Add method call assertions for internal use.

Add `assert_called` and `assert_not_called` to boil down the boilerplate we need to write
to assert methods are called certain number of times.

1 files changed, 30 insertions, 0 deletions

diff --git a/activesupport/lib/active_support/testing/method_call_assertions.rb b/activesupport/lib/active_support/testing/method_call_assertions.rb
new file mode 100644
index 0000000000..0d7d62341c
--- /dev/null
+++ b/activesupport/lib/active_support/testing/method_call_assertions.rb
@@ -0,0 +1,30 @@
+module ActiveSupport
+  module Testing
+    module MethodCallAssertions # :nodoc:
+      private
+        def assert_called(object, method_name, message = nil, times: 1)
+          times_called = 0
+
+          object.stub(method_name, -> { times_called += 1 }) { yield }
+
+          error = "Expected #{method_name} to be called #{times} times, " \
+            "but was called #{times_called} times"
+          error = "#{message}.\n#{error}" if message
+          assert_equal times, times_called, error
+        end
+
+        def assert_called_with(object, method_name, args = [], returns: nil)
+          mock = Minitest::Mock.new
+          mock.expect(:call, returns, args)
+
+          object.stub(method_name, mock) { yield }
+
+          mock.verify
+        end
+
+        def assert_not_called(object, method_name, message = nil, &block)
+          assert_called(object, method_name, message, times: 0, &block)
+        end
+    end
+  end
+end
\ No newline at end of file