fix(eslint-plugin): [prefer-return-this-type] handle generics properly in fixer (typescript-eslint#3852)

rafaelss95 · web-flow · commit 9e98b8f43ca6 · 2021-09-20T23:42:54.000-07:00
diff --git a/packages/eslint-plugin/src/rules/prefer-return-this-type.ts b/packages/eslint-plugin/src/rules/prefer-return-this-type.ts
@@ -1,9 +1,9 @@
 import {
-  TSESTree,
   AST_NODE_TYPES,
+  TSESTree,
 } from '@typescript-eslint/experimental-utils';
-import { createRule, forEachReturnStatement, getParserServices } from '../util';
 import * as ts from 'typescript';
+import { createRule, forEachReturnStatement, getParserServices } from '../util';
 
 type ClassLikeDeclaration =
   | TSESTree.ClassDeclaration
@@ -40,13 +40,13 @@ export default createRule({
     function tryGetNameInType(
       name: string,
       typeNode: TSESTree.TypeNode,
-    ): TSESTree.Identifier | undefined {
+    ): TSESTree.TSTypeReference | undefined {
       if (
         typeNode.type === AST_NODE_TYPES.TSTypeReference &&
         typeNode.typeName.type === AST_NODE_TYPES.Identifier &&
         typeNode.typeName.name === name
       ) {
-        return typeNode.typeName;
+        return typeNode;
       }
 
       if (typeNode.type === AST_NODE_TYPES.TSUnionType) {
@@ -130,29 +130,23 @@ export default createRule({
       originalClass: ClassLikeDeclaration,
     ): void {
       const className = originalClass.id?.name;
-      if (!className) {
-        return;
-      }
-
-      if (!originalFunc.returnType) {
+      if (!className || !originalFunc.returnType) {
         return;
       }
 
-      const classNameRef = tryGetNameInType(
+      const node = tryGetNameInType(
         className,
         originalFunc.returnType.typeAnnotation,
       );
-      if (!classNameRef) {
+      if (!node) {
         return;
       }
 
       if (isFunctionReturningThis(originalFunc, originalClass)) {
         context.report({
-          node: classNameRef,
+          node,
           messageId: 'useThisType',
-          fix(fixer) {
-            return fixer.replaceText(classNameRef, 'this');
-          },
+          fix: fixer => fixer.replaceText(node, 'this'),
         });
       }
     }
diff --git a/packages/eslint-plugin/tests/rules/prefer-return-this-type.test.ts b/packages/eslint-plugin/tests/rules/prefer-return-this-type.test.ts
@@ -1,5 +1,5 @@
 import rule from '../../src/rules/prefer-return-this-type';
-import { RuleTester, getFixturesRootDir } from '../RuleTester';
+import { getFixturesRootDir, RuleTester } from '../RuleTester';
 
 const rootPath = getFixturesRootDir();
 
@@ -281,6 +281,33 @@ class Foo {
         return this;
     }
   }
+}
+      `,
+    },
+    {
+      // https://github.com/typescript-eslint/typescript-eslint/issues/3842
+      code: `
+class Animal<T> {
+  eat(): Animal<T> {
+    console.log("I'm moving!");
+    return this;
+  }
+}
+      `,
+      errors: [
+        {
+          messageId: 'useThisType',
+          line: 3,
+          column: 10,
+          endColumn: 19,
+        },
+      ],
+      output: `
+class Animal<T> {
+  eat(): this {
+    console.log("I'm moving!");
+    return this;
+  }
 }
       `,
     },
