fix: ignore vars with non-identifier references in no-useless-assignment (#19200)

yeonjuan · web-flow · commit c61870715e5b · 2024-12-04T10:44:18.000-05:00
* feat: check only Identifier's reference in `no-useless-assignment`

* review

* add test cases

* review
diff --git a/lib/rules/no-useless-assignment.js b/lib/rules/no-useless-assignment.js
@@ -309,6 +309,15 @@ module.exports = {
                 }
 
 
+                if (targetAssignment.variable.references.some(ref => ref.identifier.type !== "Identifier")) {
+
+                    /**
+                     * Skip checking for a variable that has at least one non-identifier reference.
+                     * It's generated by plugins and cannot be handled reliably in the core rule.
+                     */
+                    return;
+                }
+
                 const readReferences = targetAssignment.variable.references.filter(reference => reference.isRead());
 
                 if (!readReferences.length) {
diff --git a/tests/lib/rules/no-useless-assignment.js b/tests/lib/rules/no-useless-assignment.js
@@ -11,6 +11,7 @@
 
 const rule = require("../../../lib/rules/no-useless-assignment");
 const RuleTester = require("../../../lib/rule-tester/rule-tester");
+const { Reference } = require("eslint-scope");
 
 //------------------------------------------------------------------------------
 // Tests
@@ -30,6 +31,21 @@ const ruleTester = new RuleTester({
                             }
                         };
                     }
+                },
+                jsx: {
+                    create(context) {
+                        const sourceCode = context.sourceCode;
+
+                        return {
+                            JSXIdentifier(node) {
+                                const scope = sourceCode.getScope(node);
+                                const variable = scope.variables.find(v => v.name === node.name);
+
+                                variable.references.push(new Reference(node, scope, Reference.READ, null, false, null));
+
+                            }
+                        };
+                    }
                 }
             }
         }
@@ -353,7 +369,57 @@ ruleTester.run("no-useless-assignment", rule, {
         } = obj;
         console.log(a, b);`,
         `let { a, b: {c = a} = {} } = obj;
-        console.log(c);`
+        console.log(c);`,
+        {
+            code: `/*eslint test/jsx:1*/
+                function App() {
+                    const A = "";
+                    return <A/>;
+                }
+            `,
+            languageOptions: {
+                parserOptions: {
+                    ecmaFeatures: {
+                        jsx: true
+                    }
+                }
+            }
+        },
+        {
+            code: `/*eslint test/jsx:1*/
+                function App() {
+                    let A = "";
+                    foo(A);
+                    A = "A";
+                    return <A/>;
+                }
+            `,
+            languageOptions: {
+                parserOptions: {
+                    ecmaFeatures: {
+                        jsx: true
+                    }
+                }
+            }
+        },
+        {
+            code: `/*eslint test/jsx:1*/
+                function App() {
+                    let A = "a";
+                    A = "b";
+                    A = "c";
+                    foo(A);
+                    return <A/>;
+                }
+            `,
+            languageOptions: {
+                parserOptions: {
+                    ecmaFeatures: {
+                        jsx: true
+                    }
+                }
+            }
+        }
     ],
     invalid: [
         {
