1 files changed, 64 insertions, 0 deletions
diff --git a/spec/ruby/core/module/prepend_features_spec.rb b/spec/ruby/core/module/prepend_features_spec.rb
new file mode 100644
index 0000000000..3a50f2c2a4
--- /dev/null
+++ b/spec/ruby/core/module/prepend_features_spec.rb
@@ -0,0 +1,64 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Module#prepend_features" do
+  it "is a private method" do
+    Module.private_instance_methods(false).should.include?(:prepend_features)
+  end
+
+  it "gets called when self is included in another module/class" do
+    ScratchPad.record []
+
+    m = Module.new do
+      def self.prepend_features(mod)
+        ScratchPad << mod
+      end
+    end
+
+    c = Class.new do
+      prepend m
+    end
+
+    ScratchPad.recorded.should == [c]
+  end
+
+  it "raises an ArgumentError on a cyclic prepend" do
+    -> {
+      ModuleSpecs::CyclicPrepend.send(:prepend_features, ModuleSpecs::CyclicPrepend)
+    }.should.raise(ArgumentError)
+  end
+
+  it "clears caches of the given module" do
+    parent = Class.new do
+      def bar; :bar; end
+    end
+
+    child = Class.new(parent) do
+      def foo; :foo; end
+      def bar; super; end
+    end
+
+    mod = Module.new do
+      def foo; :fooo; end
+    end
+
+    child.new.foo
+    child.new.bar
+
+    child.prepend(mod)
+
+    child.new.bar.should == :bar
+  end
+
+  describe "on Class" do
+    it "is undefined" do
+      Class.private_instance_methods(true).should_not.include?(:prepend_features)
+    end
+
+    it "raises a TypeError if calling after rebinded to Class" do
+      -> {
+        Module.instance_method(:prepend_features).bind(Class.new).call Module.new
+      }.should.raise(TypeError)
+    end
+  end
+end