test: add unit tests for OSV_OFFLINE_DATABASE_URL env variable (#1)

* test: add unit tests for OSV_OFFLINE_DATABASE_URL env variable

* fix: rename download.spec.ts to download.unit.spec.ts

---------

Co-authored-by: Mikael Olausson <mikael@Mikaels-MacBook-Air.local>

Author: mikaello

packages/osv-offline/src/lib/download.unit.spec.ts

@@ -0,0 +1,58 @@
+import { OsvOfflineDb } from '@renovatebot/osv-offline-db';
+import fs from 'fs-extra';
+import got from 'got';
+import path from 'path';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { tryDownloadDb } from './download';
+
+vi.mock('got', () => ({
+  default: {
+    stream: vi.fn(),
+  },
+}));
+
+describe('packages/osv-offline/src/lib/download.unit', () => {
+  describe('tryDownloadDb', () => {
+    beforeEach(async () => {
+      delete process.env.OSV_OFFLINE_DISABLE_DOWNLOAD;
+      delete process.env.OSV_OFFLINE_DATABASE_URL;
+      const zipFilePath = path.join(
+        OsvOfflineDb.rootDirectory,
+        'osv-offline.zip'
+      );
+      await fs.rm(zipFilePath, { force: true });
+      vi.clearAllMocks();
+    });
+
+    afterEach(() => {
+      vi.restoreAllMocks();
+    });
+
+    it('uses default URL when OSV_OFFLINE_DATABASE_URL is not set', async () => {
+      vi.mocked(got.stream).mockImplementationOnce(() => {
+        throw new Error('intentional stream error');
+      });
+
+      const result = await tryDownloadDb();
+
+      expect(result.success).toBe(false);
+      expect(vi.mocked(got.stream)).toHaveBeenCalledWith(
+        'https://github.com/renovatebot/osv-offline/releases/latest/download/osv-offline.zip'
+      );
+    });
+
+    it('uses OSV_OFFLINE_DATABASE_URL when set', async () => {
+      const customUrl = 'https://example.com/custom-db.zip';
+      process.env.OSV_OFFLINE_DATABASE_URL = customUrl;
+
+      vi.mocked(got.stream).mockImplementationOnce(() => {
+        throw new Error('intentional stream error');
+      });
+
+      const result = await tryDownloadDb();
+
+      expect(result.success).toBe(false);
+      expect(vi.mocked(got.stream)).toHaveBeenCalledWith(customUrl);
+    });
+  });
+});