python runtime_error ai_generated true

AssertionError: ValueError not raised

ID: python/unittest-assertraises-no-exception

Also available as: JSON · Markdown · 中文
80%Fix Rate
88%Confidence
0Evidence
2024-02-27First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.10 active — — —
3.11 active — — —
3.12 active — — —

Root Cause

self.assertRaises(ValueError) was used as a context manager but the code under test did not raise, or the exception was caught and swallowed inside the function.

generic

中文

self.assertRaises(ValueError) 作为上下文管理器使用，但被测代码未引发异常，或异常在函数内部被捕获并吞掉。

Workarounds

  1. 90% success 
    with self.assertRaises(ValueError) as ctx:
    parse('bad-input')
self.assertIn('bad-input', str(ctx.exception))
  2. 92% success 
    import pytest

def test_parse_raises():
    with pytest.raises(ValueError, match=r'bad-input'):
        parse('bad-input')

Dead Ends

Common approaches that don't work:

  1. 85% fail

    Inverts the logic: except catches the expected exception and calls fail, so a correct raise now fails the test.

  2. 75% fail

    Broadens the assertion so much that any unrelated error (e.g. TypeError) passes the test, masking real bugs.