1 files changed, 88 insertions, 0 deletions
diff --git a/spec/ruby/core/module/ancestors_spec.rb b/spec/ruby/core/module/ancestors_spec.rb
new file mode 100644
index 0000000000..f85884a4f3
--- /dev/null
+++ b/spec/ruby/core/module/ancestors_spec.rb
@@ -0,0 +1,88 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Module#ancestors" do
+  it "returns a list of modules included in self (including self)" do
+    BasicObject.ancestors.should == [BasicObject]
+    ModuleSpecs.ancestors.should == [ModuleSpecs]
+    ModuleSpecs::Basic.ancestors.should == [ModuleSpecs::Basic]
+    ModuleSpecs::Super.ancestors.should == [ModuleSpecs::Super, ModuleSpecs::Basic]
+    if defined?(Ruby::Box) && Ruby::Box.enabled?
+      ModuleSpecs.without_test_modules(ModuleSpecs::Parent.ancestors).should ==
+        [ModuleSpecs::Parent, Object, Ruby::Box::Loader, Kernel, BasicObject]
+      ModuleSpecs.without_test_modules(ModuleSpecs::Child.ancestors).should ==
+        [ModuleSpecs::Child, ModuleSpecs::Super, ModuleSpecs::Basic, ModuleSpecs::Parent, Object, Ruby::Box::Loader, Kernel, BasicObject]
+    else
+      ModuleSpecs.without_test_modules(ModuleSpecs::Parent.ancestors).should ==
+        [ModuleSpecs::Parent, Object, Kernel, BasicObject]
+      ModuleSpecs.without_test_modules(ModuleSpecs::Child.ancestors).should ==
+        [ModuleSpecs::Child, ModuleSpecs::Super, ModuleSpecs::Basic, ModuleSpecs::Parent, Object, Kernel, BasicObject]
+    end
+  end
+
+  it "returns only modules and classes" do
+    class << ModuleSpecs::Child; self; end.ancestors.to_set.should >= Set[ModuleSpecs::Internal, Class, Module, Object, Kernel]
+  end
+
+  it "has 1 entry per module or class" do
+    ModuleSpecs::Parent.ancestors.should == ModuleSpecs::Parent.ancestors.uniq
+  end
+
+  it "returns a module that is included later into a nested module as well" do
+    m1 = Module.new
+    m2 = Module.new
+    m3 = Module.new do
+      include m2
+    end
+    m2.include m1 # should be after m3 includes m2
+
+    m3.ancestors.should == [m3, m2, m1]
+  end
+
+  describe "when called on a singleton class" do
+    it "includes the singleton classes of ancestors" do
+      parent  = Class.new
+      child   = Class.new(parent)
+      schild  = child.singleton_class
+
+      schild.ancestors.to_set.should >= Set[schild,
+                                      parent.singleton_class,
+                                      Object.singleton_class,
+                                      BasicObject.singleton_class,
+                                      Class,
+                                      Module,
+                                      Object,
+                                      Kernel,
+                                      BasicObject]
+
+    end
+
+    describe 'for a standalone module' do
+      it 'does not include Class' do
+        s_mod = ModuleSpecs.singleton_class
+        s_mod.ancestors.should_not.include?(Class)
+      end
+
+      it 'does not include other singleton classes' do
+        s_standalone_mod = ModuleSpecs.singleton_class
+        s_module = Module.singleton_class
+        s_object = Object.singleton_class
+        s_basic_object = BasicObject.singleton_class
+
+        (s_standalone_mod.ancestors & [s_module, s_object, s_basic_object]).should.empty?
+      end
+
+      it 'includes its own singleton class' do
+        s_mod = ModuleSpecs.singleton_class
+
+        s_mod.ancestors.should.include?(s_mod)
+      end
+
+      it 'includes standard chain' do
+        s_mod = ModuleSpecs.singleton_class
+
+        s_mod.ancestors.to_set.should >= Set[Module, Object, Kernel, BasicObject]
+      end
+    end
+  end
+end