Assert TempDirectory.path has not been cleaned up on access

src/pip/_internal/utils/temp_dir.py

@@ -54,12 +54,16 @@ class TempDirectory(object):
             path = self._create(kind)
 
         self._path = path
+        self._deleted = False
         self.delete = delete
         self.kind = kind
 
     @property
     def path(self):
         # type: () -> str
+        assert not self._deleted, (
+            "Attempted to access deleted path: {}".format(self._path)
+        )
         return self._path
 
     def __repr__(self):
@@ -88,8 +92,9 @@ class TempDirectory(object):
     def cleanup(self):
         """Remove the temporary directory created and reset state
         """
-        if os.path.exists(self.path):
-            rmtree(self.path)
+        self._deleted = True
+        if os.path.exists(self._path):
+            rmtree(self._path)
 
 
 class AdjacentTempDirectory(TempDirectory):

tests/unit/test_utils_temp_dir.py

@@ -55,7 +55,26 @@ def test_deletes_readonly_files():
         create_file(tmp_dir.path, "subfolder", "readonly-file")
         readonly_file(tmp_dir.path, "subfolder", "readonly-file")
 
-    assert not os.path.exists(tmp_dir.path)
+
+def test_path_access_after_context_raises():
+    with TempDirectory() as tmp_dir:
+        path = tmp_dir.path
+
+    with pytest.raises(AssertionError) as e:
+        _ = tmp_dir.path
+
+    assert path in str(e.value)
+
+
+def test_path_access_after_clean_raises():
+    tmp_dir = TempDirectory()
+    path = tmp_dir.path
+    tmp_dir.cleanup()
+
+    with pytest.raises(AssertionError) as e:
+        _ = tmp_dir.path
+
+    assert path in str(e.value)
 
 
 def test_create_and_cleanup_work():
@@ -66,7 +85,6 @@ def test_create_and_cleanup_work():
     assert os.path.exists(created_path)
 
     tmp_dir.cleanup()
-    assert tmp_dir.path is not None
     assert not os.path.exists(created_path)