I've had a few reviews recommending the use of np.testing.assert_allclose() (or was it assert np.allclose()?) instead of assert_array_almost_equal but there doesn't seem to be a consensus (#13130 (comment)).

Also the use of assert_equal seems to be "deprecated" in favor of assert . == . (https://github.com/scikit-learn/scikit-learn/pull/13174/files#r257524501)

So, let's all agree on how we should write tests? I'll update the dev guide with the new decisions