Support the load_tests protocol

[jruere]

The unittest module implements the load_tests protocol and this is not supported, AFAICT.

https://docs.python.org/2/library/unittest.html#load-tests-protocol

[CleanCut]

You are correct, I believe. I have never looked into that feature (in fact, I was barely aware that that feature existed).

It would be good to support the full unittest functionality. If you want to take a crack at submitting a patch, the place to tweak would probably be green/loader.py in loadFromModule() and/or loadFromModuleFilename().

If not, I may take a crack at it myself after some of the other enhancements.

[jayvdb]

Note that green is running the function collector and load_tests as test modules.

[CleanCut]

@jayvdb I cannot tell what what you are trying to say. load_tests is the function a user would define under the load_tests protocal (which is understandable so far). But I don't know what you mean by collector and I'm not sure what "running a function as a module" would mean, given that a module is a file containing Python definitions and statements.

Could you clarify what you mean?

[jayvdb]

Sorry. green is running the function load_tests if it exists. Here is a cut down example.

Create this file called test.py

import unittest

def load_tests(loader=unittest.loader.defaultTestLoader,
               tests=None, pattern=None):
    print('load_tests is run')
    try:
        tests = loader.loadTestsFromName('test.TestFoo')
        suite = unittest.TestSuite()
        suite.addTests(tests)
        return suite
    except Exception as e:
        print(e)
        raise

class TestFoo(unittest.TestCase):

    def test_foo(self):
        print('test_foo')

$ green test.py 
load_tests is run
load_tests is run
test_foo
Traceback (most recent call last):
  File "/usr/bin/green", line 9, in <module>
    load_entry_point('green==2.0.7', 'console_scripts', 'green')()
  File "/usr/lib/python2.7/site-packages/green/cmdline.py", line 75, in main
    result = run(test_suite, stream, args, testing)
  File "/usr/lib/python2.7/site-packages/green/runner.py", line 118, in run
    result.addProtoTestResult(proto_test_result)
  File "/usr/lib/python2.7/site-packages/green/result.py", line 337, in addProtoTestResult
    for test, err in proto_test_result.errors:
AttributeError: 'NoneType' object has no attribute 'errors'

[jayvdb]

Interesting... if load_tests returns None, TestFoo is not run.

import unittest

def load_tests(loader=unittest.loader.defaultTestLoader,
               tests=None, pattern=None):
     return None

class TestFoo(unittest.TestCase):

    def test_foo(self):
        print('test_foo')

$ green test.py 

Ran 0 tests in 0.124s

No Tests Found

[CleanCut]

Feature added by @althonos in #160

[CleanCut]

Included in just-released version 2.9.0.