1 files changed, 38 insertions, 0 deletions
diff --git a/lib/minitest/mock.rb b/lib/minitest/mock.rb
index 55b0095c0b..ec36d775cc 100644
--- a/lib/minitest/mock.rb
+++ b/lib/minitest/mock.rb
@@ -132,3 +132,41 @@ module MiniTest
     end
   end
 end
+
+class Object # :nodoc:
+
+  ##
+  # Add a temporary stubbed method replacing +name+ for the duration
+  # of the +block+. If +val_or_callable+ responds to #call, then it
+  # returns the result of calling it, otherwise returns the value
+  # as-is. Cleans up the stub at the end of the +block+.
+  #
+  #     def test_stale_eh
+  #       obj_under_test = Something.new
+  #       refute obj_under_test.stale?
+  #
+  #       Time.stub :now, Time.at(0) do
+  #         assert obj_under_test.stale?
+  #       end
+  #     end
+
+  def stub name, val_or_callable, &block
+    new_name = "__minitest_stub__#{name}"
+
+    metaclass = class << self; self; end
+    metaclass.send :alias_method, new_name, name
+    metaclass.send :define_method, name do |*args|
+      if val_or_callable.respond_to? :call then
+        val_or_callable.call(*args)
+      else
+        val_or_callable
+      end
+    end
+
+    yield
+  ensure
+    metaclass.send :undef_method, name
+    metaclass.send :alias_method, name, new_name
+    metaclass.send :undef_method, new_name
+  end
+end