Create ActiveSupport::Testing::ConstantLookup

AS::TC::ConstantLookup walks the test's name to find the constant it is describing.
This additional lookup logic is needed to better support minitest's spec DSL.

1 files changed, 53 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/testing/constant_lookup.rb b/activesupport/lib/active_support/testing/constant_lookup.rb
new file mode 100644
index 0000000000..8cb84b3f20
--- /dev/null
+++ b/activesupport/lib/active_support/testing/constant_lookup.rb
@@ -0,0 +1,53 @@
+require "active_support/concern"
+
+module ActiveSupport
+  module Testing
+    # Resolves a constant from a minitest spec name.
+    #
+    # Given the following spec-style test:
+    #
+    #   describe WidgetsController, :index do
+    #     describe "authenticated user" do
+    #       describe "returns widgets" do
+    #         it "has a controller that exists" do
+    #           assert_kind_of WidgetsController, @controller
+    #         end
+    #       end
+    #     end
+    #   end
+    #
+    # The test will have the following name:
+    #
+    #   "WidgetsController::index::authenticated user::returns widgets"
+    #
+    # The constant WidgetsController can be resolved from the name.
+    # The following code will resolve the constant:
+    #
+    #   controller = determine_constant_from_test_name(name) do |constant|
+    #     Class === constant && constant < ::ActionController::Metal
+    #   end
+    module ConstantLookup
+      extend ::ActiveSupport::Concern
+
+      module ClassMethods
+        def determine_constant_from_test_name(test_name)
+          names = test_name.split "::"
+          while names.size > 0 do
+            names.last.sub! /Test$/, ""
+            # Rails 3.0 doesn't have safe_constantize,
+            # so we'll do it the hard way.
+            begin
+              constant = names.join("::").constantize
+              break(constant) if yield(constant)
+            rescue NameError
+              # Constant wasn't found, move on
+            ensure
+              names.pop
+            end
+          end
+        end
+      end
+
+    end
+  end
+end