1 files changed, 48 insertions, 0 deletions
diff --git a/spec/ruby/core/hash/invert_spec.rb b/spec/ruby/core/hash/invert_spec.rb
new file mode 100644
index 0000000000..ea441751f2
--- /dev/null
+++ b/spec/ruby/core/hash/invert_spec.rb
@@ -0,0 +1,48 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Hash#invert" do
+  it "returns a new hash where keys are values and vice versa" do
+    { 1 => 'a', 2 => 'b', 3 => 'c' }.invert.should ==
+      { 'a' => 1, 'b' => 2, 'c' => 3 }
+  end
+
+  it "handles collisions by overriding with the key coming later in keys()" do
+    h = { a: 1, b: 1 }
+    override_key = h.keys.last
+    h.invert[1].should == override_key
+  end
+
+  it "compares new keys with eql? semantics" do
+    h = { a: 1.0, b: 1 }
+    i = h.invert
+    i[1.0].should == :a
+    i[1].should == :b
+  end
+
+  it "does not return subclass instances for subclasses" do
+    HashSpecs::MyHash[1 => 2, 3 => 4].invert.class.should == Hash
+    HashSpecs::MyHash[].invert.class.should == Hash
+  end
+
+  it "does not retain the default value" do
+    h = Hash.new(1)
+    h.invert.default.should == nil
+    h[:a] = 1
+    h.invert.default.should == nil
+  end
+
+  it "does not retain the default_proc" do
+    pr = proc { |h, k| h[k] = [] }
+    h = Hash.new(&pr)
+    h.invert.default_proc.should == nil
+    h[:a] = 1
+    h.invert.default_proc.should == nil
+  end
+
+  it "does not retain compare_by_identity flag" do
+    h = { a: 9, c: 4 }.compare_by_identity
+    h2 = h.invert
+    h2.compare_by_identity?.should == false
+  end
+end