Added support (without options ... which are still to come) for spread (ie. ...) arguments with keys to be considered as valid as explicit key attributes

Part of jsx-eslint#1753

Author: machineghost

lib/rules/jsx-key.js

@@ -45,7 +45,25 @@ module.exports = {
     const fragmentPragma = pragmaUtil.getFragmentFromContext(context);
 
     function checkIteratorElement(node) {
-      if (node.type === 'JSXElement' && !hasProp(node.openingElement.attributes, 'key')) {
+      if (node.type === 'JSXElement') {
+        const hasAKeyAttribute = hasProp(node.openingElement.attributes, 'key');
+
+        const hasASpreadArgumentWithAKeyProperty = node.openingElement
+          && node.openingElement.attributes
+          && node.openingElement.attributes.some(
+            ({argument}) => argument && argument.properties && argument.properties.some(
+              (property) => property.key.name === 'key'));
+
+        const hasAnObjectSpreadArgument = node.openingElement
+          && node.openingElement.attributes
+          && node.openingElement.attributes.some(
+            ({argument}) => argument && argument.type === 'Identifier');
+
+        const isValidElement = hasAKeyAttribute
+         || hasASpreadArgumentWithAKeyProperty
+         || hasAnObjectSpreadArgument;
+        if (isValidElement) return;
+
         context.report({
           node,
           message: 'Missing "key" prop for element in iterator'

tests/lib/rules/jsx-key.js

@@ -39,6 +39,8 @@ ruleTester.run('jsx-key', rule, {
     {code: 'fn()'},
     {code: '[1, 2, 3].map(function () {})'},
     {code: '<App />;'},
+    {code: '[1, 2, 3].map(x => <App {...{ key }} />);'},
+    {code: '[1, 2, 3].map(x => <App {...objectWithKey} />);'},
     {code: '[<App key={0} />, <App key={1} />];'},
     {code: '[1, 2, 3].map(function(x) { return <App key={x} /> });'},
     {code: '[1, 2, 3].map(x => <App key={x} />);'},