feat(eslint-plugin): [prefer-regexp-exec] add autofix (#3207)

packages/eslint-plugin/README.md

@@ -162,7 +162,7 @@ Pro Tip: For larger codebases you may want to consider splitting our linting int
 | [`@typescript-eslint/prefer-readonly`](./docs/rules/prefer-readonly.md)                                               | Requires that private members are marked as `readonly` if they're never modified outside of the constructor             |                    | :wrench: | :thought_balloon: |
 | [`@typescript-eslint/prefer-readonly-parameter-types`](./docs/rules/prefer-readonly-parameter-types.md)               | Requires that function parameters are typed as readonly to prevent accidental mutation of inputs                        |                    |          | :thought_balloon: |
 | [`@typescript-eslint/prefer-reduce-type-parameter`](./docs/rules/prefer-reduce-type-parameter.md)                     | Prefer using type parameter when calling `Array#reduce` instead of casting                                              |                    | :wrench: | :thought_balloon: |
-| [`@typescript-eslint/prefer-regexp-exec`](./docs/rules/prefer-regexp-exec.md)                                         | Enforce that `RegExp#exec` is used instead of `String#match` if no global flag is provided                              | :white_check_mark: |          | :thought_balloon: |
+| [`@typescript-eslint/prefer-regexp-exec`](./docs/rules/prefer-regexp-exec.md)                                         | Enforce that `RegExp#exec` is used instead of `String#match` if no global flag is provided                              | :white_check_mark: | :wrench: | :thought_balloon: |
 | [`@typescript-eslint/prefer-string-starts-ends-with`](./docs/rules/prefer-string-starts-ends-with.md)                 | Enforce the use of `String#startsWith` and `String#endsWith` instead of other equivalent methods of checking substrings |                    | :wrench: | :thought_balloon: |
 | [`@typescript-eslint/prefer-ts-expect-error`](./docs/rules/prefer-ts-expect-error.md)                                 | Recommends using `@ts-expect-error` over `@ts-ignore`                                                                   |                    | :wrench: |                   |
 | [`@typescript-eslint/promise-function-async`](./docs/rules/promise-function-async.md)                                 | Requires any function or method that returns a Promise to be marked async                                               |                    | :wrench: | :thought_balloon: |

packages/eslint-plugin/src/rules/prefer-regexp-exec.ts

@@ -1,9 +1,13 @@
-import { TSESTree } from '@typescript-eslint/experimental-utils';
+import {
+  AST_NODE_TYPES,
+  TSESTree,
+} from '@typescript-eslint/experimental-utils';
 import {
   createRule,
   getParserServices,
   getStaticValue,
   getTypeName,
+  getWrappingFixer,
 } from '../util';
 
 export default createRule({
@@ -12,6 +16,7 @@ export default createRule({
 
   meta: {
     type: 'suggestion',
+    fixable: 'code',
     docs: {
       description:
         'Enforce that `RegExp#exec` is used instead of `String#match` if no global flag is provided',
@@ -27,44 +32,103 @@ export default createRule({
 
   create(context) {
     const globalScope = context.getScope();
-    const service = getParserServices(context);
-    const typeChecker = service.program.getTypeChecker();
+    const parserServices = getParserServices(context);
+    const typeChecker = parserServices.program.getTypeChecker();
+    const sourceCode = context.getSourceCode();
 
     /**
      * Check if a given node is a string.
      * @param node The node to check.
      */
-    function isStringType(node: TSESTree.LeftHandSideExpression): boolean {
+    function isStringType(node: TSESTree.Expression): boolean {
       const objectType = typeChecker.getTypeAtLocation(
-        service.esTreeNodeToTSNodeMap.get(node),
+        parserServices.esTreeNodeToTSNodeMap.get(node),
       );
       return getTypeName(typeChecker, objectType) === 'string';
     }
 
+    /**
+     * Check if a given node is a RegExp.
+     * @param node The node to check.
+     */
+    function isRegExpType(node: TSESTree.Expression): boolean {
+      const objectType = typeChecker.getTypeAtLocation(
+        parserServices.esTreeNodeToTSNodeMap.get(node),
+      );
+      return getTypeName(typeChecker, objectType) === 'RegExp';
+    }
+
     return {
       "CallExpression[arguments.length=1] > MemberExpression.callee[property.name='match'][computed=false]"(
-        node: TSESTree.MemberExpression,
+        memberNode: TSESTree.MemberExpression,
       ): void {
-        const callNode = node.parent as TSESTree.CallExpression;
-        const arg = callNode.arguments[0];
-        const evaluated = getStaticValue(arg, globalScope);
+        const objectNode = memberNode.object;
+        const callNode = memberNode.parent as TSESTree.CallExpression;
+        const argumentNode = callNode.arguments[0];
+        const argumentValue = getStaticValue(argumentNode, globalScope);
+
+        if (!isStringType(objectNode)) {
+          return;
+        }
 
         // Don't report regular expressions with global flag.
         if (
-          evaluated &&
-          evaluated.value instanceof RegExp &&
-          evaluated.value.flags.includes('g')
+          argumentValue &&
+          argumentValue.value instanceof RegExp &&
+          argumentValue.value.flags.includes('g')
         ) {
           return;
         }
 
-        if (isStringType(node.object)) {
-          context.report({
-            node: callNode,
+        if (
+          argumentNode.type === AST_NODE_TYPES.Literal &&
+          typeof argumentNode.value == 'string'
+        ) {
+          const regExp = RegExp(argumentNode.value);
+          return context.report({
+            node: memberNode.property,
             messageId: 'regExpExecOverStringMatch',
+            fix: getWrappingFixer({
+              sourceCode,
+              node: callNode,
+              innerNode: [objectNode],
+              wrap: objectCode => `${regExp.toString()}.exec(${objectCode})`,
+            }),
+          });
+        }
+
+        if (isRegExpType(argumentNode)) {
+          return context.report({
+            node: memberNode.property,
+            messageId: 'regExpExecOverStringMatch',
+            fix: getWrappingFixer({
+              sourceCode,
+              node: callNode,
+              innerNode: [objectNode, argumentNode],
+              wrap: (objectCode, argumentCode) =>
+                `${argumentCode}.exec(${objectCode})`,
+            }),
           });
-          return;
         }
+
+        if (isStringType(argumentNode)) {
+          return context.report({
+            node: memberNode.property,
+            messageId: 'regExpExecOverStringMatch',
+            fix: getWrappingFixer({
+              sourceCode,
+              node: callNode,
+              innerNode: [objectNode, argumentNode],
+              wrap: (objectCode, argumentCode) =>
+                `RegExp(${argumentCode}).exec(${objectCode})`,
+            }),
+          });
+        }
+
+        return context.report({
+          node: memberNode.property,
+          messageId: 'regExpExecOverStringMatch',
+        });
       },
     };
   },