Add specs for Hash.ruby2_keywords_hash? and Hash.ruby2_keywords_hash

Author: eregon

spec/ruby/core/hash/ruby2_keywords_hash_spec.rb

@@ -0,0 +1,47 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+ruby_version_is "2.7" do
+  describe "Hash.ruby2_keywords_hash?" do
+    it "returns false if the Hash is not a keywords Hash" do
+      Hash.ruby2_keywords_hash?({}).should == false
+    end
+
+    it "returns true if the Hash is a keywords Hash" do
+      obj = Class.new {
+        ruby2_keywords def m(*args)
+          args.last
+        end
+      }.new
+      Hash.ruby2_keywords_hash?(obj.m(a: 1)).should == true
+    end
+
+    it "raises TypeError for non-Hash" do
+      -> { Hash.ruby2_keywords_hash?(nil) }.should raise_error(TypeError)
+    end
+  end
+
+  describe "Hash.ruby2_keywords_hash" do
+    it "returns a copy of a Hash and marks the copy as a keywords Hash" do
+      h = {a: 1}.freeze
+      kw = Hash.ruby2_keywords_hash(h)
+      Hash.ruby2_keywords_hash?(h).should == false
+      Hash.ruby2_keywords_hash?(kw).should == true
+      kw.should == h
+    end
+
+    it "returns an instance of the subclass if called on an instance of a subclass of Hash" do
+      h = HashSpecs::MyHash.new
+      h[:a] = 1
+      kw = Hash.ruby2_keywords_hash(h)
+      kw.class.should == HashSpecs::MyHash
+      Hash.ruby2_keywords_hash?(h).should == false
+      Hash.ruby2_keywords_hash?(kw).should == true
+      kw.should == h
+    end
+
+    it "raises TypeError for non-Hash" do
+      -> { Hash.ruby2_keywords_hash(nil) }.should raise_error(TypeError)
+    end
+  end
+end

spec/tags/core/hash/ruby2_keywords_hash_tags.txt

@@ -0,0 +1,6 @@
+fails:Hash.ruby2_keywords_hash? returns false if the Hash is not a keywords Hash
+fails:Hash.ruby2_keywords_hash? returns true if the Hash is a keywords Hash
+fails:Hash.ruby2_keywords_hash? raises TypeError for non-Hash
+fails:Hash.ruby2_keywords_hash returns a copy of a Hash and marks the copy as a keywords Hash
+fails:Hash.ruby2_keywords_hash raises TypeError for non-Hash
+fails:Hash.ruby2_keywords_hash returns an instance of the subclass if called on an instance of a subclass of Hash