Resolve a "FIXME" on why inspect.ismethod() did not work.

[iulianmac]

What:

Debug why inspect.ismethod() did not work in cli.py and update steps in contribution guide on building the docker image for development.

Why:

Resolves a FIXME comment and updates development guide on building Docker image for dev.

How:

Executed all unit-tests.

Done the following small test:

import inspect

class C(object):
    def foo(self):
        pass

>>> callable(getattr(C, "foo")) # What is now in code
True
>>> inspect.ismethod(getattr(C, "foo")) # Probably what caused the "FIXME" comment
False
>>> inspect.ismethod(getattr(C(), "foo")) # Propsed fix
True

Probably because inspect.ismethod() Return True if the object is a bound method written in Python.

>>> C.foo
<function C.foo at 0x104aa6ca0>
>>> C().foo
<bound method C.foo of <__main__.C object at 0x104ab87f0>>

Risks:

Potential cases not covered by unit-tests today.

Checklist:

• Added tests, if you've added code that should be tested (N/A)
• Updated the documentation, if you've changed APIs (N/A)
• Ensured the test suite passes
• Made sure your code lints
• Completed the Contributor License Agreement ("CLA")

[iulianmac]

Seems that CI is failing for Python3.6 but looks unrelated to my changes. I was able to reproduce the failing case from "main" branch as well with python3.6.

>       assert "passed, 4 errors" in result.stdout.str()
E       AssertionError: assert 'passed, 4 errors' in ''
E        +  where '' = <bound method LineMatcher.str of <_pytest.pytester.LineMatcher object at 0xffffac8979e8>>()
E        +    where <bound method LineMatcher.str of <_pytest.pytester.LineMatcher object at 0xffffac8979e8>> = <_pytest.pytester.LineMatcher object at 0xffffac8979e8>.str
E        +      where <_pytest.pytester.LineMatcher object at 0xffffac8979e8> = <RunResult ret=ExitCode.USAGE_ERROR len(stdout.lines)=0 len(stderr.lines)=5 duration=0.02s>.stdout

/root/src/TestSlide/pytest-testslide/tests/test_pytest_testslide.py:129: AssertionError

[iulianmac]

I've put out #332 as an attempt to fix CI tests.

[facebook-github-bot]

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