Update to include additional examples

Expensify · Jul 8, 2024 · 6c9e140 · 6c9e140
1 parent 1db821d
commit 6c9e140
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Showing 2 changed files with 96 additions and 9 deletions.
diff --git a/eslint-plugin-expensify/prefer-at.js b/eslint-plugin-expensify/prefer-at.js
@@ -4,23 +4,78 @@ module.exports = {
     meta: {
         fixable: 'code',
     },
-
     create(context) {
-        return {
-            MemberExpression(node) {
-                // Check if we are accessing an array element directly
-                if (node.object.type === 'Identifier' && node.property.type === 'Literal' && typeof node.property.value === 'number') {
+        function isLiteralNumber(node) {
+            return node && node.type === 'Literal' && typeof node.value === 'number';
+        }
+
+        function isMemberExpressionWithLength(node) {
+            return (
+                node &&
+                node.type === 'MemberExpression' &&
+                node.property &&
+                node.property.type === 'Identifier' &&
+                node.property.name === 'length'
+            );
+        }
+
+        function checkNode(node) {
+            if (node.type === 'MemberExpression' && node.property) {
+                // Handle items cases like test[0]
+                if (isLiteralNumber(node.property)) {
+                    context.report({
+                        node,
+                        message,
+                        fix(fixer) {
+                            return fixer.replaceText(node, `${node.object.name}.at(${node.property.value})`);
+                        },
+                    });
+                }
+
+                // Handle items like test[test.length - 1]
+                if (
+                    node.property.type === 'BinaryExpression' &&
+                    node.property.operator === '-' &&
+                    isMemberExpressionWithLength(node.property.left) &&
+                    isLiteralNumber(node.property.right)
+                ) {
                     context.report({
                         node,
                         message,
                         fix(fixer) {
-                            const arrayName = node.object.name;
-                            const indexValue = node.property.value;
-                            return fixer.replaceText(node, `${arrayName}.at(${indexValue})`);
+                            const objectName = node.object.name;
+                            const offset = node.property.right.value;
+                            return fixer.replaceText(node, `${objectName}.at(-${offset})`);
                         },
                     });
                 }
-            },
+
+                // Handle items like test[(test.length - 1) / 2]
+                if (
+                    node.property.type === 'BinaryExpression' &&
+                    node.property.operator === '/' &&
+                    node.property.left.type === 'BinaryExpression' &&
+                    node.property.left.operator === '-' &&
+                    isMemberExpressionWithLength(node.property.left.left) &&
+                    isLiteralNumber(node.property.left.right) &&
+                    isLiteralNumber(node.property.right)
+                ) {
+                    context.report({
+                        node,
+                        message,
+                        fix(fixer) {
+                            const objectName = node.object.name;
+                            const leftValue = node.property.left.right.value;
+                            const rightValue = node.property.right.value;
+                            return fixer.replaceText(node, `${objectName}.at((${objectName}.length - ${leftValue}) / ${rightValue})`);
+                        },
+                    });
+                }
+            }
+        }
+
+        return {
+            MemberExpression: checkNode,
         };
     },
 };
diff --git a/eslint-plugin-expensify/tests/prefer-at.test.js b/eslint-plugin-expensify/tests/prefer-at.test.js
@@ -17,6 +17,18 @@ ruleTester.run('prefer-at', rule, {
         {
             code: 'test.at(1)',
         },
+        {
+            code: 'sample.at(-1)',
+        },
+        {
+            code: 'testing.at(-2)',
+        },
+        {
+            code: 'testing.at(0).at(-1)',
+        },
+        {
+            code: 'test.at((test.length - 1) / 2)',
+        },
     ],
     invalid: [
         {
@@ -33,5 +45,25 @@ ruleTester.run('prefer-at', rule, {
                 message,
             }],
         },
+        {
+            code: 'sample[sample.length-1]',
+            output: 'sample.at(-1)',
+            errors: [{
+                message,
+            }],
+        },{
+            code: 'testing[testing.length-2]',
+            output: 'testing.at(-2)',
+            errors: [{
+                message,
+            }],
+        },
+        {
+            code: 'test[(test.length - 1) / 2]',
+            output: 'test.at((test.length - 1) / 2)',
+            errors: [{
+                message,
+            }],
+        },
     ],
 });