lint: Generalize --skip arg and move logic to zulint/command.

tools/lint

@@ -90,15 +90,11 @@ def run():
     linter_config.external_linter('templates', ['tools/check-templates'], ['handlebars', 'html'])
     linter_config.external_linter('swagger', ['node', 'tools/check-swagger'], ['yaml'])
     linter_config.external_linter('shellcheck', ['shellcheck', '-x'], ['sh'])
-    if 'mypy' not in args.skip:
-        command = ['tools/run-mypy']
-        if args.force:
-            command.append('--force')
-        linter_config.external_linter('mypy', command, ['py'], pass_targets=False)
-
-    # Disabled check for imperative mood until it is stabilized
-    if 'gitlint' not in args.skip:
-        linter_config.external_linter('gitlint', ['tools/commit-message-lint'])
+    command = ['tools/run-mypy']
+    if args.force:
+        command.append('--force')
+    linter_config.external_linter('mypy', command, ['py'], pass_targets=False)
+    linter_config.external_linter('gitlint', ['tools/commit-message-lint'])
 
     @linter_config.lint
     def custom_py():
@@ -135,7 +131,7 @@ def run():
         failed = check_pep8(list(python_part2))
         return 1 if failed else 0
 
-    linter_config.do_lint(only=args.only)
+    linter_config.do_lint(skip=args.skip, only=args.only)
 
 if __name__ == '__main__':
     run()

tools/zulint/command.py

@@ -111,10 +111,13 @@ class LinterConfig:
 
         self.lint_functions[name] = run_linter
 
-    def do_lint(self, only=[]):
-        # type: (List[str]) -> None
+    def do_lint(self, only=[], skip=[]):
+        # type: (List[str], List[str]) -> None
+        assert not only or not skip, "Only one of --only or --skip can be used at once."
         if only:
             self.lint_functions = {linter: self.lint_functions[linter] for linter in only}
+        for linter in skip:
+            del self.lint_functions[linter]
 
         failed = run_parallel(self.lint_functions)
         sys.exit(1 if failed else 0)