Use importlib to avoid module name clashes for pytest

CHANGELOG

@@ -1,3 +1,9 @@
+(unreleased)
+============
+
+- add ``"importlib"`` pyimport mode for python3.5+, allowing unimportable test suites
+  to contain identically named modules.
+
 1.7.0 (2018-10-11)
 ==================
 

py/_path/local.py

@@ -18,6 +18,11 @@ def map_as_list(func, iter):
 else:
     map_as_list = map
 
+ALLOW_IMPORTLIB_MODE = sys.version_info > (3,5)
+if ALLOW_IMPORTLIB_MODE:
+    import importlib
+
+
 class Stat(object):
     def __getattr__(self, name):
         return getattr(self._osstatresult, "st_" + name)
@@ -647,10 +652,35 @@ def pyimport(self, modname=None, ensuresyspath=True):
         If ensuresyspath=="append" the root dir will be appended
         if it isn't already contained in sys.path.
         if ensuresyspath is False no modification of syspath happens.
+
+        Special value of ensuresyspath=="importlib" is intended
+        purely for using in pytest, it is capable only of importing
+        separate .py files outside packages, e.g. for test suite
+        without any __init__.py file. It effectively allows having
+        same-named test modules in different places and offers
+        mild opt-in via this option. Note that it works only in
+        recent versions of python.
         """
         if not self.check():
             raise py.error.ENOENT(self)
 
+        if ensuresyspath == 'importlib':
+            if modname is None:
+                modname = self.purebasename
+            if not ALLOW_IMPORTLIB_MODE:
+                raise ImportError(
+                    "Can't use importlib due to old version of Python")
+            spec = importlib.util.spec_from_file_location(
+                modname, str(self))
+            if spec is None:
+                raise ImportError(
+                    "Can't find module %s at location %s" %
+                    (modname, str(self))
+                )
+            mod = importlib.util.module_from_spec(spec)
+            spec.loader.exec_module(mod)
+            return mod
+
         pkgpath = None
         if modname is None:
             pkgpath = self.pypkgpath()

testing/path/test_local.py

@@ -581,6 +581,39 @@ def test_ensuresyspath_append(self, tmpdir):
         assert str(root1) not in sys.path[:-1]
 
 
+class TestImportlibImport:
+    pytestmark = py.test.mark.skipif("sys.version_info < (3, 5)")
+
+    OPTS = {'ensuresyspath': 'importlib'}
+
+    def test_pyimport(self, path1):
+        obj = path1.join('execfile.py').pyimport(**self.OPTS)
+        assert obj.x == 42
+        assert obj.__name__ == 'execfile'
+
+    def test_pyimport_dir_fails(self, tmpdir):
+        p = tmpdir.join("hello_123")
+        p.ensure("__init__.py")
+        with pytest.raises(ImportError):
+            p.pyimport(**self.OPTS)
+
+    def test_pyimport_execfile_different_name(self, path1):
+        obj = path1.join('execfile.py').pyimport(modname="0x.y.z", **self.OPTS)
+        assert obj.x == 42
+        assert obj.__name__ == '0x.y.z'
+
+    def test_pyimport_relative_import_fails(self, path1):
+        otherdir = path1.join('otherdir')
+        with pytest.raises(ImportError):
+            otherdir.join('a.py').pyimport(**self.OPTS)
+
+    def test_pyimport_doesnt_use_sys_modules(self, tmpdir):
+        p = tmpdir.ensure('file738jsk.py')
+        mod = p.pyimport(**self.OPTS)
+        assert mod.__name__ == 'file738jsk'
+        assert 'file738jsk' not in sys.modules
+
+
 def test_pypkgdir(tmpdir):
     pkg = tmpdir.ensure('pkg1', dir=1)
     pkg.ensure("__init__.py")