String secondLine = "\\s*at " + ThrowablesTest.class.getName() + "\\..*";
    String moreLines = "(?:.*" + System.lineSeparator() + "?)*";
    String expected =
        firstLine + System.lineSeparator() + secondLine + System.lineSeparator() + moreLines;
    assertThat(getStackTraceAsString(e)).matches(expected);
  }

  public void testGetCausalChain() {

    String secondLine = "\\s*at " + ThrowablesTest.class.getName() + "\\..*";
    String moreLines = "(?:.*" + System.lineSeparator() + "?)*";
    String expected =
        firstLine + System.lineSeparator() + secondLine + System.lineSeparator() + moreLines;
    assertThat(getStackTraceAsString(e)).matches(expected);
  }

  public void testGetCausalChain() {

  public static CharMatcher javaIsoControl() {
    return JavaIsoControl.INSTANCE;
  }

  /**
   * Determines whether a character is invisible; that is, if its Unicode category is any of
   * SPACE_SEPARATOR, LINE_SEPARATOR, PARAGRAPH_SEPARATOR, CONTROL, FORMAT, SURROGATE, and
   * PRIVATE_USE according to ICU4J.
   *
   * <p>See also the Unicode Default_Ignorable_Code_Point property (available via ICU).
   *