Break out each check for better output granularity

changes/exceptions.py

@@ -0,0 +1,2 @@
+class ProbeException(Exception):
+    pass

changes/probe.py

@@ -4,49 +4,80 @@
 
 from plumbum.cmd import git
 
-from changes import attributes
+from changes import attributes, exceptions
 
 log = logging.getLogger(__name__)
 
 
-def probe_project(context):
-    """
-    Check if the project meets `changes` requirements
-    """
-    log.info('Checking project for changes requirements.')
-    # on [github](https://github.com)
-    git_remotes = git('remote', '-v').split('\n')
-    on_github = any(['github.com' in remote for remote in git_remotes])
-    log.info('On Github? %s', on_github)
-
-    # `setup.py`
-    setup = exists('setup.py')
-    log.info('setup.py? %s', setup)
-
-    # `requirements.txt`
-    has_requirements = exists(context.requirements)
-    if has_requirements:
-        # supports executing tests with `py.test`, `nosetests` or `tox`
-        requirements = io.open(context.requirements).read()
-        test_runners = ['pytest', 'nose', 'tox']
-        runs_tests = any([runner in requirements for runner in test_runners])
-        log.info('Runs tests? %s' % runs_tests)
-
-    # `CHANGELOG.md`
-    has_changelog = exists('CHANGELOG.md')
-    log.info('CHANGELOG.md? %s', has_changelog)
-
-    # `<module_name>/__init__.py` with `__version__` and `__url__`
+def report_and_raise(probe_name, probe_result, failure_msg):
+    """Logs the probe result and raises on failure"""
+    log.info('%s? %s' % (probe_name, probe_result))
+    if not probe_result:
+        raise exceptions.ProbeException(failure_msg)
+    else:
+        return True
+
+
+def on_github():
+    """on [github](https://github.com)"""
+    return report_and_raise(
+        'On GitHub',
+        any(['github.com' in remote for remote in git('remote', '-v').split('\n')]),
+        'Your package needs to be a GitHub project'
+    )
+
+
+def has_setup():
+    """`setup.py`"""
+    return report_and_raise('Has a setup.py', exists('setup.py'), 'Your project needs a setup.py')
+
+# supports executing tests with `py.test`, `nosetests` or `tox`
+TEST_RUNNERS = ['pytest', 'nose', 'tox']
+def has_requirements():
+    """`requirements.txt` and required requirements"""
+    has_requirements = report_and_raise('Has a requirements.txt', exists(context.requirements), 'Create a requirements.txt for your project')
+
+    requirements = io.open(context.requirements).read()
+    return report_and_raise(
+        'Has a test runner (%s)' % TEST_RUNNERS,
+        any([runner in requirements for runner in TEST_RUNNERS]),
+        'Please use one of the supported test runners (%s)' % TEST_RUNNERS
+    )
+
+
+def has_changelog():
+    """CHANGELOG.md"""
+    return report_and_raise('CHANGELOG.md', exists('CHANGELOG.md'), 'Create a CHANGELOG.md file')
+
+
+def has_readme():
+    """README.md"""
+    return report_and_raise('README.md', exists('README.md'), 'Create a README.md file')
+
+
+def has_metadata(context):
+    """`<module_name>/__init__.py` with `__version__` and `__url__`"""
     init_path = '%s/__init__.py' % context.module_name
     has_metadata = (
         exists(init_path) and
         attributes.has_attribute(context.module_name, '__version__') and
         attributes.has_attribute(context.module_name, '__url__')
     )
-    log.info('Has module metadata? %s', has_metadata)
+    return report_and_raise(
+        'Has module metadata',
+        has_metadata,
+        'Your %s/__init__.py must contain __version__ and __url__ attributes'
+    )
 
-    if not (on_github and setup and has_changelog and has_metadata and
-            has_requirements and runs_tests):
-        raise Exception('Project does not meet `changes` requirements')
-    else:
+
+def probe_project(context):
+    """
+    Check if the project meets `changes` requirements.
+    Complain and exit otherwise.
+    """
+    log.info('Checking project for changes requirements.')
+    if (on_github() and has_setup() and
+        has_readme() and has_changelog() and has_metadata(context) and
+        has_requirements):
         return True
+    return False