Remove --color from ESLint output when running in presubmit

Fixed: 862792
Change-Id: I250e91a1db5f8df71fff33c17c7a04a9fd6c8739
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1937584
Commit-Queue: Dan Beam <dbeam@chromium.org>
Auto-Submit: Dan Beam <dbeam@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719450}

PRESUBMIT_test_mocks.py

@@ -71,6 +71,7 @@ class MockInputApi(object):
     self.python_executable = sys.executable
     self.platform = sys.platform
     self.subprocess = subprocess
+    self.sys = sys
     self.files = []
     self.is_committing = False
     self.change = MockChange([])

tools/web_dev_style/js_checker.py

@@ -68,7 +68,9 @@ class JSChecker(object):
     for f in affected_js_files:
       affected_js_files_paths.append(f.AbsoluteLocalPath())
 
-    args = ["--color", "--format", format, "--ignore-pattern '!.eslintrc.js'"]
+    from os import isatty as os_isatty
+    args = ["--color"] if os_isatty(self.input_api.sys.stdout.fileno()) else []
+    args += ["--format", format, "--ignore-pattern '!.eslintrc.js'"]
     args += affected_js_files_paths
 
     import eslint

tools/web_dev_style/js_checker_eslint_test.py

@@ -44,11 +44,11 @@ class JsCheckerEsLintTest(unittest.TestCase):
     self.assertEqual(line, message.get('line'))
 
   def testGetElementByIdCheck(self):
-    results_json = self._runChecks('var a = document.getElementById(\'foo\');')
+    results_json = self._runChecks("const a = document.getElementById('foo');")
     self._assertError(results_json, 'no-restricted-properties', 1)
 
   def testPrimitiveWrappersCheck(self):
-    results_json = self._runChecks('var a = new Number(1);')
+    results_json = self._runChecks('const a = new Number(1);')
     self._assertError(results_json, 'no-new-wrappers', 1)