tests: add unit tests

.eslintrc.js

@@ -3,7 +3,7 @@ module.exports = {
   parser: "@typescript-eslint/parser",
   parserOptions: {
     tsconfigRootDir: __dirname,
-    project: ["./tsconfig.json"],
+    project: ["./tsconfig.json", "./tsconfig.test.json"],
   },
   plugins: ["@typescript-eslint"],
   extends: [
@@ -13,4 +13,7 @@ module.exports = {
     "plugin:@typescript-eslint/recommended-requiring-type-checking",
     "prettier",
   ],
+  env: {
+    node: true
+  }
 };

jest.config.js

@@ -1,5 +1,12 @@
-/** @type {import('ts-jest/dist/types').InitialOptionsTsJest} */
+/** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
-  preset: 'ts-jest',
-  testEnvironment: 'node',
-};
+  // [...]
+  transform: {
+    '^.+\\.ts$': [
+      'ts-jest',
+      {
+        tsconfig: 'tsconfig.test.json',
+      },
+    ],
+  },
+}

package.json

@@ -32,6 +32,7 @@
     "@actions/github": "5.1.1"
   },
   "devDependencies": {
+    "@jest/globals": "29.7.0",
     "@types/node": "18.18.4",
     "@typescript-eslint/eslint-plugin": "6.7.4",
     "@typescript-eslint/parser": "6.7.4",

src/index.test.ts

@@ -0,0 +1,34 @@
+import { beforeEach, describe, expect, it, jest } from "@jest/globals";
+
+describe("index", () => {
+  beforeEach(() => {
+    jest.resetModules();
+  });
+
+  it("calls run when imported", () => {
+    jest.doMock("./main", () => ({
+      run: jest.fn(() => Promise.resolve()),
+    }));
+
+    const { run } = require("./main"); // Import after setting up the mock
+    require("./index");
+
+    expect(run).toHaveBeenCalled();
+  });
+
+  it("sets action failed when there is an error", async () => {
+    jest.doMock("@actions/core", () => ({
+      setFailed: jest.fn(),
+    }));
+
+    const mockError = new Error("An error occurred");
+    jest.doMock("./main", () => ({
+      run: jest.fn(() => Promise.reject(mockError)),
+    }));
+
+    const { setFailed } = require("@actions/core"); // Import after setting up the mock
+    await require("./index");
+
+    expect(setFailed).toHaveBeenCalledWith(mockError)
+  });
+});

tsconfig.test.json

@@ -0,0 +1,5 @@
+{
+  "extends": "./tsconfig.json",
+  "exclude": ["node_modules", "dist"],
+  "include": ["**/*.test.ts"]
+}