tests/util.py

   1 import os
   2 import unittest
   3 from contextlib import contextmanager
   4 from pathlib import Path
   5 from typing import List, Tuple, Iterator, Any
   6 import black
   7 from functools import partial
   8
   9 THIS_DIR = Path(__file__).parent
  10 PROJECT_ROOT = THIS_DIR.parent
  11 EMPTY_LINE = "# EMPTY LINE WITH WHITESPACE" + " (this comment will be removed)"
  12 DETERMINISTIC_HEADER = "[Deterministic header]"
  13
  14
  15 DEFAULT_MODE = black.Mode()
  16 ff = partial(black.format_file_in_place, mode=DEFAULT_MODE, fast=True)
  17 fs = partial(black.format_str, mode=DEFAULT_MODE)
  18
  19
  20 def dump_to_stderr(*output: str) -> str:
  21     return "\n" + "\n".join(output) + "\n"
  22
  23
  24 class BlackBaseTestCase(unittest.TestCase):
  25     maxDiff = None
  26     _diffThreshold = 2 ** 20
  27
  28     def assertFormatEqual(self, expected: str, actual: str) -> None:
  29         if actual != expected and not os.environ.get("SKIP_AST_PRINT"):
  30             bdv: black.DebugVisitor[Any]
  31             black.out("Expected tree:", fg="green")
  32             try:
  33                 exp_node = black.lib2to3_parse(expected)
  34                 bdv = black.DebugVisitor()
  35                 list(bdv.visit(exp_node))
  36             except Exception as ve:
  37                 black.err(str(ve))
  38             black.out("Actual tree:", fg="red")
  39             try:
  40                 exp_node = black.lib2to3_parse(actual)
  41                 bdv = black.DebugVisitor()
  42                 list(bdv.visit(exp_node))
  43             except Exception as ve:
  44                 black.err(str(ve))
  45         self.assertMultiLineEqual(expected, actual)
  46
  47
  48 @contextmanager
  49 def skip_if_exception(e: str) -> Iterator[None]:
  50     try:
  51         yield
  52     except Exception as exc:
  53         if exc.__class__.__name__ == e:
  54             unittest.skip(f"Encountered expected exception {exc}, skipping")
  55         else:
  56             raise
  57
  58
  59 def read_data(name: str, data: bool = True) -> Tuple[str, str]:
  60     """read_data('test_name') -> 'input', 'output'"""
  61     if not name.endswith((".py", ".pyi", ".out", ".diff")):
  62         name += ".py"
  63     base_dir = THIS_DIR / "data" if data else PROJECT_ROOT
  64     return read_data_from_file(base_dir / name)
  65
  66
  67 def read_data_from_file(file_name: Path) -> Tuple[str, str]:
  68     with open(file_name, "r", encoding="utf8") as test:
  69         lines = test.readlines()
  70     _input: List[str] = []
  71     _output: List[str] = []
  72     result = _input
  73     for line in lines:
  74         line = line.replace(EMPTY_LINE, "")
  75         if line.rstrip() == "# output":
  76             result = _output
  77             continue
  78
  79         result.append(line)
  80     if _input and not _output:
  81         # If there's no output marker, treat the entire file as already pre-formatted.
  82         _output = _input[:]
  83     return "".join(_input).strip() + "\n", "".join(_output).strip() + "\n"