Automatic color diffs for XCTest output

parse-xctest-output

#!/usr/bin/env python3

# A small script that parses the output of `swift test`
# and emits colored diffs for failed XCTAssertEquals.

import difflib
import fileinput
import re
import subprocess

# ANSI colors
BROWN = '\033[33m'
GREEN = '\033[92m'
RED = '\033[91m'
YELLOW = '\033[93m'
CLEAR = '\033[0m'

for line in fileinput.input():
    match = re.search(r'^(.+XCTAssertEqual failed:)\s+\("(.+)"\)\s+is not equal to\s+\("(.+)"\)', line)

    if match:
        [msg, a, b] = [match[1], match[2], match[3]]
        differ = difflib.SequenceMatcher(None, a, b)
        diff = ''

        for op, i1, i2, j1, j2 in differ.get_opcodes():
            if op == 'replace':
                diff += f'{YELLOW}{{{differ.a[i1:i2]} -> {differ.b[j1:j2]}}}{CLEAR}'
            elif op == 'equal':
                diff += differ.a[i1:i2]
            elif op == 'insert':
                diff += f'{GREEN}{{+ {differ.b[j1:j2]}}}{CLEAR}'
            elif op == 'delete':
                diff += f'{RED}{{- {differ.a[i1:i2]}}}{CLEAR}'

        print('\n'.join([
            f'{BROWN}{msg}{CLEAR}',
            diff,
            ''
        ]))