Prevent Excel from crashing when multiple data columns are added to PivotTable

Excel will crash unless both `colFields` and `colItems` are declared in the PivotTable xml.

First `field` of `colFields` needs to be set to -2 to tell Excel that the value columns comes from individual columns and not groups.
I do not know why `colItems` are needed, but when set, the Excel document opens without crashing.

1 files changed, 14 insertions, 2 deletions

diff --git a/test/workbook/worksheet/tc_pivot_table.rb b/test/workbook/worksheet/tc_pivot_table.rb
index c7aa53cc..f676a72d 100644
--- a/test/workbook/worksheet/tc_pivot_table.rb
+++ b/test/workbook/worksheet/tc_pivot_table.rb
@@ -162,15 +162,27 @@ class TestPivotTable < Test::Unit::TestCase
       pt.data = [
         {ref: "Gross amount", num_fmt: 2},
         {ref: "Net amount", num_fmt: 2},
+        {ref: "Margin", num_fmt: 2},
       ]
     end
 
     xml = pivot_table.to_xml_string
 
+    assert(!xml.include?('dataOnRows'))
     assert(xml.include?('colFields'))
+    assert(xml.include?('colItems'))
+
+    doc = Nokogiri::XML(pivot_table.to_xml_string)
+
+    assert_equal('1', doc.at_css('colFields')['count'])
+    assert_equal('-2', doc.at_css('colFields field')['x'])
+
+    assert_equal('3', doc.at_css('colItems')['count'])
+    assert_equal( 3, doc.at_css('colItems').children.size)
+    assert_nil( doc.at_css('colItems i')['x'])
+    assert_equal('1', doc.at_css('colItems i[i=1] x')['v'])
+    assert_equal('2', doc.at_css('colItems i[i=2] x')['v'])
 
-    assert(!xml.include?('dataOnRows'))
-    assert(!xml.include?('colItems'))
   end
 
   def test_pivot_table_with_only_one_data_row