There are several issues with error reports when doctests are wrapped in DocTestCase.

• When error happens during compilation or execution an example, the traceback contains several lines from doctest.py:

      File ...
        exec(compile(example.source, filename, "single",
        ~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                     compileflags, True), test.globs)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  

• When the output differs, the traceback of AssertionError contains other line from doctest.py:

    Traceback (most recent call last):
      File ...
        raise self.failureException(self.format_failure(new.getvalue()))
  

• Also, the AssertionError message contains redundant newline character.

Linked PRs

• gh-134857: Improve error report for doctests run with unittest #134858
• [3.14] gh-134857: Improve error report for doctests run with unittest (GH-134858) #134903