Explain Pytest Assertion With Expected Data Last as Opposed to First

pytest-output.txt

===================================================================================================== FAILURES ======================================================================================================
________________________________________________________________________________________________ test_expected_first ________________________________________________________________________________________________

    def test_expected_first():
        expected = {
            "one": 1,
            "two": 2,
        }
        ret = {
            "one": 1,
            "two": 2,
            "three": 3,
        }
>       assert expected == ret
E       AssertionError: assert {'one': 1, 'two': 2} == {'one': 1, 'two': 2, 'three': 3}
E         Common items:
E         {'one': 1, 'two': 2}
E         Right contains 1 more item:
E         {'three': 3}
E         Full diff:
E         - {'one': 1, 'three': 3, 'two': 2}
E         ?           ------------
E         + {'one': 1, 'two': 2}

expected   = {'one': 1, 'two': 2}
ret        = {'one': 1, 'three': 3, 'two': 2}

tests/pytests/unit/test_diff.py:12: AssertionError
________________________________________________________________________________________________ test_expected_last _________________________________________________________________________________________________

    def test_expected_last():
        expected = {
            "one": 1,
            "two": 2,
        }
        ret = {
            "one": 1,
            "two": 2,
            "three": 3,
        }
>       assert ret == expected
E       AssertionError: assert {'one': 1, 'two': 2, 'three': 3} == {'one': 1, 'two': 2}
E         Common items:
E         {'one': 1, 'two': 2}
E         Left contains 1 more item:
E         {'three': 3}
E         Full diff:
E         - {'one': 1, 'two': 2}
E         + {'one': 1, 'three': 3, 'two': 2}
E         ?           ++++++++++++

expected   = {'one': 1, 'two': 2}
ret        = {'one': 1, 'three': 3, 'two': 2}

tests/pytests/unit/test_diff.py:24: AssertionError
---------------------------------------- generated xml file: /home/vampas/projects/SaltStack/salt/hotfix/merge-forward/artifacts/xml-unittests-output/test-results-grp1.xml -----------------------------------------
============================================================================================== short test summary info ==============================================================================================
FAILED tests/pytests/unit/test_diff.py::test_expected_first - AssertionError: assert {'one': 1, 'two': 2} == {'one': 1, 'two': 2, 'three': 3}
FAILED tests/pytests/unit/test_diff.py::test_expected_last - AssertionError: assert {'one': 1, 'two': 2, 'three': 3} == {'one': 1, 'two': 2}
================================================================================================= 2 failed in 1.03s =================================================================================================

test_diff.py

def test_expected_first():
    expected = {
        "one": 1,
        "two": 2,
    }
    ret = {
        "one": 1,
        "two": 2,
        "three": 3,
    }
    assert expected == ret

def test_expected_last():
    expected = {
        "one": 1,
        "two": 2,
    }
    ret = {
        "one": 1,
        "two": 2,
        "three": 3,
    }
    assert ret == expected