There are two main reasons why `assert_called_with` should require
`args` argument:

1) If we want to assert that some method should be called and we don't
   need to check with which arguments it should be called then we should use
   `assert_called`.

2) `assert_called_with` without `args` argument doesn't assert anything!
   ```ruby
   assert_called_with(@object, :increment) do
      @object.decrement
   end
   ```
   It causes false assertions in tests that could cause regressions in the project.

I found this bug by working on
[minitest-mock_expectations](https://github.com/bogdanvlviv/minitest-mock_expectations) gem.
This gem is an extension for minitest that provides almost the same method call
assertions.
I was wondering whether you would consider adding "minitest-mock_expectations"
to `rails/rails` instead of private `ActiveSupport::Testing::MethodCallAssertions` module.
If yes, I'll send a patch - https://github.com/bogdanvlviv/rails/commit/a970ecc42c3a9637947599f2c13e3762e4b59208