    assert(@ws.page_setup.is_a?(Axlsx::PageSetup))
   end
 
   def test_page_setup_yield
     @ws.page_setup do |ps|
-      assert(ps.is_a? Axlsx::PageSetup)
+      assert(ps.is_a?(Axlsx::PageSetup))
       assert(@ws.page_setup == ps)
     end
   end
 
   def test_print_options
-    assert(@ws.print_options.is_a? Axlsx::PrintOptions)
+    assert(@ws.print_options.is_a?(Axlsx::PrintOptions))
   end
 
   def test_print_options_yield
     @ws.print_options do |po|
-      assert(po.is_a? Axlsx::PrintOptions)
+      assert(po.is_a?(Axlsx::PrintOptions))
       assert(@ws.print_options == po)
     end
   end
 
   def test_header_footer
-    assert(@ws.header_footer.is_a? Axlsx::HeaderFooter)
+    assert(@ws.header_footer.is_a?(Axlsx::HeaderFooter))
   end
 
   def test_header_footer_yield
     @ws.header_footer do |hf|
-      assert(hf.is_a? Axlsx::HeaderFooter)
+      assert(hf.is_a?(Axlsx::HeaderFooter))
       assert(@ws.header_footer == hf)
     end
   end
@@ -117,16 +117,16 @@ class TestWorksheet < Test::Unit::TestCase
     print_options = { :grid_lines => true, :headings => true, :horizontal_centered => true, :vertical_centered => true }
     header_footer = { :different_first => false, :different_odd_even => false, :odd_header => 'Header' }
     optioned = @ws.workbook.add_worksheet(:name => 'bob', :page_margins => page_margins, :page_setup => page_setup, :print_options => print_options, :header_footer => header_footer)
-    page_margins.keys.each do |key|
+    page_margins.each_key do |key|
       assert_equal(page_margins[key], optioned.page_margins.send(key))
     end
-    page_setup.keys.each do |key|
+    page_setup.each_key do |key|
       assert_equal(page_setup[key], optioned.page_setup.send(key))
     end
-    print_options.keys.each do |key|
+    print_options.each_key do |key|
       assert_equal(print_options[key], optioned.print_options.send(key))
     end
-    header_footer.keys.each do |key|
+    header_footer.each_key do |key|
       assert_equal(header_footer[key], optioned.header_footer.send(key))
     end
     assert_equal(optioned.name, 'bob')
@@ -215,7 +215,7 @@ class TestWorksheet < Test::Unit::TestCase
   end
 
   def test_drawing
-    assert @ws.drawing == nil
+    assert @ws.drawing.nil?
     @ws.add_chart(Axlsx::Pie3DChart)
     assert @ws.drawing.is_a?(Axlsx::Drawing)
   end
@@ -260,7 +260,7 @@ class TestWorksheet < Test::Unit::TestCase
   def test_cols_with_block
     @ws.add_row [1, 2, 3]
     @ws.add_row [1]
-    cols = @ws.cols { |row, column| :foo }
+    cols = @ws.cols { |_row, _column| :foo }
     assert_equal(:foo, cols[1][1])
   end
 
@@ -451,7 +451,7 @@ class TestWorksheet < Test::Unit::TestCase
     @ws.add_pivot_table 'G5:G6', 'A1:D10'
     schema = Nokogiri::XML::Schema(File.open(Axlsx::SML_XSD))
     doc = Nokogiri::XML(@ws.to_xml_string)
-    assert(schema.validate(doc).map { |e| puts e.message; e }.empty?, schema.validate(doc).map { |e| e.message }.join('\n'))
+    assert(schema.validate(doc).map { |e| puts e.message; e }.empty?, schema.validate(doc).map(&:message).join('\n'))
   end
 
   def test_relationships
@@ -786,7 +786,7 @@ class TestWorksheet < Test::Unit::TestCase
       sz: 11,
       family: 1
     }
-    assert_equal b2_cell_style, wb.styles.style_index.values.find { |x| x == b2_cell_style }
+    assert_equal b2_cell_style, (wb.styles.style_index.values.find { |x| x == b2_cell_style })
 
     d3_cell_style = {
       border: {
@@ -799,7 +799,7 @@ class TestWorksheet < Test::Unit::TestCase
       sz: 11,
       family: 1
     }
-    assert_equal d3_cell_style, wb.styles.style_index.values.find { |x| x == d3_cell_style }
+    assert_equal d3_cell_style, (wb.styles.style_index.values.find { |x| x == d3_cell_style })
   end
 
   def test_mixed_borders_1