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| -rw-r--r-- | doc/faq.rst | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/doc/faq.rst b/doc/faq.rst index ca795729..082ccbd1 100644 --- a/doc/faq.rst +++ b/doc/faq.rst @@ -11,7 +11,8 @@ FAQ and other help Frequently asked questions -------------------------- -**Q: Why do unexecutable lines show up as executed?** +Q: Why do unexecutable lines show up as executed? +................................................. Usually this is because you've updated your code and run coverage.py on it again without erasing the old data. Coverage.py records line numbers executed, @@ -22,22 +23,24 @@ If old data is persisting, you can use an explicit ``coverage erase`` command to clean out the old data. -**Q: Why do the bodies of functions (or classes) show as executed, but the def -lines do not?** +Q: Why do the bodies of functions show as executed, but the def lines do not? +............................................................................. This happens because coverage.py is started after the functions are defined. The definition lines are executed without coverage measurement, then coverage.py is started, then the function is called. This means the body is measured, but the definition of the function itself is not. +The same thing can happen with the bodies of classes. + To fix this, start coverage.py earlier. If you use the :ref:`command line <cmd>` to run your program with coverage.py, then your entire program will be monitored. If you are using the :ref:`API <api>`, you need to call coverage.start() before importing the modules that define your functions. -**Q: My decorator lines are marked as covered, but the "def" line is not. -Why?** +Q: My decorator lines are marked as covered, but the "def" line is not. Why? +............................................................................. Different versions of Python report execution on different lines. Coverage.py adapts its behavior to the version of Python being used. In Python 3.7 and @@ -47,7 +50,8 @@ reported. If you collect execution data on Python 3.7, and then run coverage reports on Python 3.8, there will be a discrepancy. -**Q: How is the total percentage calculated?** +Q: How is the total percentage calculated? +.......................................... Coverage.py counts the total number of possible executions. This is the number of executable statements minus the number of excluded statements. It then @@ -67,7 +71,8 @@ show the number of partial branches, which is the lines that were executed but did not execute all of their exits. -**Q: Coverage.py is much slower than I remember, what's going on?** +Q: Coverage.py is much slower than I remember, what's going on? +............................................................... Make sure you are using the C trace function. Coverage.py provides two implementations of the trace function. The C implementation runs much faster. @@ -80,7 +85,8 @@ Try re-installing coverage.py to see what happened and if you get the CTracer as you should. -**Q: Isn't coverage testing the best thing ever?** +Q: Isn't coverage testing the best thing ever? +.............................................. It's good, but `it isn't perfect`__. @@ -106,7 +112,8 @@ __ https://nedbatchelder.com/blog/200710/flaws_in_coverage_measurement.html .. _django-coverage: https://pypi.org/project/django-coverage/ -**Q: Where can I get more help with coverage.py?** +Q: Where can I get more help with coverage.py? +.............................................. You can discuss coverage.py or get help using it on the `Testing In Python`_ mailing list. |