feat: add respect to @noflow annotation (#451)

* fix: general filter for all rules - should be either @flow file, or `onlyFilesWithFlowAnnotation` should not be enabled and file not marked with @noflow

* fix: require-valid-file-annotation tests broken with new `checkFlowFileAnnotation` - respect onlyFilesWithFlowAnnotation == true

Co-authored-by: Gajus Kuizinas <gajus@gajus.com>

src/index.js

@@ -88,7 +88,7 @@ export default {
     recommended,
   },
   rules: _.mapValues(rules, (rule, key) => {
-    if (key === 'no-types-missing-file-annotation') {
+    if (['no-types-missing-file-annotation', 'require-valid-file-annotation'].includes(key)) {
       return rule;
     }
 

src/rules/requireValidFileAnnotation.js

@@ -113,7 +113,7 @@ const create = (context) => {
         } else {
           context.report(potentialFlowFileAnnotation, 'Malformed Flow file annotation.');
         }
-      } else if (always) {
+      } else if (always && !_.get(context, 'settings.flowtype.onlyFilesWithFlowAnnotation')) {
         context.report({
           fix: (fixer) => {
             let annotation;

src/utilities/checkFlowFileAnnotation.js

@@ -1,8 +1,9 @@
 import _ from 'lodash';
 import isFlowFile from './isFlowFile';
+import isNoFlowFile from './isNoFlowFile';
 
 export default (cb, context) => {
-  const checkThisFile = !_.get(context, 'settings.flowtype.onlyFilesWithFlowAnnotation') || isFlowFile(context);
+  const checkThisFile = (!_.get(context, 'settings.flowtype.onlyFilesWithFlowAnnotation') && !isNoFlowFile(context)) || isFlowFile(context); // eslint-disable-line no-extra-parens, max-len
 
   if (!checkThisFile) {
     return () => {};

src/utilities/index.js

@@ -9,6 +9,7 @@ export {default as getParameterName} from './getParameterName';
 export {default as getTokenAfterParens} from './getTokenAfterParens';
 export {default as getTokenBeforeParens} from './getTokenBeforeParens';
 export {default as isFlowFile} from './isFlowFile';
+export {default as isNoFlowFile} from './isNoFlowFile';
 export {default as isFlowFileAnnotation} from './isFlowFileAnnotation';
 export {default as iterateFunctionNodes} from './iterateFunctionNodes';
 export {default as quoteName} from './quoteName';

src/utilities/isNoFlowFile.js

@@ -0,0 +1,21 @@
+import isNoFlowFileAnnotation from './isNoFlowFileAnnotation';
+
+/**
+ * Checks whether a file has an @flow or @noflow annotation.
+ *
+ * @param context
+ * @param [strict] - By default, the function returns true if the file starts with @flow but not if it
+ * starts by @noflow. When the strict flag is set to false, the function returns true if the flag has @noflow also.
+ */
+
+export default (context, strict = true) => {
+  const comments = context.getAllComments();
+
+  if (!comments.length) {
+    return false;
+  }
+
+  return comments.some((comment) => {
+    return isNoFlowFileAnnotation(comment.value, strict);
+  });
+};

src/utilities/isNoFlowFileAnnotation.js

@@ -0,0 +1,17 @@
+import _ from 'lodash';
+
+const FLOW_MATCHER = /^@noflow$/;
+
+export default (comment, strict) => {
+  // The flow parser splits comments with the following regex to look for the @flow flag.
+  // See https://github.com/facebook/flow/blob/a96249b93541f2f7bfebd8d62085bf7a75de02f2/src/parsing/docblock.ml#L39
+  return _.some(comment.split(/[\t\n\r */\\]+/), (commentPart) => {
+    const match = commentPart.match(FLOW_MATCHER);
+
+    if (match === null) {
+      return false;
+    }
+
+    return !strict || match[0] === '@noflow';
+  });
+};

tests/rules/assertions/requireReturnType.js

@@ -38,6 +38,14 @@ export default {
         },
       ],
     },
+    {
+      code: '/* @flow */\n(foo) => { return 1; }',
+      errors: [
+        {
+          message: 'Missing return type annotation.',
+        },
+      ],
+    },
     {
       code: '(foo): undefined => { return; }',
       errors: [
@@ -692,6 +700,12 @@ export default {
         },
       },
     },
+    {
+      code: '/* @noflow */\n(foo) => { return 1; }',
+      options: [
+        'always',
+      ],
+    },
     {
       code: '(foo) => { return undefined; }',
       options: [