Initial commit

__tests__/main.test.ts

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+/**
+ * Unit tests for the action's main functionality, src/main.ts
+ *
+ * To mock dependencies in ESM, you can create fixtures that export mock
+ * functions and objects. For example, the core module is mocked in this test,
+ * so that the actual '@actions/core' module is not imported.
+ */
+import { jest } from '@jest/globals';
+import * as core from '../__fixtures__/core.js';
+
+// Mocks should be declared before the module being tested is imported.
+jest.unstable_mockModule('@actions/core', () => core);
+
+// The module being tested should be imported dynamically. This ensures that the
+// mocks are used in place of any actual dependencies.
+const { run } = await import('../src/main.js');
+
+describe('main.ts', () => {
+  beforeEach(() => {
+    // Set the action's inputs as return values from core.getInput().
+    core.getInput.mockImplementation(() => '500');
+  });
+
+  afterEach(() => {
+    jest.resetAllMocks();
+  });
+
+  it('Reads only one input', async () => {
+    await run();
+
+    expect(core.getInput).toHaveBeenCalledTimes(1);
+  });
+});