1 files changed, 61 insertions, 0 deletions
diff --git a/spec/ruby/core/module/append_features_spec.rb b/spec/ruby/core/module/append_features_spec.rb
new file mode 100644
index 0000000000..1724cde5d6
--- /dev/null
+++ b/spec/ruby/core/module/append_features_spec.rb
@@ -0,0 +1,61 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Module#append_features" do
+  it "is a private method" do
+    Module.should have_private_instance_method(:append_features)
+  end
+
+  describe "on Class" do
+    it "is undefined" do
+      Class.should_not have_private_instance_method(:append_features, true)
+    end
+
+    it "raises a TypeError if calling after rebinded to Class" do
+      -> {
+        Module.instance_method(:append_features).bind(Class.new).call Module.new
+      }.should raise_error(TypeError)
+    end
+  end
+
+  it "gets called when self is included in another module/class" do
+    begin
+      m = Module.new do
+        def self.append_features(mod)
+          $appended_to = mod
+        end
+      end
+
+      c = Class.new do
+        include m
+      end
+
+      $appended_to.should == c
+    ensure
+      $appended_to = nil
+    end
+  end
+
+  it "raises an ArgumentError on a cyclic include" do
+    -> {
+      ModuleSpecs::CyclicAppendA.send(:append_features, ModuleSpecs::CyclicAppendA)
+    }.should raise_error(ArgumentError)
+
+    -> {
+      ModuleSpecs::CyclicAppendB.send(:append_features, ModuleSpecs::CyclicAppendA)
+    }.should raise_error(ArgumentError)
+
+  end
+
+  describe "when other is frozen" do
+    before :each do
+      @receiver = Module.new
+      @other = Module.new.freeze
+    end
+
+    it "raises a FrozenError before appending self" do
+      -> { @receiver.send(:append_features, @other) }.should raise_error(FrozenError)
+      @other.ancestors.should_not include(@receiver)
+    end
+  end
+end