config: improve typing

src/_pytest/_code/__init__.py

@@ -6,6 +6,7 @@ from .code import Frame
 from .code import getfslineno
 from .code import getrawcode
 from .code import Traceback
+from .code import TracebackEntry
 from .source import compile_ as compile
 from .source import Source
 
@@ -17,6 +18,7 @@ __all__ = [
     "getfslineno",
     "getrawcode",
     "Traceback",
+    "TracebackEntry",
     "compile",
     "Source",
 ]

src/_pytest/_code/code.py

@@ -213,7 +213,7 @@ class TracebackEntry:
         return source.getstatement(self.lineno)
 
     @property
-    def path(self):
+    def path(self) -> Union[py.path.local, str]:
         """ path to the source code """
         return self.frame.code.path