Use importlib also for prepend and append import modes

Author: nicoddemus

src/_pytest/_code/code.py

@@ -1199,7 +1199,10 @@ def getfslineno(obj: Any) -> Tuple[Union[str, py.path.local], int]:
 
 
 def filter_traceback(entry: TracebackEntry) -> bool:
-    """Return True if a TracebackEntry instance should be removed from tracebacks:
+    """Return True if a TracebackEntry instance should be included in tracebacks.
+
+    We hide traceback entries of:
+
     * dynamically generated code (no code to show up for it);
     * internal traceback from pytest or its internal libraries, py and pluggy.
     """

src/_pytest/config/__init__.py

@@ -98,6 +98,15 @@ def __str__(self):
         )
 
 
+def filter_traceback_for_conftest_import_failure(entry) -> bool:
+    """filters tracebacks entries which point to pytest internals or importlib.
+
+    Make a special case for importlib because we use it to import test modules and conftest files
+    in _pytest.pathlib.import_path.
+    """
+    return filter_traceback(entry) and "importlib" not in str(entry.path).split(os.sep)
+
+
 def main(args=None, plugins=None) -> Union[int, ExitCode]:
     """ return exit code, after performing an in-process test run.
 
@@ -115,7 +124,9 @@ def main(args=None, plugins=None) -> Union[int, ExitCode]:
             tw.line(
                 "ImportError while loading conftest '{e.path}'.".format(e=e), red=True
             )
-            exc_info.traceback = exc_info.traceback.filter(filter_traceback)
+            exc_info.traceback = exc_info.traceback.filter(
+                filter_traceback_for_conftest_import_failure
+            )
             exc_repr = (
                 exc_info.getrepr(style="short", chain=False)
                 if exc_info.traceback

src/_pytest/pathlib.py

@@ -1,5 +1,6 @@
 import atexit
 import fnmatch
+import importlib.util
 import itertools
 import os
 import shutil
@@ -463,8 +464,6 @@ def import_path(
         raise ImportError(path)
 
     if mode == ImportMode.importlib:
-        import importlib.util
-
         module_name = path.stem
 
         for meta_importer in sys.meta_path:
@@ -504,7 +503,7 @@ def import_path(
         if str(pkg_root) != sys.path[0]:
             sys.path.insert(0, str(pkg_root))
 
-    __import__(module_name)
+    importlib.import_module(module_name)
 
     mod = sys.modules[module_name]
     if path.name == "__init__.py":