1 files changed, 106 insertions, 0 deletions
diff --git a/spec/ruby/core/hash/to_h_spec.rb b/spec/ruby/core/hash/to_h_spec.rb
new file mode 100644
index 0000000000..5d5a280dac
--- /dev/null
+++ b/spec/ruby/core/hash/to_h_spec.rb
@@ -0,0 +1,106 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Hash#to_h" do
+  it "returns self for Hash instances" do
+    h = {}
+    h.to_h.should.equal?(h)
+  end
+
+  describe "when called on a subclass of Hash" do
+    before :each do
+      @h = HashSpecs::MyHash.new
+      @h[:foo] = :bar
+    end
+
+    it "returns a new Hash instance" do
+      @h.to_h.should.instance_of?(Hash)
+      @h.to_h.should == @h
+      @h[:foo].should == :bar
+    end
+
+    it "retains the default" do
+      @h.default = 42
+      @h.to_h.default.should == 42
+      @h[:hello].should == 42
+    end
+
+    it "retains the default_proc" do
+      @h.default_proc = prc = Proc.new{ |h, k| h[k] = 2 * k }
+      @h.to_h.default_proc.should == prc
+      @h[42].should == 84
+    end
+
+    it "retains compare_by_identity flag" do
+      @h.compare_by_identity
+      @h.to_h.compare_by_identity?.should == true
+    end
+  end
+
+  context "with block" do
+    it "converts [key, value] pairs returned by the block to a hash" do
+      { a: 1, b: 2 }.to_h { |k, v| [k.to_s, v*v]}.should == { "a" => 1, "b" => 4 }
+    end
+
+    it "passes to a block each pair's key and value as separate arguments" do
+      ScratchPad.record []
+      { a: 1, b: 2 }.to_h { |k, v| ScratchPad << [k, v]; [k, v] }
+      ScratchPad.recorded.sort.should == [[:a, 1], [:b, 2]]
+
+      ScratchPad.record []
+      { a: 1, b: 2 }.to_h { |*args| ScratchPad << args; [args[0], args[1]] }
+      ScratchPad.recorded.sort.should == [[:a, 1], [:b, 2]]
+    end
+
+    it "raises ArgumentError if block returns longer or shorter array" do
+      -> do
+        { a: 1, b: 2 }.to_h { |k, v| [k.to_s, v*v, 1] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+
+      -> do
+        { a: 1, b: 2 }.to_h { |k, v| [k] }
+      end.should.raise(ArgumentError, /element has wrong array length/)
+    end
+
+    it "raises TypeError if block returns something other than Array" do
+      -> do
+        { a: 1, b: 2 }.to_h { |k, v| "not-array" }
+      end.should.raise(TypeError, /wrong element type String/)
+    end
+
+    it "coerces returned pair to Array with #to_ary" do
+      x = mock('x')
+      x.stub!(:to_ary).and_return([:b, 'b'])
+
+      { a: 1 }.to_h { |k| x }.should == { :b => 'b' }
+    end
+
+    it "does not coerce returned pair to Array with #to_a" do
+      x = mock('x')
+      x.stub!(:to_a).and_return([:b, 'b'])
+
+      -> do
+        { a: 1 }.to_h { |k| x }
+      end.should.raise(TypeError, /wrong element type MockObject/)
+    end
+
+    it "does not retain the default value" do
+      h = Hash.new(1)
+      h2 = h.to_h { |k, v| [k.to_s, v*v]}
+      h2.default.should == nil
+    end
+
+    it "does not retain the default_proc" do
+      pr = proc { |h, k| h[k] = [] }
+      h = Hash.new(&pr)
+      h2 = h.to_h { |k, v| [k.to_s, v*v]}
+      h2.default_proc.should == nil
+    end
+
+    it "does not retain compare_by_identity flag" do
+      h = { a: 9, c: 4 }.compare_by_identity
+      h2 = h.to_h { |k, v| [k.to_s, v*v]}
+      h2.compare_by_identity?.should == false
+    end
+  end
+end