Remove newlines from left/right operands with '-vv'

[samuelcolvin]

fix #9742

I've done this in the least intrusive way possible, a cleaner solution would be to alter saferepr to behave like the new saferepr_unlimited method when maxsize=None, but that might effect some other code (though I think use of saferepr() with maxsize=None is very rare).

[Zac-HD]

Thanks @samuelcolvin - this looks good to me, though I'll leave merging to another maintainer to be sure 🙂

[nicoddemus]

Here's the output of main:

 λ pytest .tmp\test_foo.py -vv --no-header
======================== test session starts ========================
collected 1 item

.tmp\test_foo.py::test_foobar FAILED                           [100%]

============================= FAILURES ==============================
____________________________ test_foobar ____________________________

    def test_foobar():
        a = {string.ascii_letters[i]: i for i in range(26)}
        b = a.copy()
        a.pop('g')
>       assert a == b
E       AssertionError: assert {'a': 0,\n 'b': 1,\n 'c': 2,\n 'd': 3,\n 'e': 4,\n 'f': 5,\n 'h': 7,\n 'i': 8,\n 'j': 9,\n 'k': 10,\n 'l': 11,\n 'm': 12,\n 'n': 13,\n 'o': 14,\n 'p': 15,\n 'q': 16,\n 'r': 17,\n 's': 18,\n 't': 19,\n 'u': 20,\n 'v': 21,\n 'w': 22,\n 'x': 23,\n 'y': 24,\n 'z': 25} == {'a': 0,\n 'b': 1,\n 'c': 2,\n 'd': 3,\n 'e': 4,\n 'f': 5,\n 'g': 6,\n 'h': 7,\n 'i': 8,\n 'j': 9,\n 'k': 10,\n 'l': 11,\n 'm': 12,\n 'n': 13,\n 'o': 14,\n 'p': 15,\n 'q': 16,\n 'r': 17,\n 's': 18,\n 't': 19,\n 'u': 20,\n 'v': 21,\n 'w': 22,\n 'x': 23,\n 'y': 24,\n 'z': 25}
E         Common items:
E         {'a': 0,
E          'b': 1,
E          'c': 2,
E          'd': 3,
E          'e': 4,
E          'f': 5,
E          'h': 7,
E          'i': 8,
E          'j': 9,
E          'k': 10,
E          'l': 11,
E          'm': 12,
E          'n': 13,
E          'o': 14,
E          'p': 15,
E          'q': 16,
E          'r': 17,
E          's': 18,
E          't': 19,
E          'u': 20,
E          'v': 21,
E          'w': 22,
E          'x': 23,
E          'y': 24,
E          'z': 25}
E         Right contains 1 more item:
E         {'g': 6}
E         Full diff:
E           {
E            'a': 0,
E            'b': 1,
E            'c': 2,
E            'd': 3,
E            'e': 4,
E            'f': 5,
E         -  'g': 6,
E            'h': 7,
E            'i': 8,
E            'j': 9,
E            'k': 10,
E            'l': 11,
E            'm': 12,
E            'n': 13,
E            'o': 14,
E            'p': 15,
E            'q': 16,
E            'r': 17,
E            's': 18,
E            't': 19,
E            'u': 20,
E            'v': 21,
E            'w': 22,
E            'x': 23,
E            'y': 24,
E            'z': 25,
E           }

.tmp\test_foo.py:8: AssertionError
====================== short test summary info ======================
FAILED .tmp\test_foo.py::test_foobar - AssertionError: assert {'a':...
========================= 1 failed in 0.11s =========================

And here's the output of this PR:

λ pytest .tmp\test_foo.py -vv --no-header
======================== test session starts ========================
collected 1 item

.tmp\test_foo.py::test_foobar FAILED                           [100%]

============================= FAILURES ==============================
____________________________ test_foobar ____________________________

    def test_foobar():
        a = {string.ascii_letters[i]: i for i in range(26)}
        b = a.copy()
        a.pop('g')
>       assert a == b
E       AssertionError: assert {'a': 0, 'b': 1, 'c': 2, 'd': 3, 'e': 4, 'f': 5, 'h': 7, 'i': 8, 'j': 9, 'k': 10, 'l': 11, 'm': 12, 'n': 13, 'o': 14, 'p': 15, 'q': 16, 'r': 17, 's': 18, 't': 19, 'u': 20, 'v': 21, 'w': 22, 'x': 23, 'y': 24, 'z': 25} == {'a': 0, 'b': 1, 'c': 2, 'd': 3, 'e': 4, 'f': 5, 'g': 6, 'h': 7, 'i': 8, 'j': 9, 'k': 10, 'l': 11, 'm': 12, 'n': 13, 'o': 14, 'p': 15, 'q': 16, 'r': 17, 's': 18, 't': 19, 'u': 20, 'v': 21, 'w': 22, 'x': 23, 'y': 24, 'z': 25}
E         Common items:
E         {'a': 0,
E          'b': 1,
E          'c': 2,
E          'd': 3,
E          'e': 4,
E          'f': 5,
E          'h': 7,
E          'i': 8,
E          'j': 9,
E          'k': 10,
E          'l': 11,
E          'm': 12,
E          'n': 13,
E          'o': 14,
E          'p': 15,
E          'q': 16,
E          'r': 17,
E          's': 18,
E          't': 19,
E          'u': 20,
E          'v': 21,
E          'w': 22,
E          'x': 23,
E          'y': 24,
E          'z': 25}
E         Right contains 1 more item:
E         {'g': 6}
E         Full diff:
E           {
E            'a': 0,
E            'b': 1,
E            'c': 2,
E            'd': 3,
E            'e': 4,
E            'f': 5,
E         -  'g': 6,
E            'h': 7,
E            'i': 8,
E            'j': 9,
E            'k': 10,
E            'l': 11,
E            'm': 12,
E            'n': 13,
E            'o': 14,
E            'p': 15,
E            'q': 16,
E            'r': 17,
E            's': 18,
E            't': 19,
E            'u': 20,
E            'v': 21,
E            'w': 22,
E            'x': 23,
E            'y': 24,
E            'z': 25,
E           }

.tmp\test_foo.py:8: AssertionError
====================== short test summary info ======================
FAILED .tmp\test_foo.py::test_foobar - AssertionError: assert {'a':...
========================= 1 failed in 0.09s =========================

So clearly an improvement! 👍

[nicoddemus]

Thanks @samuelcolvin, appreciate a lot the PR! Very clean work. 👍

[nicoddemus]

Indeed using safeformat for the left and right operands when verbose > 1 is not what is expected, because safeformat introduces newlines, and the result of assertrepr_compare is expected to be a list of lines; the string produced by safeformat (containing \n) is put as a single string in the result, which causes them to be escaped by the terminal later (I assume).

So the fix is entirely correct: use repr to produce the representation without \n, which is used to build the summary variable which is expected to be a single line.