StringExercises { public static int countLowercaseLetters(String string) { return (int) string.chars() .filter(Character::isLowerCase) .count(); }  static int countLowercaseLetters(String string); static Optional<String> mostLowercaseString(List<String> strings);  }
@Test public void noLowercaseLettersInAnEmptyString() { assertEquals(0, com.insightfullogic.java8.answers.chapter3.StringExercises.countLowercaseLetters("")); }
@Test public void countsLowercaseLetterExample() { assertEquals(3, com.insightfullogic.java8.answers.chapter3.StringExercises.countLowercaseLetters("aBcDeF")); }
@Test public void suppoertsNoLowercaseLetters() { assertEquals(0, com.insightfullogic.java8.answers.chapter3.StringExercises.countLowercaseLetters("ABCDEF")); }