*     we've successfully connected or because no further attempts should be made.
   */
  @Throws(IOException::class)
  internal fun connectTunnel(): ConnectResult {
    val nextTunnelRequest =
      createTunnel()
        ?: return ConnectResult(plan = this) // Success.

    // The proxy decided to close the connection after an auth challenge. Retry with different
    // auth credentials.
    rawSocket?.closeQuietly()

        when:
        createRunner().withTestKitDir(null)

        then:
        def t = thrown(IllegalArgumentException)
        t.message == 'testKitDir argument cannot be null'
    }

    def "can set custom test kit directory"() {
        given:
        def testKitDir = testDirectoryProvider.createDir('some/dir')

        when:
        def runner = createRunner()
            .withProjectDir(workingDir)