switch from jest to vitest

tests/installer.test.ts

@@ -0,0 +1,40 @@
+import {describe, expect, it} from 'vitest';
+import * as fs from 'fs';
+
+import * as installer from '../src/installer';
+
+describe('getRelease', () => {
+  it('returns latest UPX GitHub release', async () => {
+    const release = await installer.getRelease('latest');
+    expect(release).not.toBeNull();
+    expect(release?.tag_name).not.toEqual('');
+  });
+
+  it('returns v3.95 UPX GitHub release', async () => {
+    const release = await installer.getRelease('v3.95');
+    expect(release).not.toBeNull();
+    expect(release?.id).toEqual(12577195);
+    expect(release?.tag_name).toEqual('v3.95');
+    expect(release?.html_url).toEqual('https://github.com/upx/upx/releases/tag/v3.95');
+  });
+
+  it('unknown release', async () => {
+    await expect(installer.getRelease('foo')).rejects.toThrow(
+      new Error(
+        'Cannot find UPX release foo in https://raw.githubusercontent.com/crazy-max/ghaction-upx/master/.github/upx-releases.json'
+      )
+    );
+  });
+});
+
+describe('installer', () => {
+  it('acquires v3.95 version of UPX', async () => {
+    const upx = await installer.getUPX('v3.95');
+    expect(fs.existsSync(upx)).toBe(true);
+  }, 100000);
+
+  it('acquires latest version of UPX', async () => {
+    const upx = await installer.getUPX('latest');
+    expect(fs.existsSync(upx)).toBe(true);
+  }, 100000);
+});