def test_collection_args_do_not_duplicate_modules(pytester: Pytester) -> None:
    """Test that when multiple collection args are specified on the command line
    for the same module, only a single Module collector is created.

    Regression test for #723, #3358.
    """
    pytester.makepyfile(
        **{
            "d/test_it": """
                def test_1(): pass
                def test_2(): pass
                """
        }
    )

    result = pytester.runpytest(
        "--collect-only",
        "d/test_it.py::test_1",
        "d/test_it.py::test_2",
    )
    result.stdout.fnmatch_lines(
        [
            "  <Dir d>",
            "    <Module test_it.py>",
            "      <Function test_1>",
            "      <Function test_2>",
        ],
        consecutive=True,
    )

    # Different, but related case.
    result = pytester.runpytest(
        "--collect-only",
        "--keep-duplicates",
        "d",
        "d",
    )
    result.stdout.fnmatch_lines(
        [
            "  <Dir d>",
            "    <Module test_it.py>",
            "      <Function test_1>",
            "      <Function test_2>",
            "      <Function test_1>",
            "      <Function test_2>",
        ],
        consecutive=True,
    )
Test that when multiple collection args are specified on the command line
    for the same module, only a single Module collector is created.

    Regression test for #723, #3358.
    
testing/test_session.py