Add a test for the stderr supression

tests/test_torchfix.py

@@ -92,3 +92,32 @@ def test_errorcodes_distinct():
 
 def test_parse_error_code_str(case, expected):
     assert process_error_code_str(case) == expected
+
+
+def test_stderr_suppression(tmp_path):
+    data = "import torchvision.datasets as datasets\n"
+    data_path = tmp_path / "fixable.py"
+    data_path.write_text(data)
+    result = subprocess.run(
+        ["torchfix", "--select", "TOR203", "--fix", str(data_path)],
+        stderr=subprocess.PIPE,
+        text=True,
+    )
+    assert (
+        result.stderr
+        == "Finished checking 1 files.\nTransformed 1 files successfully.\n"
+    )
+
+    data = "import torchvision.datasets as datasets\n"
+    data_path = tmp_path / "fixable.py"
+    data_path.write_text(data)
+    result = subprocess.run(
+        ["torchfix", "--select", "TOR203", "--show-stderr", "--fix", str(data_path)],
+        stderr=subprocess.PIPE,
+        text=True,
+    )
+    assert (
+        result.stderr
+        == "Executing codemod...\nFailed to determine module name for {path}: '{path}' is not in the subpath of '' OR one path is relative and the other is absolute.\nFinished checking 1 files.\nTransformed 1 files successfully.\n"
+    )
+