python config_error ai_generated true

AssertionError: assert 'expected message' in [] where [] = caplog.messages

ID: python/pytest-caplog-not-captured

Also available as: JSON · Markdown · 中文
80%Fix Rate
85%Confidence
0Evidence
2024-10-03First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
7.x active — — —
8.x active — — —

Root Cause

The logger used by the code under test has propagate=False, or logging was configured with a handler that bypasses the root logger, so caplog's root handler never receives the record.

generic

中文

被测代码使用的 logger 设置了 propagate=False，或日志配置使用了绕过根 logger 的 handler，导致 caplog 的根 handler 从未收到日志记录。

Workarounds

  1. 90% success 
    def test_x(caplog):
    logging.getLogger('myapp').propagate = True
    with caplog.at_level(logging.INFO, logger='myapp'):
        run()
    assert 'expected message' in caplog.text
  2. 92% success 
    import logging

def test_x():
    records = []
    h = logging.Handler()
    h.emit = records.append
    log = logging.getLogger('myapp')
    log.addHandler(h)
    try:
        run()
    finally:
        log.removeHandler(h)
    assert any('expected' in r.getMessage() for r in records)

Dead Ends

Common approaches that don't work:

  1. 85% fail

    Level is not the issue if propagate=False; the record never reaches the root logger's handlers regardless of level.

  2. 90% fail

    Both attributes are populated from the same captured records; an empty capture yields empty results in either.