assertThat(Strings.commonPrefix("xyz", "abcde")).isEqualTo("");
    assertThat(Strings.commonPrefix("xyz", "abcxyz")).isEqualTo("");
    assertThat(Strings.commonPrefix("abc", "aaaaa")).isEqualTo("a");
    assertThat(Strings.commonPrefix("aa", "aaaaa")).isEqualTo("aa");
    assertThat(Strings.commonPrefix(new StringBuilder("abcdef"), "abcxyz")).isEqualTo("abc");

    // Identical valid surrogate pairs.

    assertThat(Strings.commonPrefix("xyz", "abcde")).isEqualTo("");
    assertThat(Strings.commonPrefix("xyz", "abcxyz")).isEqualTo("");
    assertThat(Strings.commonPrefix("abc", "aaaaa")).isEqualTo("a");
    assertThat(Strings.commonPrefix("aa", "aaaaa")).isEqualTo("aa");
    assertThat(Strings.commonPrefix(new StringBuilder("abcdef"), "abcxyz")).isEqualTo("abc");

    // Identical valid surrogate pairs.

  private static final String ALMOST_TOO_MANY_LEVELS = Strings.repeat("a.", 127);

  @SuppressWarnings("InlineMeInliner") // String.repeat unavailable under Java 8
  private static final String ALMOST_TOO_LONG = Strings.repeat("aaaaa.", 40) + "1234567890.c";

  private static final ImmutableSet<String> VALID_NAME =
      ImmutableSet.of(
          // keep-sorted start
          "123.cn",
          "8server.shop",
          "a" + DELTA + "b.com",

  private static final String ALMOST_TOO_MANY_LEVELS = Strings.repeat("a.", 127);

  @SuppressWarnings("InlineMeInliner") // String.repeat unavailable under Java 8
  private static final String ALMOST_TOO_LONG = Strings.repeat("aaaaa.", 40) + "1234567890.c";

  private static final ImmutableSet<String> VALID_NAME =
      ImmutableSet.of(
          // keep-sorted start
          "123.cn",
          "8server.shop",
          "a" + DELTA + "b.com",

        final List<LlmMessage> history = new ArrayList<>();
        history.add(LlmMessage.user("QQQQQ")); // 5
        history.add(LlmMessage.assistant("AAAAA")); // 5
        history.add(LlmMessage.user("RRRRR")); // 5
        history.add(LlmMessage.assistant("SSSSS")); // 5
        history.add(LlmMessage.user("TTTTT")); // 5
        history.add(LlmMessage.assistant("UUUUU")); // 5

    assertValue("f", "f", "f")
    assertValue("g", "g", "g")
  }

  @Test
  fun cacheSingleEntryOfSizeGreaterThanMaxSize() {
    cache.close()
    createNewCacheWithSize(10)
    set("a", "aaaaa", "aaaaaa") // size=11
    cache.flush()
    assertAbsent("a")
  }

  @Test
  fun cacheSingleValueOfSizeGreaterThanMaxSize() {
    cache.close()
    createNewCacheWithSize(10)