fix: adjust OpsTest.tmp_path to avoid os.sep

pytest_operator/plugin.py

@@ -510,18 +510,30 @@ def models(self) -> Mapping[str, ModelState]:
         """Returns the dict of managed models by this fixture."""
         return {k: dataclasses.replace(v) for k, v in self._models.items()}
 
+    @staticmethod
+    def _model_name_to_filename(name: str):
+        """Sanitises a model name to one that is suitable for use as a component
+        of a filename."""
+        # Model names can only contain lowercase letters, digits, hyphens, and
+        # slashes, so most of the normalisation is already done, but we do a
+        # little bit of duplicated sanitisation here just to be certain.
+        # "letters" currently means ASCII letters, but may not in the future.
+        return "".join((c if c.isalnum() or c == "-" else "_") for c in name)
+
     @property
     def tmp_path(self) -> Path:
         tmp_path = self._global_tmp_path
         current_state = self.current_alias and self._models.get(self.current_alias)
         if current_state and current_state.tmp_path is None:
-            tmp_path = self._tmp_path_factory.mktemp(current_state.model_name)
+            tmp_path = self._tmp_path_factory.mktemp(
+                self._model_name_to_filename(current_state.model_name)
+            )
             current_state.tmp_path = tmp_path
         elif current_state and current_state.tmp_path:
             tmp_path = current_state.tmp_path
         elif not tmp_path:
             tmp_path = self._global_tmp_path = self._tmp_path_factory.mktemp(
-                self.default_model_name
+                self._model_name_to_filename(self.default_model_name)
             )
         log.info(f"Using tmp_path: {tmp_path}")
         return tmp_path

tests/integration/test_pytest_operator.py

@@ -115,6 +115,14 @@ def test_tmp_path(ops_test):
     assert ops_test.tmp_path.relative_to(tox_env_dir)
 
 
+async def test_tmp_path_nonpath_chars(ops_test):
+    model_alias = f"user{os.sep}name"
+    await ops_test.track_model(model_alias)
+    with ops_test.model_context(model_alias):
+        assert os.sep not in str(ops_test.tmp_path)
+        await ops_test.forget_model(model_alias)
+
+
 async def test_run(ops_test):
     assert await ops_test.run("/bin/true") == (0, "", "")
     assert await ops_test.run("/bin/false") == (1, "", "")

tests/unit/test_pytest_operator.py

@@ -60,6 +60,24 @@ async def test_without_tox(request, ops_test):
     result.assert_outcomes(passed=1)
 
 
+@patch.object(plugin.OpsTest, "default_model_name", "user/model")
+@patch.object(plugin.OpsTest, "_setup_model", AsyncMock())
+@patch.object(plugin.OpsTest, "_cleanup_models", AsyncMock())
+def test_tmp_path_with_nonpath_chars(pytester):
+    pytester.makepyfile(
+        f"""
+        import os
+        from pathlib import Path
+
+        os.environ.update(**{ENV})
+        async def test_with_tox(ops_test):
+            assert ops_test.tmp_path.name == "user_model0"
+        """
+    )
+    result = pytester.runpytest()
+    result.assert_outcomes(passed=1)
+
+
 async def test_destructive_mode(monkeypatch, tmp_path_factory):
     patch = monkeypatch.setattr
     patch(plugin.os, "getgroups", mock_getgroups := Mock(return_value=[]))