Fix ESM compatibility with @actions v3 packages using module mapping

Co-authored-by: shati-patel <42641846+shati-patel@users.noreply.github.com>

Author: Copilot

jest-resolver.cjs

@@ -0,0 +1,22 @@
+/**
+ * Custom Jest resolver to handle ESM packages from @actions
+ */
+
+module.exports = (request, options) => {
+  // Use Jest's default resolver
+  return options.defaultResolver(request, {
+    ...options,
+    // Add package condition for node environment
+    packageFilter: (pkg) => {
+      // For ESM packages that have conditional exports, ensure we resolve correctly
+      if (pkg.exports && typeof pkg.exports === 'object') {
+        // If the package has exports, ensure we're using the right conditions
+        const conditions = options.conditions || [];
+        if (!conditions.includes('node')) {
+          options.conditions = [...conditions, 'node', 'import', 'require', 'default'];
+        }
+      }
+      return pkg;
+    },
+  });
+};

jest.config.ts

@@ -83,6 +83,14 @@ const config: Config = {
   // A map from regular expressions to module names or to arrays of module names that allow to stub out resources with a single module
   moduleNameMapper: {
     "^(\\.{1,2}/.*)\\.js$": "$1",
+    "^@actions/core$": "<rootDir>/node_modules/@actions/core/lib/core.js",
+    "^@actions/io$": "<rootDir>/node_modules/@actions/io/lib/io.js",
+    "^@actions/io/lib/(.*)$": "<rootDir>/node_modules/@actions/io/lib/$1",
+    "^@actions/exec$": "<rootDir>/node_modules/@actions/exec/lib/exec.js",
+    "^@actions/exec/lib/(.*)$": "<rootDir>/node_modules/@actions/exec/lib/$1",
+    "^@actions/http-client$": "<rootDir>/node_modules/@actions/http-client/lib/index.js",
+    "^@actions/http-client/lib/(.*)$": "<rootDir>/node_modules/@actions/http-client/lib/$1",
+    "^@actions/core/lib/(.*)$": "<rootDir>/node_modules/@actions/core/node_modules/@actions/http-client/lib/$1",
   },
 
   // An array of regexp pattern strings, matched against all module paths before considered 'visible' to the module loader
@@ -95,14 +103,14 @@ const config: Config = {
   // notifyMode: "failure-change",
 
   // A preset that is used as a base for Jest's configuration
-  preset: "ts-jest/presets/default-esm",
-
-  // An array of file extensions your modules use
-  extensionsToTreatAsEsm: [".ts"],
+  preset: "ts-jest",
 
   // Run tests from one or more projects
   // projects: undefined,
 
+  // A path to a custom resolver
+  resolver: "<rootDir>/jest-resolver.cjs",
+
   // Use this configuration option to add custom reporters to Jest
   // reporters: undefined,
 
@@ -179,10 +187,20 @@ const config: Config = {
       },
     ],
     "^.+\\.(js|jsx|mjs|cjs)$": [
-      "babel-jest",
+      "@swc/jest",
       {
-        presets: ["@babel/preset-env"],
-        plugins: ["@babel/plugin-transform-modules-commonjs"],
+        jsc: {
+          parser: {
+            syntax: "ecmascript",
+          },
+          transform: {
+            useDefineForClassFields: false,
+          },
+          target: "es2022",
+        },
+        module: {
+          type: "commonjs",
+        },
       },
     ],
   },

package-lock.json

@@ -41,6 +41,8 @@
     "@eslint/eslintrc": "^3.3.3",
     "@eslint/js": "^9.39.2",
     "@octokit/types": "^16.0.0",
+    "@swc/core": "^1.15.11",
+    "@swc/jest": "^0.2.39",
     "@types/archiver": "^7.0.0",
     "@types/jest": "^30.0.0",
     "@types/node": "^25.2.0",