FakeProcess doesn't respect universal_newlines

[bjornt]

FakeProcess always returns stdout.getvalue() and stderr.getvalue() as they are. This is a problem when you're testing code that sometimes passe universal_newlines to the subprocess calls.

In Python 2.7, universal_newlines doesn't make much of a difference, but in Python 3, if you pass universal_newlines=True, you will get strings instead of bytes for stdout and stderr in the subprocess calls.kaasjrzrrzr

[freeekanayaka]

I guess the solution would be make FakeProcess honor universal_newline and decode the bytes in that case?

[bjornt]

Yeah, I think that makes sense. Note that this should be done for Python 3 only. For Python 2 str is always returned, universal_newlines doesn't make a difference there.

Popen is tricky to fake. In another project I faked Popen I did so by creating temp scripts that wrote to stdout and stderr. That way I could use the real Popen to fake the output part by executing those scripts, so all subtle behaviors were taken care of the way the should.

[freeekanayaka]

@bjornt yes, I think both approaches (fake popen vs fake executables) make sense in different situations. You might have noticed already, but for there's support in systemfixtures for faking executables:

http://systemfixtures.readthedocs.io/en/latest/#executables

Depending on your situation you might prefer one or the other or a combination of both. Happy to help improving any rough edges you might find (either in FakePopen or FakeExecutable).