1 files changed, 168 insertions, 0 deletions
diff --git a/tools/lint/python/black.py b/tools/lint/python/black.py
new file mode 100644
index 0000000000..1e38dd669c
--- /dev/null
+++ b/tools/lint/python/black.py
@@ -0,0 +1,168 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import platform
+import re
+import signal
+import subprocess
+import sys
+
+import mozpack.path as mozpath
+from mozfile import which
+from mozlint import result
+from mozlint.pathutils import expand_exclusions
+
+here = os.path.abspath(os.path.dirname(__file__))
+BLACK_REQUIREMENTS_PATH = os.path.join(here, "black_requirements.txt")
+
+BLACK_INSTALL_ERROR = """
+Unable to install correct version of black
+Try to install it manually with:
+    $ pip install -U --require-hashes -r {}
+""".strip().format(
+    BLACK_REQUIREMENTS_PATH
+)
+
+
+def default_bindir():
+    # We use sys.prefix to find executables as that gets modified with
+    # virtualenv's activate_this.py, whereas sys.executable doesn't.
+    if platform.system() == "Windows":
+        return os.path.join(sys.prefix, "Scripts")
+    else:
+        return os.path.join(sys.prefix, "bin")
+
+
+def get_black_version(binary):
+    """
+    Returns found binary's version
+    """
+    try:
+        output = subprocess.check_output(
+            [binary, "--version"],
+            stderr=subprocess.STDOUT,
+            universal_newlines=True,
+        )
+    except subprocess.CalledProcessError as e:
+        output = e.output
+    try:
+        # Accept `black.EXE, version ...` on Windows.
+        # for old version of black, the output is
+        # black, version 21.4b2
+        # From black 21.11b1, the output is like
+        # black, 21.11b1 (compiled: no)
+        return re.match(r"black.*,( version)? (\S+)", output)[2]
+    except TypeError as e:
+        print("Could not parse the version '{}'".format(output))
+        print("Error: {}".format(e))
+
+
+def parse_issues(config, output, paths, *, log):
+    would_reformat = re.compile("^would reformat (.*)$", re.I)
+    reformatted = re.compile("^reformatted (.*)$", re.I)
+    cannot_reformat = re.compile("^error: cannot format (.*?): (.*)$", re.I)
+    results = []
+    for l in output.split(b"\n"):
+        line = l.decode("utf-8").rstrip("\r\n")
+        if line.startswith("All done!") or line.startswith("Oh no!"):
+            break
+
+        match = would_reformat.match(line)
+        if match:
+            res = {"path": match.group(1), "level": "error"}
+            results.append(result.from_config(config, **res))
+            continue
+
+        match = reformatted.match(line)
+        if match:
+            res = {"path": match.group(1), "level": "warning", "message": "reformatted"}
+            results.append(result.from_config(config, **res))
+            continue
+
+        match = cannot_reformat.match(line)
+        if match:
+            res = {"path": match.group(1), "level": "error", "message": match.group(2)}
+            results.append(result.from_config(config, **res))
+            continue
+
+        log.debug(f"Unhandled line: {line}")
+    return results
+
+
+def run_process(config, cmd):
+    orig = signal.signal(signal.SIGINT, signal.SIG_IGN)
+    proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+    signal.signal(signal.SIGINT, orig)
+    try:
+        output, _ = proc.communicate()
+        proc.wait()
+    except KeyboardInterrupt:
+        proc.kill()
+
+    return output
+
+
+def setup(root, **lintargs):
+    log = lintargs["log"]
+    virtualenv_bin_path = lintargs.get("virtualenv_bin_path")
+    # Using `which` searches multiple directories and handles `.exe` on Windows.
+    binary = which("black", path=(virtualenv_bin_path, default_bindir()))
+
+    if binary and os.path.exists(binary):
+        binary = mozpath.normsep(binary)
+        log.debug("Looking for black at {}".format(binary))
+        version = get_black_version(binary)
+        versions = [
+            line.split()[0].strip()
+            for line in open(BLACK_REQUIREMENTS_PATH).readlines()
+            if line.startswith("black==")
+        ]
+        if ["black=={}".format(version)] == versions:
+            log.debug("Black is present with expected version {}".format(version))
+            return 0
+        else:
+            log.debug("Black is present but unexpected version {}".format(version))
+
+    log.debug("Black needs to be installed or updated")
+    virtualenv_manager = lintargs["virtualenv_manager"]
+    try:
+        virtualenv_manager.install_pip_requirements(BLACK_REQUIREMENTS_PATH, quiet=True)
+    except subprocess.CalledProcessError:
+        print(BLACK_INSTALL_ERROR)
+        return 1
+
+
+def run_black(config, paths, fix=None, *, log, virtualenv_bin_path):
+    fixed = 0
+    binary = os.path.join(virtualenv_bin_path or default_bindir(), "black")
+
+    log.debug("Black version {}".format(get_black_version(binary)))
+
+    cmd_args = [binary]
+    if not fix:
+        cmd_args.append("--check")
+
+    base_command = cmd_args + paths
+    log.debug("Command: {}".format(" ".join(base_command)))
+    output = parse_issues(config, run_process(config, base_command), paths, log=log)
+
+    # black returns an issue for fixed files as well
+    for eachIssue in output:
+        if eachIssue.message == "reformatted":
+            fixed += 1
+
+    return {"results": output, "fixed": fixed}
+
+
+def lint(paths, config, fix=None, **lintargs):
+    files = list(expand_exclusions(paths, config, lintargs["root"]))
+
+    return run_black(
+        config,
+        files,
+        fix=fix,
+        log=lintargs["log"],
+        virtualenv_bin_path=lintargs.get("virtualenv_bin_path"),
+    )