chore(cache): minimize tar isolation diff

Restore the existing helper layout and separate test cases rather than
bundling unrelated consolidation with the bug fix. Leave archive creation
unchanged and retain only the read isolation, necessary path handling,
and regression coverage.

__tests__/tar.test.ts

@@ -84,56 +84,57 @@ test('zstd extract tar', async () => {
   )
 })
 
-test.each([
-  {operation: 'extract', read: tar.extractTar, flag: '-xf'},
-  {operation: 'list', read: tar.listTar, flag: '-tf'}
-])(
-  'zstd $operation tar with windows BSDtar',
-  async ({operation, read, flag}) => {
-    if (!IS_WINDOWS) {
-      return
-    }
+test('zstd extract tar with windows BSDtar', async () => {
+  if (IS_WINDOWS) {
     const mkdirMock = jest.spyOn(io, 'mkdirP')
     const execMock = jest.spyOn(exec, 'exec')
     const tempDirectory = getTempDir()
     jest.spyOn(utils, 'createTempDirectory').mockResolvedValue(tempDirectory)
-    jest.spyOn(utils, 'getGnuTarPathOnWindows').mockResolvedValue('')
+    jest
+      .spyOn(utils, 'getGnuTarPathOnWindows')
+      .mockReturnValue(Promise.resolve(''))
 
     const archivePath = `${process.env['windir']}\\fakepath\\cache.tar`
     const workspace = process.env['GITHUB_WORKSPACE']
-    const options = {
-      cwd: tempDirectory,
-      env: expect.objectContaining(defaultEnv)
-    }
-    const tarArgs = [`"${SystemTarPathOnWindows}"`, flag, TarFilename, '-P']
-    if (operation === 'extract') {
-      tarArgs.push('-C', `"${workspace?.replace(/\\/g, '/')}"`)
-    }
+    const tarPath = SystemTarPathOnWindows
 
-    await read(archivePath, CompressionMethod.Zstd)
+    await tar.extractTar(archivePath, CompressionMethod.Zstd)
 
-    if (operation === 'extract') {
-      expect(mkdirMock).toHaveBeenCalledWith(workspace)
-    }
+    expect(mkdirMock).toHaveBeenCalledWith(workspace)
     expect(execMock).toHaveBeenCalledTimes(2)
+
     expect(execMock).toHaveBeenNthCalledWith(
       1,
       [
         'zstd -d --long=30 --force -o',
-        TarFilename,
-        `"${archivePath.replace(/\\/g, '/')}"`
+        TarFilename.replace(new RegExp(`\\${path.sep}`, 'g'), '/'),
+        `"${archivePath.replace(new RegExp(`\\${path.sep}`, 'g'), '/')}"`
       ].join(' '),
       undefined,
-      options
+      {
+        cwd: tempDirectory,
+        env: expect.objectContaining(defaultEnv)
+      }
     )
+
     expect(execMock).toHaveBeenNthCalledWith(
       2,
-      tarArgs.join(' '),
+      [
+        `"${tarPath}"`,
+        '-xf',
+        TarFilename.replace(new RegExp(`\\${path.sep}`, 'g'), '/'),
+        '-P',
+        '-C',
+        `"${workspace?.replace(/\\/g, '/')}"`
+      ].join(' '),
       undefined,
-      options
+      {
+        cwd: tempDirectory,
+        env: expect.objectContaining(defaultEnv)
+      }
     )
   }
-)
+})
 
 test('gzip extract tar', async () => {
   const mkdirMock = jest.spyOn(io, 'mkdirP')
@@ -279,7 +280,7 @@ test('zstd create tar with windows BSDtar', async () => {
         TarFilename.replace(/\\/g, '/'),
         '-P',
         '-C',
-        `"${workspace?.replace(/\\/g, '/')}"`,
+        workspace?.replace(/\\/g, '/'),
         '--files-from',
         ManifestFilename
       ].join(' '),
@@ -379,6 +380,52 @@ test('zstd list tar', async () => {
   )
 })
 
+test('zstd list tar with windows BSDtar', async () => {
+  if (IS_WINDOWS) {
+    const execMock = jest.spyOn(exec, 'exec')
+    const tempDirectory = getTempDir()
+    jest.spyOn(utils, 'createTempDirectory').mockResolvedValue(tempDirectory)
+    jest
+      .spyOn(utils, 'getGnuTarPathOnWindows')
+      .mockReturnValue(Promise.resolve(''))
+    const archivePath = `${process.env['windir']}\\fakepath\\cache.tar`
+
+    await tar.listTar(archivePath, CompressionMethod.Zstd)
+
+    const tarPath = SystemTarPathOnWindows
+    expect(execMock).toHaveBeenCalledTimes(2)
+
+    expect(execMock).toHaveBeenNthCalledWith(
+      1,
+      [
+        'zstd -d --long=30 --force -o',
+        TarFilename.replace(new RegExp(`\\${path.sep}`, 'g'), '/'),
+        `"${archivePath.replace(new RegExp(`\\${path.sep}`, 'g'), '/')}"`
+      ].join(' '),
+      undefined,
+      {
+        cwd: tempDirectory,
+        env: expect.objectContaining(defaultEnv)
+      }
+    )
+
+    expect(execMock).toHaveBeenNthCalledWith(
+      2,
+      [
+        `"${tarPath}"`,
+        '-tf',
+        TarFilename.replace(new RegExp(`\\${path.sep}`, 'g'), '/'),
+        '-P'
+      ].join(' '),
+      undefined,
+      {
+        cwd: tempDirectory,
+        env: expect.objectContaining(defaultEnv)
+      }
+    )
+  }
+})
+
 test('zstdWithoutLong list tar', async () => {
   const execMock = jest.spyOn(exec, 'exec')