1 files changed, 74 insertions, 0 deletions
diff --git a/spec/ruby/core/array/concat_spec.rb b/spec/ruby/core/array/concat_spec.rb
new file mode 100644
index 0000000000..f3cab9c17c
--- /dev/null
+++ b/spec/ruby/core/array/concat_spec.rb
@@ -0,0 +1,74 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Array#concat" do
+  it "returns the array itself" do
+    ary = [1,2,3]
+    ary.concat([4,5,6]).equal?(ary).should be_true
+  end
+
+  it "appends the elements in the other array" do
+    ary = [1, 2, 3]
+    ary.concat([9, 10, 11]).should equal(ary)
+    ary.should == [1, 2, 3, 9, 10, 11]
+    ary.concat([])
+    ary.should == [1, 2, 3, 9, 10, 11]
+  end
+
+  it "does not loop endlessly when argument is self" do
+    ary = ["x", "y"]
+    ary.concat(ary).should == ["x", "y", "x", "y"]
+  end
+
+  it "tries to convert the passed argument to an Array using #to_ary" do
+    obj = mock('to_ary')
+    obj.should_receive(:to_ary).and_return(["x", "y"])
+    [4, 5, 6].concat(obj).should == [4, 5, 6, "x", "y"]
+  end
+
+  it "does not call #to_ary on Array subclasses" do
+    obj = ArraySpecs::ToAryArray[5, 6, 7]
+    obj.should_not_receive(:to_ary)
+    [].concat(obj).should == [5, 6, 7]
+  end
+
+  it "raises a FrozenError when Array is frozen and modification occurs" do
+    -> { ArraySpecs.frozen_array.concat [1] }.should raise_error(FrozenError)
+  end
+
+  # see [ruby-core:23666]
+  it "raises a FrozenError when Array is frozen and no modification occurs" do
+    -> { ArraySpecs.frozen_array.concat([]) }.should raise_error(FrozenError)
+  end
+
+  it "appends elements to an Array with enough capacity that has been shifted" do
+    ary = [1, 2, 3, 4, 5]
+    2.times { ary.shift }
+    2.times { ary.pop }
+    ary.concat([5, 6]).should == [3, 5, 6]
+  end
+
+  it "appends elements to an Array without enough capacity that has been shifted" do
+    ary = [1, 2, 3, 4]
+    3.times { ary.shift }
+    ary.concat([5, 6]).should == [4, 5, 6]
+  end
+
+  it "takes multiple arguments" do
+    ary = [1, 2]
+    ary.concat [3, 4]
+    ary.should == [1, 2, 3, 4]
+  end
+
+  it "concatenates the initial value when given arguments contain 2 self" do
+    ary = [1, 2]
+    ary.concat ary, ary
+    ary.should == [1, 2, 1, 2, 1, 2]
+  end
+
+  it "returns self when given no arguments" do
+    ary = [1, 2]
+    ary.concat.should equal(ary)
+    ary.should == [1, 2]
+  end
+end