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How to Mock isort Output to Test Import Sorting in Python

Uses isort with check mode and a unittest mock to verify whether a Python source string has correctly sorted imports.

isort import-sorting mock
Python 
import isort
from unittest.mock import patch

code = """
import os
import sys
import json
import pathlib
"""

def check_imports_sorted(code_str):
    with patch("isort.api.output") as mock_output:
        isort.code(code_str, check=True, show_diff=True)
        return mock_output.called

if __name__ == "__main__":
   …
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