1 files changed, 65 insertions, 0 deletions
diff --git a/activesupport/test/core_ext/module/concerning_test.rb b/activesupport/test/core_ext/module/concerning_test.rb
new file mode 100644
index 0000000000..07d860b71c
--- /dev/null
+++ b/activesupport/test/core_ext/module/concerning_test.rb
@@ -0,0 +1,65 @@
+require 'abstract_unit'
+require 'active_support/core_ext/module/concerning'
+
+class ModuleConcerningTest < ActiveSupport::TestCase
+  def test_concerning_declares_a_concern_and_includes_it_immediately
+    klass = Class.new { concerning(:Foo) { } }
+    assert klass.ancestors.include?(klass::Foo), klass.ancestors.inspect
+  end
+end
+
+class ModuleConcernTest < ActiveSupport::TestCase
+  def test_concern_creates_a_module_extended_with_active_support_concern
+    klass = Class.new do
+      concern :Baz do
+        included { @foo = 1 }
+        def should_be_public; end
+      end
+    end
+
+    # Declares a concern but doesn't include it
+    assert klass.const_defined?(:Baz, false)
+    assert !ModuleConcernTest.const_defined?(:Baz)
+    assert_kind_of ActiveSupport::Concern, klass::Baz
+    assert !klass.ancestors.include?(klass::Baz), klass.ancestors.inspect
+
+    # Public method visibility by default
+    assert klass::Baz.public_instance_methods.map(&:to_s).include?('should_be_public')
+
+    # Calls included hook
+    assert_equal 1, Class.new { include klass::Baz }.instance_variable_get('@foo')
+  end
+
+  class Foo
+    concerning :Bar do
+      module ClassMethods
+        def will_be_orphaned; end
+      end
+
+      const_set :ClassMethods, Module.new {
+        def hacked_on; end
+      }
+
+      # Doesn't overwrite existing ClassMethods module.
+      class_methods do
+        def nicer_dsl; end
+      end
+
+      # Doesn't overwrite previous class_methods definitions.
+      class_methods do
+        def doesnt_clobber; end
+      end
+    end
+  end
+
+  def test_using_class_methods_blocks_instead_of_ClassMethods_module
+    assert !Foo.respond_to?(:will_be_orphaned)
+    assert Foo.respond_to?(:hacked_on)
+    assert Foo.respond_to?(:nicer_dsl)
+    assert Foo.respond_to?(:doesnt_clobber)
+
+    # Orphan in Foo::ClassMethods, not Bar::ClassMethods.
+    assert Foo.const_defined?(:ClassMethods)
+    assert Foo::ClassMethods.method_defined?(:will_be_orphaned)
+  end
+end