From 7443a37fff3d2cfc77d9c4379e19bb0bc8266800 Mon Sep 17 00:00:00 2001
From: Ian Sutherland <ian@iansutherland.ca>
Date: Tue, 23 Jan 2018 14:56:58 -0700
Subject: [PATCH] [New] `forbid-foreign-prop-types`: Add `allowInPropTypes`
 option

Fixes #1647.
---
 lib/rules/forbid-foreign-prop-types.js       | 79 ++++++++++++++++----
 tests/lib/rules/forbid-foreign-prop-types.js | 36 ++++++++-
 2 files changed, 98 insertions(+), 17 deletions(-)

diff --git a/lib/rules/forbid-foreign-prop-types.js b/lib/rules/forbid-foreign-prop-types.js
index 0ea1e1bd64..5e83f891be 100644
--- a/lib/rules/forbid-foreign-prop-types.js
+++ b/lib/rules/forbid-foreign-prop-types.js
@@ -6,15 +6,6 @@
 
 const docsUrl = require('../util/docsUrl');
 
-// ------------------------------------------------------------------------------
-// Constants
-// ------------------------------------------------------------------------------
-
-
-// ------------------------------------------------------------------------------
-// Rule Definition
-// ------------------------------------------------------------------------------
-
 module.exports = {
   meta: {
     docs: {
@@ -22,10 +13,25 @@ module.exports = {
       category: 'Best Practices',
       recommended: false,
       url: docsUrl('forbid-foreign-prop-types')
-    }
+    },
+
+    schema: [
+      {
+        type: 'object',
+        properties: {
+          allowInPropTypes: {
+            type: 'boolean'
+          }
+        },
+        additionalProperties: false
+      }
+    ]
   },
 
   create: function(context) {
+    const config = context.options[0] || {};
+    const allowInPropTypes = config.allowInPropTypes || false;
+
     // --------------------------------------------------------------------------
     // Helpers
     // --------------------------------------------------------------------------
@@ -34,15 +40,56 @@ module.exports = {
       return node.parent.type === 'AssignmentExpression' && node.parent.left === node;
     }
 
+    function findParentAssignmentExpression(node) {
+      let parent = node.parent;
+
+      while (parent && parent.type !== 'Program') {
+        if (parent.type === 'AssignmentExpression') {
+          return parent;
+        }
+        parent = parent.parent;
+      }
+      return null;
+    }
+
+    function isAllowedAssignment(node) {
+      if (!allowInPropTypes) {
+        return false;
+      }
+
+      const assignmentExpression = findParentAssignmentExpression(node);
+
+      if (
+        assignmentExpression &&
+        assignmentExpression.left &&
+        assignmentExpression.left.property &&
+        assignmentExpression.left.property.name === 'propTypes'
+      ) {
+        return true;
+      }
+      return false;
+    }
+
     return {
       MemberExpression: function(node) {
-        if (!node.computed && node.property && node.property.type === 'Identifier' &&
-            node.property.name === 'propTypes' && !isLeftSideOfAssignment(node) ||
-            node.property && node.property.type === 'Literal' &&
-            node.property.value === 'propTypes' && !isLeftSideOfAssignment(node)) {
+        if (
+          node.property &&
+          (
+            !node.computed &&
+            node.property.type === 'Identifier' &&
+            node.property.name === 'propTypes' &&
+            !isLeftSideOfAssignment(node) &&
+            !isAllowedAssignment(node)
+          ) || (
+            node.property.type === 'Literal' &&
+            node.property.value === 'propTypes' &&
+            !isLeftSideOfAssignment(node) &&
+            !isAllowedAssignment(node)
+          )
+        ) {
           context.report({
             node: node.property,
-            message: 'Using another component\'s propTypes is forbidden'
+            message: 'Using propTypes from another component is not safe because they may be removed in production builds'
           });
         }
       },
@@ -53,7 +100,7 @@ module.exports = {
         if (propTypesNode) {
           context.report({
             node: propTypesNode,
-            message: 'Using another component\'s propTypes is forbidden'
+            message: 'Using propTypes from another component is not safe because they may be removed in production builds'
           });
         }
       }
diff --git a/tests/lib/rules/forbid-foreign-prop-types.js b/tests/lib/rules/forbid-foreign-prop-types.js
index b2c1c4a5de..8c081b2df6 100644
--- a/tests/lib/rules/forbid-foreign-prop-types.js
+++ b/tests/lib/rules/forbid-foreign-prop-types.js
@@ -25,7 +25,7 @@ require('babel-eslint');
 // Tests
 // -----------------------------------------------------------------------------
 
-const ERROR_MESSAGE = 'Using another component\'s propTypes is forbidden';
+const ERROR_MESSAGE = 'Using propTypes from another component is not safe because they may be removed in production builds';
 
 const ruleTester = new RuleTester({parserOptions});
 ruleTester.run('forbid-foreign-prop-types', rule, {
@@ -50,6 +50,21 @@ ruleTester.run('forbid-foreign-prop-types', rule, {
     code: 'Foo["propTypes"] = propTypes'
   }, {
     code: 'const propTypes = "bar"; Foo[propTypes];'
+  },
+  {
+    code: `
+      const Message = (props) => (<div>{props.message}</div>);
+      Message.propTypes = {
+        message: PropTypes.string
+      };
+      const Hello = (props) => (<Message>Hello {props.name}</Message>);
+      Hello.propTypes = {
+        name: Message.propTypes.message
+      };
+    `,
+    options: [{
+      allowInPropTypes: true
+    }]
   }],
 
   invalid: [{
@@ -139,5 +154,24 @@ ruleTester.run('forbid-foreign-prop-types', rule, {
       message: ERROR_MESSAGE,
       type: 'Property'
     }]
+  },
+  {
+    code: `
+      const Message = (props) => (<div>{props.message}</div>);
+      Message.propTypes = {
+        message: PropTypes.string
+      };
+      const Hello = (props) => (<Message>Hello {props.name}</Message>);
+      Hello.propTypes = {
+        name: Message.propTypes.message
+      };
+    `,
+    options: [{
+      allowInPropTypes: false
+    }],
+    errors: [{
+      message: ERROR_MESSAGE,
+      type: 'Identifier'
+    }]
   }]
 });