WIP: experiment with allow_escape for getlocation

src/_pytest/compat.py

@@ -100,15 +100,18 @@ class CodeLocation(NamedTuple):
     lineno: int
 
 
+# TODO: integrate after pytest 3.6.0 has been dropped
 def CodeLocation__str__(self: CodeLocation) -> str:
-    """Python 3.6 hack for NamedTuple __str__"""
+    """Python 3.6.0 hack for NamedTuple __str__"""
     return f"{self.path}:{self.lineno}"
 
 
 setattr(CodeLocation, "__str__", CodeLocation__str__)
 
 
-def getlocation(function, curdir: Path | None) -> CodeLocation:
+def getlocation(
+    function, *, relative_to: Path | None, allow_escape: bool
+) -> CodeLocation:
     function = get_real_func(function)
     fn = Path(inspect.getfile(function))
     lineno = function.__code__.co_firstlineno
@@ -116,9 +119,12 @@ def getlocation(function, curdir: Path | None) -> CodeLocation:
     # TODO: this cycle indicates a larger issue
     from .pathlib import bestrelpath
 
-    if curdir is not None:
+    if relative_to is not None:
         try:
-            relfn = Path(bestrelpath(curdir, fn))
+            if allow_escape:
+                relfn = Path(bestrelpath(relative_to, fn))
+            else:
+                relfn = relative_to.relative_to(relative_to)
         except ValueError:
             pass
         else:

src/_pytest/fixtures.py

@@ -660,7 +660,11 @@ class FixtureRequest:
                     "\n\nRequested here:\n{}:{}".format(
                         funcitem.nodeid,
                         fixturedef.argname,
-                        getlocation(fixturedef.func, funcitem.config.rootpath),
+                        getlocation(
+                            fixturedef.func,
+                            relative_to=funcitem.config.rootpath,
+                            allow_escape=True,
+                        ),
                         source_path_str,
                         source_lineno,
                     )
@@ -1210,7 +1214,7 @@ class FixtureFunctionMarker:
 
         name = self.name or function.__name__
         if name == "request":
-            location = getlocation(function, None)
+            location = getlocation(function, relative_to=None, allow_escape=True)
             fail(
                 "'request' is a reserved word for fixtures, use another name:\n  {}".format(
                     location

src/_pytest/python.py

@@ -1576,9 +1576,8 @@ def _show_fixtures_per_test(config: Config, session: Session) -> None:
     tw = _pytest.config.create_terminal_writer(config)
     verbose = config.getvalue("verbose")
 
-    def get_best_relpath(func) -> str:
-        loc = getlocation(func, str(curdir))
-        return bestrelpath(curdir, Path(loc))
+    def get_best_relpath(func):
+        return getlocation(func, curdir)
 
     def write_fixture(fixture_def: fixtures.FixtureDef[object]) -> None:
         argname = fixture_def.argname
@@ -1599,9 +1598,12 @@ def _show_fixtures_per_test(config: Config, session: Session) -> None:
     def write_item(item: nodes.Item) -> None:
         # Not all items have _fixtureinfo attribute.
         info: Optional[FuncFixtureInfo] = getattr(item, "_fixtureinfo", None)
+        function: Optional[Callable[..., Any]] = getattr(item, "function", None)
         if info is None or not info.name2fixturedefs:
             # This test item does not use any fixtures.
             return
+        if function is None:
+            return
         tw.line()
         tw.sep("-", f"fixtures used by {item.name}")
         # TODO: Fix this type ignore.
@@ -1642,7 +1644,7 @@ def _showfixtures_main(config: Config, session: Session) -> None:
         if not fixturedefs:
             continue
         for fixturedef in fixturedefs:
-            loc = getlocation(fixturedef.func, curdir)
+            loc = getlocation(fixturedef.func, relative_to=curdir, allow_escape=True)
             if (fixturedef.argname, loc) in seen:
                 continue
             seen.add((fixturedef.argname, loc))
@@ -1668,7 +1670,7 @@ def _showfixtures_main(config: Config, session: Session) -> None:
             continue
         tw.write(f"{argname}", green=True)
         if fixturedef.scope != "function":
-            tw.write(" [%s scope]" % fixturedef.scope, cyan=True)
+            tw.write(f" [{fixturedef.scope} scope]", cyan=True)
         tw.write(f" -- {prettypath}", yellow=True)
         tw.write("\n")
         doc = inspect.getdoc(fixturedef.func)