basic impl of typescript-eslint#8979

kirkwaiblinger · May 3, 2024 · 15406c4 · 15406c4
1 parent 9cb9a4d
commit 15406c4
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Showing 2 changed files with 168 additions and 14 deletions.
diff --git a/packages/eslint-plugin/src/rules/prefer-array-at.ts b/packages/eslint-plugin/src/rules/prefer-array-at.ts
@@ -1,11 +1,12 @@
 import type { TSESTree } from '@typescript-eslint/utils';
 import { AST_NODE_TYPES } from '@typescript-eslint/utils';
-import { isIntrinsicNumberType } from 'ts-api-utils';
+import { isIntrinsicNumberType, unionTypeParts } from 'ts-api-utils';
 
 import {
   createRule,
   getConstrainedTypeAtLocation,
   getParserServices,
+  getWrappingFixer,
   nullThrows,
 } from '../util';
 
@@ -44,11 +45,14 @@ export default createRule({
         // 2. replaces the index access with the at method of the same value
 
         const { expression, typeAnnotation } = node;
-        if (expression.type !== AST_NODE_TYPES.MemberExpression) {
+        let memberExpression = expression;
+        while (memberExpression.type === AST_NODE_TYPES.ChainExpression) {
+          memberExpression = memberExpression.expression;
+        }
+        if (memberExpression.type !== AST_NODE_TYPES.MemberExpression) {
           return;
         }
 
-        const memberExpression = expression;
         if (!memberExpression.computed || memberExpression.optional) {
           return;
         }
@@ -74,8 +78,14 @@ export default createRule({
           return;
         }
 
+        const indexType = getConstrainedTypeAtLocation(services, index);
         if (
-          !isIntrinsicNumberType(getConstrainedTypeAtLocation(services, index))
+          !(
+            isIntrinsicNumberType(indexType) ||
+            unionTypeParts(indexType).every(unionPart =>
+              unionPart.isNumberLiteral(),
+            )
+          )
         ) {
           return;
         }
@@ -108,16 +118,12 @@ export default createRule({
           suggest: [
             {
               messageId: 'useArrayAtSuggestion',
-              fix: fixer => {
-                const indexText = context.sourceCode.getText(index);
-                const objectText = context.sourceCode.getText(
-                  memberExpression.object,
-                );
-                return fixer.replaceText(
-                  node,
-                  `${objectText}.at(${indexText})`,
-                );
-              },
+              fix: getWrappingFixer({
+                sourceCode: context.sourceCode,
+                node,
+                innerNode: [memberExpression.object, index],
+                wrap: (object, index) => `${object}.at(${index})`,
+              }),
             },
           ],
         });

diff --git a/packages/eslint-plugin/tests/rules/prefer-array-at.test.ts b/packages/eslint-plugin/tests/rules/prefer-array-at.test.ts
@@ -19,6 +19,20 @@ ruleTester.run('prefer-array-at', rule, {
 declare const nums: Array<number>;
 const maybeNum = nums['length'] as number | undefined;
     `,
+    `
+declare const index: number;
+const objectWithArray = {
+  array: [1, 2, 3],
+};
+const maybeNum = objectWithArray.array?.[index] as undefined | number;
+    `,
+    `
+declare const index: 12 | 13 | 'length';
+const objectWithArray = {
+  array: [1, 2, 3],
+};
+const maybeNum = objectWithArray?.array[index] as undefined | number;
+    `,
   ],
   invalid: [
     {
@@ -67,5 +81,139 @@ const maybeNum = nums.at(index);
         },
       ],
     },
+    {
+      code: `
+declare const index: number;
+const objectWithArray = {
+  array: [1, 2, 3],
+};
+const maybeNum = objectWithArray.array[index] as undefined | number;
+      `,
+      errors: [
+        {
+          messageId: 'preferArrayAt',
+          line: 6,
+          suggestions: [
+            {
+              messageId: 'useArrayAtSuggestion',
+              output: `
+declare const index: number;
+const objectWithArray = {
+  array: [1, 2, 3],
+};
+const maybeNum = objectWithArray.array.at(index);
+      `,
+            },
+          ],
+        },
+      ],
+    },
+    {
+      code: `
+declare const index: number;
+const objectWithArray = {
+  array: [1, 2, 3],
+};
+const maybeNum = objectWithArray?.array[index] as undefined | number;
+      `,
+      errors: [
+        {
+          messageId: 'preferArrayAt',
+          line: 6,
+          suggestions: [
+            {
+              messageId: 'useArrayAtSuggestion',
+              output: `
+declare const index: number;
+const objectWithArray = {
+  array: [1, 2, 3],
+};
+const maybeNum = objectWithArray?.array.at(index);
+      `,
+            },
+          ],
+        },
+      ],
+    },
+    {
+      code: `
+declare const index: number;
+const objectWithArray = {
+  array: [1, 2, 3],
+};
+const maybeNum = objectWithArray?.array[12] as undefined | number;
+      `,
+      errors: [
+        {
+          messageId: 'preferArrayAt',
+          line: 6,
+          suggestions: [
+            {
+              messageId: 'useArrayAtSuggestion',
+              output: `
+declare const index: number;
+const objectWithArray = {
+  array: [1, 2, 3],
+};
+const maybeNum = objectWithArray?.array.at(12);
+      `,
+            },
+          ],
+        },
+      ],
+    },
+    {
+      code: `
+declare const index: 12 | 13;
+const objectWithArray = {
+  array: [1, 2, 3],
+};
+const maybeNum = objectWithArray?.array[index] as undefined | number;
+      `,
+      errors: [
+        {
+          messageId: 'preferArrayAt',
+          line: 6,
+          suggestions: [
+            {
+              messageId: 'useArrayAtSuggestion',
+              output: `
+declare const index: 12 | 13;
+const objectWithArray = {
+  array: [1, 2, 3],
+};
+const maybeNum = objectWithArray?.array.at(index);
+      `,
+            },
+          ],
+        },
+      ],
+    },
+    {
+      code: `
+declare const arr1: Array<number>;
+declare const arr2: Array<number>;
+declare const index: number;
+const maybeNum = (Math.random() > 0.5 ? arr1 : arr2)[index] as
+  | number
+  | undefined;
+      `,
+      errors: [
+        {
+          messageId: 'preferArrayAt',
+          suggestions: [
+            {
+              messageId: 'useArrayAtSuggestion',
+              output: `
+declare const arr1: Array<number>;
+declare const arr2: Array<number>;
+declare const index: number;
+const maybeNum = (Math.random() > 0.5 ? arr1 : arr2).at(index);
+      `,
+            },
+          ],
+        },
+      ],
+    },
   ],
 });