Adding a dry run flag

[seemethere]

Adds a --dry-run flag that outputs all output to stdout.

Example usage:

$ undebt -p undebt/examples/method_to_function.py  -i tests/inputs/method_to_function_input.txt --dry-run

Example output:

>>> tests/inputs/method_to_function_input.txt
from function_lives_here import function
something before code pattern
@decorator([Class])
def some_function(self, abc, xyz):
    """herp the derp while also derping and herping"""
    cde = fgh(self.l)
    ijk = cde.herp(
        opq_foo=function(FOO(abc))
    )['str']
    lmn = cde.herp(
        opq_foo=function(FOO(xyz))
    )['str']
bla bla bla
    for str_data in derp_data['data']['strs']:
        if str_data['str'] == Type.HERP:
            disable(herp_foo=herp_foo, derp_foo=derp_foo)
            rst.uvw(
                CTA_BUSINESS_PLATFORM_DISABLED_LOG,
                "derp {derp_foo} herp {herp_foo}".format(
                    derp_foo=function(FOO(derp_foo)),
                    herp_foo=function(FOO(herp_foo)),
                ),
            )
something after code pattern

Related to issue #3

[evhub]

@seemethere Looks good! One major thing, though—it'd be nice to have some tests for this. Can you add a test to main_test.py that uses --dry-run? Then run make test to ensure it (and all the other tests) are passing.

[seemethere]

@evhub I was just thinking about that too!

[coveralls]

Changes Unknown when pulling 2df4c11 on seemethere:dry_run into * on Yelp:master*.

[seemethere]

@evhub Tests have been added!

[evhub]

I'd rather not add a new dependency just to get StringIO. Can you do

try:
    from io import StringIO
except ImportError:
    from StringIO import StringIO

instead?

[ajm188]

Isn't that exactly what six does?

I agree with leaning against adding dependencies, but six seems to be a pretty standard one, especially for ensuring 2/3 compat

[evhub]

Yeah, fair point—I retract my request to remove six. If we're using six here, though, we should probably use it elsewhere also—but I can take care of that after this is merged.

[asottile]

imo use six, it's what it's for

But in this case you can avoid it entirely, I'll comment below :D

[asottile]

and actually, this is just a test so it shouldn't have been added as a dependency in setup.py (setup.py is for runtime dependencies, whereas this is a test-time dependency (and therefore belongs in requirements-dev.txt))

[evhub]

LGTM!

@asottile Do you want to weigh in here before I merge this?

[asottile]

you want the capsys pytest fixture: http://doc.pytest.org/en/latest/capture.html#accessing-captured-output-from-a-test-function

[asottile]

@asottile Do you want to weigh in here before I merge this?

eheh, didn't meant to get terribly involved in the project but sure :D

[Daenyth]

I haven't used undebt yet, but one thing that would make this specific thing more useful to me is a diff-mode output. As it stands, I'd have to either not use the dry run option and use git for my diff, or I use dry run, and pipe it to a file to diff manually.

[asottile]

@Daenyth that's a great idea. Most of these fixer type tools (especially the ones we use with pre-commit like my import reorderer, yapf, autopep8, etc.) have prior art.

Want to open an additional issue?

[Daenyth]

For dry-run to have a "show diff" variant? Sure

[seemethere]

@evhub Removed six dependency, switch to capsys

[coveralls]

Changes Unknown when pulling 04ebc77 on seemethere:dry_run into * on Yelp:master*.

[coveralls]

Changes Unknown when pulling 04ebc77 on seemethere:dry_run into * on Yelp:master*.

[coveralls]

Changes Unknown when pulling 04ebc77 on seemethere:dry_run into * on Yelp:master*.

[asottile]

We us this pattern in a lot of other repositories (could make this so you don't need monkeypatching):

def main(argv=None):
    parser = argparse.ArgumentParser()
    ...
    parser.pase_args(argv)

By default, argparse will go to sys.argv if the passed in argument is None otherwise it'll use the list of arguments.

This lets you call main(('-i', ..., ..., ...)) under test

[asottile]

Here's some prior art: https://github.com/asottile/reorder_python_imports/blob/b022734351abe44d0b05a71a4fa1175287c59b49/reorder_python_imports/main.py#L311-L341

[evhub]

I'm going to merge this and then try to address all of the issues brought up in this thread.