From 51f4ba227bd82c4cc70903c5dd26fc5a653c81e5 Mon Sep 17 00:00:00 2001
From: Kevin Grandon <kevingrandon@yahoo.com>
Date: Tue, 29 May 2018 12:04:26 -0700
Subject: [PATCH] feat: add fixer for requireValidFileAnnotation when always
 (#332)

* Add fixer for requireValidFileAnnotation when always

* Add autofix note in readme
---
 README.md                                     |  2 ++
 src/rules/requireValidFileAnnotation.js       | 14 +++++++++-
 .../assertions/requireValidFileAnnotation.js  | 27 +++++++++++++++++++
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 3bf06533..546725bb 100644
--- a/README.md
+++ b/README.md
@@ -2437,6 +2437,8 @@ This rule validates Flow file annotations.
 
 This rule can optionally report missing or missed placed annotations, common typos (e.g. `// @floww`), and enforce a consistant annotation style.
 
+This rule is autofixable with the `--fix` argument. This will autofix files by adding missing flow annotations to the top of each file. To avoid autofixing this rule per-file, you can add a `// @noflow` annotation to the top of individual files.
+
 <a name="eslint-plugin-flowtype-rules-require-valid-file-annotation-options"></a>
 #### Options
 
diff --git a/src/rules/requireValidFileAnnotation.js b/src/rules/requireValidFileAnnotation.js
index 9db7d623..4ffabd7b 100644
--- a/src/rules/requireValidFileAnnotation.js
+++ b/src/rules/requireValidFileAnnotation.js
@@ -49,6 +49,14 @@ const create = (context) => {
     Program (node) {
       const firstToken = node.tokens[0];
 
+      const addAnnotation = () => {
+        return (fixer) => {
+          const annotation = ['line', 'none'].includes(style) ? '// @flow\n' : '/* @flow */\n';
+
+          return fixer.replaceTextRange([node.start, node.start], annotation);
+        };
+      };
+
       const potentialFlowFileAnnotation = _.find(context.getAllComments(), (comment) => {
         return looksLikeFlowFileAnnotation(comment.value);
       });
@@ -70,7 +78,11 @@ const create = (context) => {
           context.report(potentialFlowFileAnnotation, 'Malformed Flow file annotation.');
         }
       } else if (always) {
-        context.report(node, 'Flow file annotation is missing.');
+        context.report({
+          fix: addAnnotation(),
+          message: 'Flow file annotation is missing.',
+          node
+        });
       }
     }
   };
diff --git a/tests/rules/assertions/requireValidFileAnnotation.js b/tests/rules/assertions/requireValidFileAnnotation.js
index c28983f5..57c5c1a3 100644
--- a/tests/rules/assertions/requireValidFileAnnotation.js
+++ b/tests/rules/assertions/requireValidFileAnnotation.js
@@ -122,6 +122,33 @@ export default {
           annotationStyle: 'block'
         }
       ]
+    },
+    {
+      code: 'a;',
+      errors: [
+        {
+          message: 'Flow file annotation is missing.'
+        }
+      ],
+      options: [
+        'always'
+      ],
+      output: '// @flow\na;'
+    },
+    {
+      code: 'a;',
+      errors: [
+        {
+          message: 'Flow file annotation is missing.'
+        }
+      ],
+      options: [
+        'always',
+        {
+          annotationStyle: 'block'
+        }
+      ],
+      output: '/* @flow */\na;'
     }
   ],
   misconfigured: [