fun assertNoNetworkResponse() =
    apply {
      assertThat(response!!.networkResponse).isNull()
    }

  /** Asserts that the current response didn't use the cache.  */
  fun assertNoCacheResponse() =
    apply {
      assertThat(response!!.cacheResponse).isNull()
    }

  /**
   * Asserts that the current response used the cache and returns the cache response.
   */

  fun onlyIfCachedReturns504WhenNotCached() {
    executeSynchronously("/", "Cache-Control", "only-if-cached")
      .assertCode(504)
      .assertBody("")
      .assertNoNetworkResponse()
      .assertNoCacheResponse()
  }

  @Test
  fun networkDropsOnConditionalGet() {
    client =
      client.newBuilder()
        .cache(cache)
        .build()

    // Seed the cache.