unittest-discover: Avoid adding test parent dir to sys.path.

When running tests from subfolders, import by "full dotted path" rather than just module name, removing the need to add the test parent folder to `sys.path`. This matches CPython more closely, which places `abspath(top)` at the start of `sys.path` but doesn't include the test file parent dir at all. It fixes issues where projects may include a `test_xxx.py` file in their distribution which would (prior to this change) be unintentionally found by unittest-discover. Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>

Author: andrewleech

python-stdlib/unittest-discover/manifest.py

@@ -1,4 +1,4 @@
-metadata(version="0.1.2")
+metadata(version="0.1.3")
 
 require("argparse")
 require("fnmatch")

python-stdlib/unittest-discover/tests/sub/sub.py

@@ -0,0 +1 @@
+imported=True

python-stdlib/unittest-discover/tests/sub/test_module_import.py

@@ -0,0 +1,13 @@
+importsys
+importunittest
+
+
+classTestModuleImport(unittest.TestCase):
+deftest_ModuleImportPath(self):
+try:
+fromsub.subimportimported
+assertimported
+exceptImportError:
+print("This test is intended to be run with unittest discover"
+"from the unittest-discover/tests dir. sys.path:", sys.path)
+raise

python-stdlib/unittest-discover/unittest/__main__.py

@@ -6,19 +6,24 @@
 fromfnmatchimportfnmatch
 frommicropythonimportconst
 
-fromunittestimportTestRunner, TestResult, TestSuite
+try:
+fromunittestimportTestRunner, TestResult, TestSuite
+exceptImportError:
+print("Error: This must be used from an installed copy of unittest-discover which will"
+" also install base unittest module.")
+raise
 
 
 # Run a single test in a clean environment.
 def_run_test_module(runner: TestRunner, module_name: str, *extra_paths: list[str]):
 module_snapshot= {k: vfork, vinsys.modules.items()}
 path_snapshot=sys.path[:]
 try:
-forpathinreversed(extra_paths):
+forpathinextra_paths:
 ifpath:
 sys.path.insert(0, path)
 
-module=__import__(module_name)
+module=__import__(module_name, None, None, module_name)
 suite=TestSuite(module_name)
 suite._load_module(module)
 returnrunner.run(suite)
@@ -36,16 +41,18 @@ def _run_all_in_dir(runner: TestRunner, path: str, pattern: str, top: str):
 forfname, ftype, *_inos.ilistdir(path):
 iffnamein ("..", "."):
 continue
+fpath="/".join((path, fname))
 ifftype==_DIR_TYPE:
 result+=_run_all_in_dir(
 runner=runner,
-path="/".join((path, fname)),
+path=fpath,
 pattern=pattern,
 top=top,
  )
 iffnmatch(fname, pattern):
-module_name=fname.rsplit(".", 1)[0]
-result+=_run_test_module(runner, module_name, path, top)
+module_path=fpath.rsplit(".", 1)[0] # remove ext
+module_path=module_path.replace("/", ".").strip(".")
+result+=_run_test_module(runner, module_path, top)
 returnresult