Use correct input arg type for _bestrelpath (#9238)

Closes #8990

AUTHORS

@@ -139,6 +139,7 @@ Grigorii Eremeev (budulianin)
 Guido Wesdorp
 Guoqiang Zhang
 Harald Armin Massa
+Harshna
 Henk-Jaap Wagenaar
 Holger Kohr
 Hugo van Kemenade

changelog/8990.bugfix.rst

@@ -0,0 +1 @@
+Fix `pytest -vv` crashing with an internal exception `AttributeError: 'str' object has no attribute 'relative_to'` in some cases.

src/_pytest/pathlib.py

@@ -685,6 +685,8 @@ def bestrelpath(directory: Path, dest: Path) -> str:
 
     If no such path can be determined, returns dest.
     """
+    assert isinstance(directory, Path)
+    assert isinstance(dest, Path)
     if dest == directory:
         return os.curdir
     # Find the longest common directory.

src/_pytest/terminal.py

@@ -862,8 +862,10 @@ class TerminalReporter:
                     yellow=True,
                 )
 
-    def _locationline(self, nodeid, fspath, lineno, domain):
+    def _locationline(
-        def mkrel(nodeid):
+        self, nodeid: str, fspath: str, lineno: Optional[int], domain: str
+    ) -> str:
+        def mkrel(nodeid: str) -> str:
             line = self.config.cwd_relative_nodeid(nodeid)
             if domain and line.endswith(domain):
                 line = line[: -len(domain)]
@@ -873,13 +875,12 @@ class TerminalReporter:
             return line
 
         # collect_fspath comes from testid which has a "/"-normalized path.
-
         if fspath:
             res = mkrel(nodeid)
             if self.verbosity >= 2 and nodeid.split("::")[0] != fspath.replace(
                 "\\", nodes.SEP
             ):
-                res += " <- " + bestrelpath(self.startpath, fspath)
+                res += " <- " + bestrelpath(self.startpath, Path(fspath))
         else:
             res = "[location]"
         return res + " "