def METHOD_NAME():
    """Determines how often each test file is run per platform and floatX setting.
    An exception is raised if tests run multiple times with the same configuration.
    """
    # First collect the matrix definitions from testing workflows
    matrices = {}
    for wf in ["tests.yml"]:
        wfname = wf.rstrip(".yml")
        wfdef = yaml.safe_load(open(Path(".github", "workflows", wf)))
        for jobname, jobdef in wfdef["jobs"].items():
            matrix = jobdef.get("strategy", {}).get("matrix", {})
            if matrix:
                matrices[(wfname, jobname)] = matrix
            else:
                _log.warning("No matrix in %s/%s", wf, jobname)
    # Now create an empty DataFrame to count based on OS/floatX/testfile
    all_os = []
    all_floatX = []
    for matrix in matrices.values():
        all_os += matrix["os"]
        all_floatX += matrix["floatx"]
    all_os = tuple(sorted(set(all_os)))
    all_floatX = tuple(sorted(set(all_floatX)))
    all_tests = find_testfiles()
    df = pandas.DataFrame(
        columns=pandas.MultiIndex.from_product(
            [sorted(all_floatX), sorted(all_os)], names=["floatX", "os"]
        ),
        index=pandas.Index(sorted(all_tests), name="testfile"),
    )
    df.loc[:, :] = 0
    # Count how often the testfiles are included in job definitions
    for matrix in matrices.values():
        for os_, floatX, subset in itertools.product(
            matrix["os"], matrix["floatx"], matrix["test-subset"]
        ):
            lines = [l for l in subset.split("\n") if l]
            if "windows" in os_:
                # Windows jobs need \ in line breaks within the test-subset!
                # The following checks that these trailing \ are present in
                # all items except the last.
                if lines and lines[-1].endswith(" \\"):
                    raise Exception(
                        f"Last entry '{line}' in Windows test subset should end WITHOUT ' \\'."
                    )
                for line in lines[:-1]:
                    if not line.endswith(" \\"):
                        raise Exception(f"Missing ' \\' after '{line}' in Windows test-subset.")
                lines = [line.rstrip(" \\") for line in lines]
            # Unpack lines with >1 item
            testfiles = []
            for line in lines:
                testfiles += line.split(" ")
            ignored = {item[8:].lstrip(" =") for item in testfiles if item.startswith("--ignore")}
            included = {item for item in testfiles if item and not item.startswith("--ignore")}
            if ignored and not included:
                # if no testfile is specified explicitly pytest runs all except the ignored ones
                included = all_tests - ignored
            for testfile in included:
                df.loc[testfile, (floatX, os_)] += 1
    ignored_by_all = set(df[df.eq(0).all(axis=1)].index)
    run_multiple_times = set(df[df.gt(1).any(axis=1)].index)
    # Print summary, warnings and raise errors on unwanted configurations
    _log.info("Number of test runs (❌=0, ✅=once)\n%s", df.replace(0, "❌").replace(1, "✅"))
    if ignored_by_all:
        raise AssertionError(
            f"{len(ignored_by_all)} tests are completely ignored:\n{ignored_by_all}"
        )
    if run_multiple_times:
        raise AssertionError(
            f"{len(run_multiple_times)} tests are run multiple times with the same OS and floatX setting:\n{run_multiple_times}"
        )
    return