trailing newline in str comparison is hard to spot

[jugmac00]

testtools

$ python test_diff.py 
F
======================================================================
FAIL: test_newline (__main__.TestNewline)
__main__.TestNewline.test_newline
----------------------------------------------------------------------
testtools.testresult.real._StringException: Traceback (most recent call last):
  File "test_diff.py", line 11, in test_newline
    self.assertEqual(
  File "/tmp/venv/lib/python3.8/site-packages/testtools/testcase.py", line 393, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/tmp/venv/lib/python3.8/site-packages/testtools/testcase.py", line 480, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: !=:
reference = '''\
INFO Requesting CI build for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64
'''
actual    = 'INFO Requesting CI build for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64'

unittest

$ python test_diff.py 
F
======================================================================
FAIL: test_newline (__main__.TestNewline)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test_diff.py", line 11, in test_newline
    "INFO Requesting CI build for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64"
AssertionError: 'INFO[21 chars]for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64\n' != 'INFO[21 chars]for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64'
- INFO Requesting CI build for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64
?                                                                                      -
+ INFO Requesting CI build for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64

pytest

$ pytest test_diff.py 
======================================== test session starts ========================================
platform linux -- Python 3.8.10, pytest-7.0.1, pluggy-1.0.0
rootdir: /tmp
collected 1 item                                                                                    

test_diff.py F                                                                                [100%]

============================================= FAILURES ==============================================
_____________________________________ TestNewline.test_newline ______________________________________

self = <test_diff.TestNewline testMethod=test_newline>

    def test_newline(self):
>       self.assertEqual(
            newline(),
            "INFO Requesting CI build for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64"
        )
E       AssertionError: 'INFO[21 chars]for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64\n' != 'INFO[21 chars]for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64'
E       - INFO Requesting CI build for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64
E       ?                                                                                      -
E       + INFO Requesting CI build for  972c6d2dc6dd5efdad1377c0d224e03eb8f276f7 on focal/amd64

test_diff.py:11: AssertionError

Both unittest and pytest indicate what the problem is, but testtools only shows a rather unfortunate multiline representation of the string.