Method fail

tests/test-key-value-store.py:106–109

(self, name, expected, actual)

        print(f"  ✓ {name}")

    def fail(self, name, expected, actual):
        self.failed += 1
        self.errors.append((name, expected, actual))
        print(f"  ✗ {name}: expected {expected!r}, got {actual!r}")

    def error(self, name, exc):
        self.failed += 1