1 files changed, 63 insertions, 0 deletions
diff --git a/test/t/string.rb b/test/t/string.rb
index 7326adce9..87aec0e21 100644
--- a/test/t/string.rb
+++ b/test/t/string.rb
@@ -122,6 +122,69 @@ assert('String#[] with Range') do
   assert_equal 'bc', j2
 end
 
+assert('String#[]=') do
+  # length of args is 1
+  a = 'abc'
+  a[0] = 'X'
+  assert_equal 'Xbc', a
+
+  b = 'abc'
+  b[-1] = 'X'
+  assert_equal 'abX', b
+
+  c = 'abc'
+  assert_raise(IndexError) do
+    c[10] = 'X'
+  end
+
+  d = 'abc'
+  assert_raise(IndexError) do
+    d[-10] = 'X'
+  end
+
+  e = 'abc'
+  e[1.1] = 'X'
+  assert_equal 'aXc', e
+
+
+  # length of args is 2
+  a1 = 'abc'
+  assert_raise(IndexError) do
+    a1[0, -1] = 'X'
+  end
+
+  b1 = 'abc'
+  assert_raise(IndexError) do
+    b1[10, 0] = 'X'
+  end
+
+  c1 = 'abc'
+  assert_raise(IndexError) do
+    c1[-10, 0] = 'X'
+  end
+
+  d1 = 'abc'
+  d1[0, 0] = 'X'
+  assert_equal 'Xabc', d1
+
+  e1 = 'abc'
+  e1[1, 3] = 'X'
+  assert_equal 'aX', e1
+
+  # args is RegExp
+  # It will be tested in mrbgems.
+
+  # args is String
+  a3 = 'abc'
+  a3['bc'] = 'X'
+  assert_equal a3, 'aX'
+
+  b3 = 'abc'
+  assert_raise(IndexError) do
+    b3['XX'] = 'Y'
+  end
+end
+
 assert('String#capitalize', '15.2.10.5.7') do
   a = 'abc'
   a.capitalize