def METHOD_NAME(self, source_dir):
    tests = []
    for test_dir in source_dir.iterdir():
        if not test_dir.is_dir():
            continue
        plan_candidates = [
            test_dir / "left.plan.json",
            test_dir / "left.plan.yaml",
            test_dir / "left.plan.yml",
        ]
        for c in plan_candidates:
            if not c.exists():
                continue
            tests.append(self.load_plan(test_dir, c))
    return tests