New cop: Minitest/TestFileName

[fatkodima]

This cop should check if we have a test class inside the file without the _test suffix.
In this case, this file will be just ignored when running all the tests and go unnoticed.

[koic]

Can you point out bad and good cases with code?

[fatkodima]

Bad

# Defined in test/something.rb file
class SomethingTest < Minitest::Test
  def test_foo
    # ...
  end
end

Good

# Defined in test/something_test.rb file
class SomethingTest < Minitest::Test
  def test_foo
    # ...
  end
end

[tejasbubane]

I guess this cop will be very similar to RSpec/FilePath.

[fatkodima]

Yes. Rspec's cop enforces that the file is named as a tested class also (besides the suffix). In minitest, sometimes in a single test file there are multiple test classes (a rails/rails is a good example). So I would not enforce that, or maybe under some flag.

[andyw8]

I added a guideline relating to this to the styleguide a while ago:

https://github.com/rubocop/minitest-style-guide#file-naming

And I just opened this PR:
rubocop/minitest-style-guide#52

[andyw8]

(Brief reply as I'm on mobile). The naming convention could be configurable, to avoid the risk of the file name not matching an expected pattern, e.g. *_test