fix(eslint-plugin): [return-await] do not auto-fix when type is any/unknown (typescript-eslint#2671)

Author: thomasmichaelwallace

packages/eslint-plugin/src/rules/return-await.ts

@@ -1,7 +1,7 @@
 import {
   AST_NODE_TYPES,
-  TSESTree,
   TSESLint,
+  TSESTree,
 } from '@typescript-eslint/experimental-utils';
 import * as tsutils from 'tsutils';
 import * as ts from 'typescript';
@@ -170,10 +170,26 @@ export default util.createRule({
       }
 
       if (isAwait && !isThenable) {
+        // any/unknown could be thenable; do not auto-fix
+        const useAutoFix = !(
+          util.isTypeAnyType(type) || util.isTypeUnknownType(type)
+        );
+        const fix = (fixer: TSESLint.RuleFixer): TSESLint.RuleFix | null =>
+          removeAwait(fixer, node);
+
         context.report({
           messageId: 'nonPromiseAwait',
           node,
-          fix: fixer => removeAwait(fixer, node),
+          ...(useAutoFix
+            ? { fix }
+            : {
+                suggest: [
+                  {
+                    messageId: 'nonPromiseAwait',
+                    fix,
+                  },
+                ],
+              }),
         });
         return;
       }

packages/eslint-plugin/tests/rules/return-await.test.ts

@@ -1,5 +1,5 @@
 import rule from '../../src/rules/return-await';
-import { getFixturesRootDir, RuleTester, noFormat } from '../RuleTester';
+import { getFixturesRootDir, noFormat, RuleTester } from '../RuleTester';
 
 const rootDir = getFixturesRootDir();
 
@@ -312,6 +312,56 @@ ruleTester.run('return-await', rule, {
         },
       ],
     },
+    {
+      code: `
+const fn = (): any => null;
+async function test() {
+  return await fn();
+}
+      `.trimRight(),
+      errors: [
+        {
+          line: 4,
+          messageId: 'nonPromiseAwait',
+          suggestions: [
+            {
+              messageId: 'nonPromiseAwait',
+              output: `
+const fn = (): any => null;
+async function test() {
+  return fn();
+}
+              `.trimRight(),
+            },
+          ],
+        },
+      ],
+    },
+    {
+      code: `
+const fn = (): unknown => null;
+async function test() {
+  return await fn();
+}
+      `.trimRight(),
+      errors: [
+        {
+          line: 4,
+          messageId: 'nonPromiseAwait',
+          suggestions: [
+            {
+              messageId: 'nonPromiseAwait',
+              output: `
+const fn = (): unknown => null;
+async function test() {
+  return fn();
+}
+              `.trimRight(),
+            },
+          ],
+        },
+      ],
+    },
     {
       code: 'const test = async () => await Promise.resolve(1);',
       output: 'const test = async () => Promise.resolve(1);',