Guard getErrorMessage suggestions by binding

eslint-factory/src/rules/prefer-get-error-message.test.ts

@@ -73,12 +73,19 @@ describe("prefer-get-error-message", () => {
     });
   });
 
-  it("invalid: basic ternary is flagged with suggestion", () => {
+  it("valid: ternary is not flagged when getErrorMessage is unavailable", () => {
+    cjsRuleTester.run("prefer-get-error-message", preferGetErrorMessageRule, {
+      valid: [`const errorMessage = err instanceof Error ? err.message : String(err);`],
+      invalid: [],
+    });
+  });
+
+  it("invalid: ternary is flagged with suggestion when getErrorMessage is previously imported", () => {
     cjsRuleTester.run("prefer-get-error-message", preferGetErrorMessageRule, {
       valid: [],
       invalid: [
         {
-          code: `const errorMessage = err instanceof Error ? err.message : String(err);`,
+          code: `const { getErrorMessage } = require("./error_helpers.cjs"); const errorMessage = err instanceof Error ? err.message : String(err);`,
           errors: [
             {
               messageId: "preferGetErrorMessage",
@@ -87,7 +94,7 @@ describe("prefer-get-error-message", () => {
                 {
                   messageId: "replaceWithGetErrorMessage",
                   data: { errorVar: "err" },
-                  output: `const errorMessage = getErrorMessage(err);`,
+                  output: `const { getErrorMessage } = require("./error_helpers.cjs"); const errorMessage = getErrorMessage(err);`,
                 },
               ],
             },
@@ -102,7 +109,7 @@ describe("prefer-get-error-message", () => {
       valid: [],
       invalid: [
         {
-          code: "core.warning(`failed: ${readErr instanceof Error ? readErr.message : String(readErr)}`);",
+          code: 'const { getErrorMessage } = require("./error_helpers.cjs"); core.warning(`failed: ${readErr instanceof Error ? readErr.message : String(readErr)}`);',
           errors: [
             {
               messageId: "preferGetErrorMessage",
@@ -111,7 +118,7 @@ describe("prefer-get-error-message", () => {
                 {
                   messageId: "replaceWithGetErrorMessage",
                   data: { errorVar: "readErr" },
-                  output: "core.warning(`failed: ${getErrorMessage(readErr)}`);",
+                  output: 'const { getErrorMessage } = require("./error_helpers.cjs"); core.warning(`failed: ${getErrorMessage(readErr)}`);',
                 },
               ],
             },
@@ -126,7 +133,7 @@ describe("prefer-get-error-message", () => {
       valid: [],
       invalid: [
         {
-          code: `console.error(e instanceof Error ? e.message : String(e));`,
+          code: `import { getErrorMessage } from "./error_helpers.cjs"; console.error(e instanceof Error ? e.message : String(e));`,
           errors: [
             {
               messageId: "preferGetErrorMessage",
@@ -135,7 +142,7 @@ describe("prefer-get-error-message", () => {
                 {
                   messageId: "replaceWithGetErrorMessage",
                   data: { errorVar: "e" },
-                  output: `console.error(getErrorMessage(e));`,
+                  output: `import { getErrorMessage } from "./error_helpers.cjs"; console.error(getErrorMessage(e));`,
                 },
               ],
             },

eslint-factory/src/rules/prefer-get-error-message.ts

@@ -1,4 +1,4 @@
-import { AST_NODE_TYPES, ESLintUtils, TSESTree } from "@typescript-eslint/utils";
+import { AST_NODE_TYPES, ESLintUtils, TSESLint, TSESTree } from "@typescript-eslint/utils";
 
 const createRule = ESLintUtils.RuleCreator(name => `https://github.com/github/gh-aw/tree/main/eslint-factory#${name}`);
 
@@ -22,6 +22,30 @@ export const preferGetErrorMessageRule = createRule({
   },
   defaultOptions: [],
   create(context) {
+    const sourceCode = context.sourceCode;
+    type Scope = ReturnType<typeof sourceCode.getScope>;
+
+    function isDefinitionAvailableAtNode(definition: TSESLint.Scope.Definition, node: TSESTree.Node): boolean {
+      if (definition.type === "ImportBinding" || definition.type === "FunctionName") {
+        return true;
+      }
+      const definitionNode = definition.name ?? definition.node;
+      if (!definitionNode?.range || !node.range) return false;
+      return definitionNode.range[0] < node.range[0];
+    }
+
+    function hasResolvableLocalBinding(node: TSESTree.Node, name: string): boolean {
+      let scope: Scope | null = sourceCode.getScope(node);
+      while (scope) {
+        const variable = scope.set.get(name);
+        if (variable && variable.defs.some(def => isDefinitionAvailableAtNode(def, node))) {
+          return true;
+        }
+        scope = scope.upper;
+      }
+      return false;
+    }
+
     return {
       ConditionalExpression(node) {
         const test = node.test;
@@ -38,6 +62,7 @@ export const preferGetErrorMessageRule = createRule({
         if (alternate.type !== AST_NODE_TYPES.CallExpression || !isIdentifierNamed(alternate.callee, "String") || alternate.arguments.length !== 1 || !isIdentifierNamed(alternate.arguments[0], errorVar)) {
           return;
         }
+        if (!hasResolvableLocalBinding(node, "getErrorMessage")) return;
 
         context.report({
           node,