from typing import List, Tuple from black.trans import iter_fexpr_spans def test_fexpr_spans() -> None: def check( string: str, expected_spans: List[Tuple[int, int]], expected_slices: List[str] ) -> None: spans = list(iter_fexpr_spans(string)) # Checking slices isn't strictly necessary, but it's easier to verify at # a glance than only spans assert len(spans) == len(expected_slices) for (i, j), slice in zip(spans, expected_slices): assert 0 <= i <= j <= len(string) assert string[i:j] == slice assert spans == expected_spans # Most of these test cases omit the leading 'f' and leading / closing quotes # for convenience # Some additional property-based tests can be found in # https://github.com/psf/black/pull/2654#issuecomment-981411748 check("""{var}""", [(0, 5)], ["{var}"]) check("""f'{var}'""", [(2, 7)], ["{var}"]) check("""f'{1 + f() + 2 + "asdf"}'""", [(2, 24)], ["""{1 + f() + 2 + "asdf"}"""]) check("""text {var} text""", [(5, 10)], ["{var}"]) check("""text {{ {var} }} text""", [(8, 13)], ["{var}"]) check("""{a} {b} {c}""", [(0, 3), (4, 7), (8, 11)], ["{a}", "{b}", "{c}"]) check("""f'{a} {b} {c}'""", [(2, 5), (6, 9), (10, 13)], ["{a}", "{b}", "{c}"]) check("""{ {} }""", [(0, 6)], ["{ {} }"]) check("""{ {{}} }""", [(0, 8)], ["{ {{}} }"]) check("""{ {{{}}} }""", [(0, 10)], ["{ {{{}}} }"]) check("""{{ {{{}}} }}""", [(5, 7)], ["{}"]) check("""{{ {{{var}}} }}""", [(5, 10)], ["{var}"]) check("""{f"{0}"}""", [(0, 8)], ["""{f"{0}"}"""]) check("""{"'"}""", [(0, 5)], ["""{"'"}"""]) check("""{"{"}""", [(0, 5)], ["""{"{"}"""]) check("""{"}"}""", [(0, 5)], ["""{"}"}"""]) check("""{"{{"}""", [(0, 6)], ["""{"{{"}"""]) check("""{''' '''}""", [(0, 9)], ["""{''' '''}"""]) check("""{'''{'''}""", [(0, 9)], ["""{'''{'''}"""]) check("""{''' {'{ '''}""", [(0, 13)], ["""{''' {'{ '''}"""]) check( '''f\'\'\'-{f"""*{f"+{f'.{x}.'}+"}*"""}-'y\\'\'\'\'''', [(5, 33)], ['''{f"""*{f"+{f'.{x}.'}+"}*"""}'''], ) check(r"""{}{""", [(0, 2)], ["{}"]) check("""f"{'{'''''''''}\"""", [(2, 15)], ["{'{'''''''''}"])