DevTools: Add lint_javascript.py to drive eslint

third_party/WebKit/Source/devtools/scripts/lint_javascript.py

Index: third_party/WebKit/Source/devtools/scripts/lint_javascript.py
diff --git a/third_party/WebKit/Source/devtools/scripts/lint_javascript.py b/third_party/WebKit/Source/devtools/scripts/lint_javascript.py
new file mode 100755
index 0000000000000000000000000000000000000000..a7006223e29da36183d94bd8fbcc816459a02f74
--- /dev/null
+++ b/third_party/WebKit/Source/devtools/scripts/lint_javascript.py
@@ -0,0 +1,111 @@
+#!/usr/bin/env python
+#
+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+import os.path as path
+import re
+import subprocess
+import sys
+
+files_to_lint = None
+
+if len(sys.argv) == 2:
+    if sys.argv[1] == "--help":
+        print("Usage: %s [file|dir|glob]*" % path.basename(sys.argv[0]))
+        print
+        print(" [file|dir|glob]*  Path or glob to run eslint on.")
+        print("                   If absent, the entire frontend will be checked.")
+        sys.exit(0)
+
+    else:
+        print "Linting only this path:\n %s" % sys.argv[1:]
+        files_to_lint = sys.argv[1:]
+
+
+is_cygwin = sys.platform == "cygwin"
+
+
+def popen(arguments):
+    return subprocess.Popen(arguments, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+
+
+def to_platform_path(filepath):
+    if not is_cygwin:
+        return filepath
+    return re.sub(r"^/cygdrive/(\w)", "\\1:", filepath)
+
+
+def to_platform_path_exact(filepath):
+    if not is_cygwin:
+        return filepath
+    output, _ = popen(["cygpath", "-w", filepath]).communicate()
+    # pylint: disable=E1103
+    return output.strip().replace("\\", "\\\\")
+
+scripts_path = path.dirname(path.abspath(__file__))
+devtools_path = path.dirname(scripts_path)
+devtools_frontend_path = path.join(devtools_path, "front_end")
+
+
+# Based on http://stackoverflow.com/questions/377017/test-if-executable-exists-in-python.
+def which(program):
+    def is_exe(fpath):
+        return path.isfile(fpath) and os.access(fpath, os.X_OK)
+
+    fpath, fname = path.split(program)
+    if fpath:
+        if is_exe(program):
+            return program
+    else:
+        for part in os.environ["PATH"].split(os.pathsep):
+            part = part.strip("\"")
+            exe_file = path.join(part, program)
+            if is_exe(exe_file):
+                return exe_file
+    return None
+
+
+print "Linting JavaScript with eslint...\n"
+
+
+def js_lint(files_list=None):
+    errors_found = False
+
+    eslint_path = which("eslint")
+    if not eslint_path:
+        print "!! Skipping JavaScript linting because eslint is not installed."
+        print "!!   npm install -g eslint"
+        errors_found = False  # Linting is opt-in for now, so this is a soft failure
+        return errors_found
+
+    if files_list is None:
+        files_list = [devtools_frontend_path]
+
+    eslintconfig_path = path.join(devtools_path, "front_end/.eslintrc.js")
+    eslintignore_path = path.join(devtools_path, "front_end/.eslintignore")
+    exec_command = [
+        eslint_path,
+        "--config", to_platform_path_exact(eslintconfig_path),
+        "--ignore-path", to_platform_path_exact(eslintignore_path),
+        " ".join(files_list)
+        ]
+
+    eslint_proc = popen(exec_command)
+    (eslint_proc_out, _) = eslint_proc.communicate()
+    if eslint_proc.returncode != 0:
+        errors_found = True
+    else:
+        print "eslint exited successfully"
+
+    print eslint_proc_out
+
+    if errors_found:

[caseq, 2016/04/26 03:47:18]

nit: I'd leave this one on the top level, I just thought we want the
errors_found to be declared within js_lint() so that references within the
function use local var, not one from closure.

[paulirish, 2016/04/26 16:50:51]

groovy. done.

+        print "ERRORS DETECTED"
+        sys.exit(1)
+    else:
+        print "OK"
+
+js_lint(files_to_lint)