Running diff-quality with a tool which is not installed gives FIleNotFoundError rather than helpful "<tool> is not installed" error message

[dperl-dls]

Steps to reproduce:

• make an empy Python3.10 virtual environment
• install diff_cover
• navigate to a repo with something in the diff
• run e.g. diff-quality --violations=pydocstyle
  • Output: Failure: '[Errno 2] No such file or directory: 'pydocstyle''

Expected behaviour:

The output is instead Failure: 'pydocstyle is not installed'

Suggested resolution:

If diff_cover.command_runner.run_command_for_code is edited to be:

def run_command_for_code(command):
    """
    Returns command's exit code.
    """
    try:
        process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        process.communicate()
    except FileNotFoundError:
        return 1
    return process.returncode

Then the output is as expected. Setting shell=True in Popen equally works. See https://docs.python.org/3.11/library/subprocess.html#exceptions

Edit: I see this is actually a dupe of #303, sorry about that

[Bachmann1234]

I dont mind a dupe when Ican get more details (not to mention a pr).

Running the test suite now

[Bachmann1234]

@dperl-dls https://pypi.org/project/diff-cover/8.0.2/ is released with your PR in it. Thanks again!