Move stripQuotes logic to no-unused-prop-types as well and add a test case

Author: jseminck

lib/rules/no-unused-prop-types.js

@@ -258,6 +258,17 @@ module.exports = {
       return tokens.length && tokens[0].value === '...';
     }
 
+    /**
+     * Removes quotes from around an identifier.
+     * @param {string} the identifier to strip
+     */
+    function stripQuotes(string) {
+      if (string[0] === '\'' || string[0] === '"' && string[0] === string[string.length - 1]) {
+        return string.slice(1, string.length - 1);
+      }
+      return string;
+    }
+
     /**
      * Retrieve the name of a key node
      * @param {ASTNode} node The AST node with the key.
@@ -266,7 +277,7 @@ module.exports = {
     function getKeyValue(node) {
       if (node.type === 'ObjectTypeProperty') {
         const tokens = context.getFirstTokens(node, {count: 1, filter: tokenNode => ['Identifier', 'String'].includes(tokenNode.type)});
-        return tokens[0].value;
+        return stripQuotes(tokens[0].value);
       }
       const key = node.key || node.argument;
       return key.type === 'Identifier' ? key.name : key.value;

tests/lib/rules/no-unused-prop-types.js

@@ -2067,6 +2067,16 @@ ruleTester.run('no-unused-prop-types', rule, {
         }
       `,
       parser: 'babel-eslint'
+    }, {
+      code: `
+        type Props = {
+          \'completed?\': boolean,
+        };
+        const Hello = (props: Props): React.Element => {
+          return <div>{props[\'completed?\']}</div>;
+        }
+      `,
+      parser: 'babel-eslint'
     }
   ],