feat: support private mirrors

__tests__/official-installer.test.ts

@@ -828,4 +828,46 @@ describe('setup-node', () => {
       }
     );
   });
+
+  it('acquires specified architecture of node from mirror', async () => {
+    for (const {arch, version, osSpec} of [
+      {arch: 'x86', version: '12.16.2', osSpec: 'win32'},
+      {arch: 'x86', version: '14.0.0', osSpec: 'win32'}
+    ]) {
+      os.platform = osSpec;
+      os.arch = arch;
+      const fileExtension = os.platform === 'win32' ? '7z' : 'tar.gz';
+      const platform = {
+        linux: 'linux',
+        darwin: 'darwin',
+        win32: 'win'
+      }[os.platform];
+
+      inputs['node-version'] = version;
+      inputs['architecture'] = arch;
+      inputs['always-auth'] = false;
+      inputs['token'] = 'faketoken';
+      inputs['mirror'] = 'https://my_mirror_url';
+      inputs['mirror-token'] = 'faketoken';
+
+      const expectedUrl =
+        arch === 'x64'
+          ? `https://github.com/actions/node-versions/releases/download/${version}/node-${version}-${platform}-${arch}.zip`
+          : `https://my_mirror_url/dist/v${version}/node-v${version}-${platform}-${arch}.${fileExtension}`;
+
+      // ... but not in the local cache
+      findSpy.mockImplementation(() => '');
+
+      dlSpy.mockImplementation(async () => '/some/temp/path');
+      const toolPath = path.normalize(`/cache/node/${version}/${arch}`);
+      exSpy.mockImplementation(async () => '/some/other/temp/path');
+      cacheSpy.mockImplementation(async () => toolPath);
+
+      await main.run();
+      expect(dlSpy).toHaveBeenCalled();
+      expect(logSpy).toHaveBeenCalledWith(
+        `Acquiring ${version} - ${arch} from ${expectedUrl}`
+      );
+    }
+  }, 100000);
 });