1 files changed, 36 insertions, 0 deletions
diff --git a/spec/ruby/core/module/comparison_spec.rb b/spec/ruby/core/module/comparison_spec.rb
new file mode 100644
index 0000000000..86ee5db22a
--- /dev/null
+++ b/spec/ruby/core/module/comparison_spec.rb
@@ -0,0 +1,36 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+
+describe "Module#<=>" do
+  it "returns -1 if self is a subclass of or includes the given module" do
+    (ModuleSpecs::Child <=> ModuleSpecs::Parent).should == -1
+    (ModuleSpecs::Child <=> ModuleSpecs::Basic).should == -1
+    (ModuleSpecs::Child <=> ModuleSpecs::Super).should == -1
+    (ModuleSpecs::Super <=> ModuleSpecs::Basic).should == -1
+  end
+
+  it "returns 0 if self is the same as the given module" do
+    (ModuleSpecs::Child  <=> ModuleSpecs::Child).should == 0
+    (ModuleSpecs::Parent <=> ModuleSpecs::Parent).should == 0
+    (ModuleSpecs::Basic  <=> ModuleSpecs::Basic).should == 0
+    (ModuleSpecs::Super  <=> ModuleSpecs::Super).should == 0
+  end
+
+  it "returns +1 if self is a superclass of or included by the given module" do
+    (ModuleSpecs::Parent <=> ModuleSpecs::Child).should == +1
+    (ModuleSpecs::Basic  <=> ModuleSpecs::Child).should == +1
+    (ModuleSpecs::Super  <=> ModuleSpecs::Child).should == +1
+    (ModuleSpecs::Basic  <=> ModuleSpecs::Super).should == +1
+  end
+
+  it "returns nil if self and the given module are not related" do
+    (ModuleSpecs::Parent <=> ModuleSpecs::Basic).should == nil
+    (ModuleSpecs::Parent <=> ModuleSpecs::Super).should == nil
+    (ModuleSpecs::Basic  <=> ModuleSpecs::Parent).should == nil
+    (ModuleSpecs::Super  <=> ModuleSpecs::Parent).should == nil
+  end
+
+  it "returns nil if the argument is not a class/module" do
+    (ModuleSpecs::Parent <=> mock('x')).should == nil
+  end
+end