Look for ini file to spot python project root (#755)

* Look for ini file to spot project root

When looking for the project root folder it would be better
to check for some well-known init file instead of __init__.py.
Indeed, with python3 it is now possible to have namespace modules
where intermediate dirs are not required to include the __init__.py file.

* Break if statement conditions over several lines

* Add blank lines for the if block

* Add test for FindProjectRoot

* Typo: missing / for MANIFEST.in

* Fix test for non-namespace package

* Add more test cases

test/command_callback/python_paths/namespace_package_manifest/MANIFEST.in

@@ -0,0 +1,3 @@
+include README.md
+include *.ini *.cfg *.txt
+include requirements/*.txt

test/command_callback/python_paths/namespace_package_pytest/pytest.ini

@@ -0,0 +1,2 @@
+[pytest]
+DJANGO_SETTINGS_MODULE=foo.settings

test/command_callback/python_paths/namespace_package_setup/setup.cfg

@@ -0,0 +1,2 @@
+[flake8]
+max-line-length = 119

test/command_callback/python_paths/namespace_package_tox/tox.ini

@@ -0,0 +1,3 @@
+[tox]
+envlist =
+  py352

test/command_callback/test_flake8_command_callback.vader

@@ -65,6 +65,41 @@ Execute(The flake8 callbacks should detect virtualenv directories):
   \   . ' --stdin-display-name %s -',
   \ ale_linters#python#flake8#GetCommand(bufnr(''), ['3.0.0'])
 
+Execute(The FindProjectRoot should detect the project root directory for namespace package via Manifest.in):
+  silent execute 'file ' . fnameescape(g:dir . '/python_paths/namespace_package_manifest/namespace/foo/bar.py')
+
+  AssertEqual
+  \ fnameescape(g:dir . '/python_paths/namespace_package_manifest'),
+  \ ale#python#FindProjectRoot(bufnr(''))
+
+Execute(The FindProjectRoot should detect the project root directory for namespace package via setup.cf):
+  silent execute 'file ' . fnameescape(g:dir . '/python_paths/namespace_package_setup/namespace/foo/bar.py')
+
+  AssertEqual
+  \ fnameescape(g:dir . '/python_paths/namespace_package_setup'),
+  \ ale#python#FindProjectRoot(bufnr(''))
+
+Execute(The FindProjectRoot should detect the project root directory for namespace package via pytest.ini):
+  silent execute 'file ' . fnameescape(g:dir . '/python_paths/namespace_package_pytest/namespace/foo/bar.py')
+
+  AssertEqual
+  \ fnameescape(g:dir . '/python_paths/namespace_package_pytest'),
+  \ ale#python#FindProjectRoot(bufnr(''))
+
+Execute(The FindProjectRoot should detect the project root directory for namespace package via tox.ini):
+  silent execute 'file ' . fnameescape(g:dir . '/python_paths/namespace_package_tox/namespace/foo/bar.py')
+
+  AssertEqual
+  \ fnameescape(g:dir . '/python_paths/namespace_package_tox'),
+  \ ale#python#FindProjectRoot(bufnr(''))
+
+Execute(The FindProjectRoot should detect the project root directory for non-namespace package):
+  silent execute 'file ' . fnameescape(g:dir . '/python_paths/no_virtualenv/subdir/foo/bar.py')
+
+  AssertEqual
+  \ fnameescape(g:dir . '/python_paths/no_virtualenv/subdir'),
+  \ ale#python#FindProjectRoot(bufnr(''))
+
 " Some users currently run flake8 this way, so we should support it.
 Execute(Using `python -m flake8` should be supported for running flake8):
   silent execute 'file ' . fnameescape(g:dir . '/python_paths/with_virtualenv/subdir/foo/bar.py')