Bug 1608535 - [lint] Forward new --no-error-on-unmatched-pattern to eslint, r=Standard8

This prevents eslint from dumping an error and bailing when a path was specified that
doesn't contain any lintable files.

This patch fixes a bad interaction with 'mozlint' where passing a directory containing
failures alongside a directory that doesn't have lintable files results in the errors
being hidden and mozlint reporting that everying is OK.

Differential Revision: https://phabricator.services.mozilla.com/D60686

--HG--
extra : moz-landing-system : lando

tools/lint/eslint/__init__.py

@@ -8,7 +8,6 @@ from __future__ import absolute_import, print_function
 
 import json
 import os
-import re
 import signal
 import sys
 
@@ -75,6 +74,7 @@ def lint(paths, config, binary=None, fix=None, setup=None, **lintargs):
                 # This keeps ext as a single argument.
                 '--ext', '[{}]'.format(','.join(config['extensions'])),
                 '--format', 'json',
+                '--no-error-on-unmatched-pattern',
                 ] + extra_args + exclude_args + paths
     log.debug("Command: {}".format(' '.join(cmd_args)))
 
@@ -106,10 +106,6 @@ def lint(paths, config, binary=None, fix=None, setup=None, **lintargs):
         jsonresult = json.loads(proc.output[0])
     except ValueError:
         output = "\n".join(proc.output)
-        if re.search(r'No files matching the pattern "(.*)" were found.', output):
-            print("warning: no files to lint (eslint)")
-            return []
-
         print(ESLINT_ERROR_MESSAGE.format(output))
         return 1
 

tools/lint/test/test_eslint.py

@@ -12,8 +12,13 @@ def test_lint_with_global_exclude(lint, config, paths):
 
 
 def test_no_files_to_lint(lint, config, paths):
-    ret = lint(paths('nolint'), root=build.topsrcdir)
-    assert ret == []
+    # A directory with no files to lint.
+    results = lint(paths('nolint'), root=build.topsrcdir)
+    assert results == []
+
+    # Errors still show up even when a directory with no files is passed in.
+    results = lint(paths('nolint', 'subdir/bad.js'), root=build.topsrcdir)
+    assert len(results) == 1
 
 
 if __name__ == '__main__':