RFC: Fix direction ALL test assertions org-wide with pytest approach changed in latest version

[pombredanne]

See
pytest-dev/pytest#3333
https://github.com/pytest-dev/pytest/pull/6673/files

In recent pytest versions 5.x+ the ways asserts failures are reported changed (rather dramatically if I may say) where the order is now:

• assert result == expected
  before and that was our org-wide convention we use the reverse:
• assert expected == result

This impacts significantly the way we look at test failures traces: the diffs are now unreadable and you need to make the mental switch that plus means minus and minus means plus to make sense of a failure trace.

I always thought that it is more natural to write assertion in this new way e.g. assert result == expected but that was never the convention in unittest, and pytest and related.
To recover sanity and assert again safely that plus == plus and minus=minus I suggest we adopt the way:

1. define a new org-wide standard to use ths way
2. progressively update ALL our many tests to use assert result == expected

As an example of the current problem here, this snippet is a failure trace where we expected an mit license_expression to be detected but instead an unknown license_expression was returned:

E                     "homepage_url": null,
E                     "keywords": [],
E         -           "license_expression": "unknown",
E         ?                                  ^^^^^^^
E         +           "license_expression": "mit",
E         ?                                  ^^^
E                     "md5": null,
E                     "name": "laravel",
E                     "namespace": "laravel",

Yet, the way this looks is that an unknown license was not detected and an mit was returned instead.
Before we bump to use pytest 5.x the same failure was looking this way:

E                     "homepage_url": null,
E                     "keywords": [],
E         -           "license_expression": "mit",
E         ?                                  ^^^
E         +           "license_expression": "unknown",
E         ?                                  ^^^^^^^
E                     "md5": null,
E                     "name": "laravel",
E                     "namespace": "laravel",

and this i how we want things to look again hence the push to reorder all our test assertions