StringExercises { public static int countLowercaseLetters(String string) { return Exercises.replaceThisWithSolution(); }  static int countLowercaseLetters(String string); static Optional<String> mostLowercaseString(List<String> strings);  }
@Test public void noLowercaseLettersInAnEmptyString() { assertEquals(0, StringExercises.countLowercaseLetters("")); }
@Test public void countsLowercaseLetterExample() { assertEquals(3, StringExercises.countLowercaseLetters("aBcDeF")); }
@Test public void suppoertsNoLowercaseLetters() { assertEquals(0, StringExercises.countLowercaseLetters("ABCDEF")); }