1 files changed, 42 insertions, 0 deletions
diff --git a/spec/ruby/core/array/each_index_spec.rb b/spec/ruby/core/array/each_index_spec.rb
new file mode 100644
index 0000000000..8872c00f8c
--- /dev/null
+++ b/spec/ruby/core/array/each_index_spec.rb
@@ -0,0 +1,42 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+require File.expand_path('../shared/enumeratorize', __FILE__)
+require File.expand_path('../../enumerable/shared/enumeratorized', __FILE__)
+
+# Modifying a collection while the contents are being iterated
+# gives undefined behavior. See
+# http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/23633
+
+describe "Array#each_index" do
+  before :each do
+    ScratchPad.record []
+  end
+
+  it "passes the index of each element to the block" do
+    a = ['a', 'b', 'c', 'd']
+    a.each_index { |i| ScratchPad << i }
+    ScratchPad.recorded.should == [0, 1, 2, 3]
+  end
+
+  it "returns self" do
+    a = [:a, :b, :c]
+    a.each_index { |i| }.should equal(a)
+  end
+
+  it "is not confused by removing elements from the front" do
+    a = [1, 2, 3]
+
+    a.shift
+    ScratchPad.record []
+    a.each_index { |i| ScratchPad << i }
+    ScratchPad.recorded.should == [0, 1]
+
+    a.shift
+    ScratchPad.record []
+    a.each_index { |i| ScratchPad << i }
+    ScratchPad.recorded.should == [0]
+  end
+
+  it_behaves_like :enumeratorize, :each_index
+  it_behaves_like :enumeratorized_with_origin_size, :each_index, [1,2,3]
+end