### Question:
Line { public boolean isEmpty() { return !CharMatcher.whitespace().negate().matchesAnyOf(text); } Line(int lineNumber, int offset, String text); boolean isEmpty(); String getText(); int getOffset(); int getLineNumber(); Line segment(int offset, int length); Locator toLocator(); @Override String toString();  }### Answer:
@Test public void isEmpty() { assertEmpty(""); assertEmpty("\t"); assertEmpty(" "); assertNotEmpty("a"); assertNotEmpty(" a"); assertNotEmpty("a "); }