public void doubleX()
{
assertEquals("Input: doubleX(\"axxbb\")", true, exercises.DoubleX("axxbb"));
assertEquals("Input: doubleX(\"axaxax\")", false, exercises.DoubleX("axaxax"));
assertEquals("Input: doubleX(\"xxxxx\")", true, exercises.DoubleX("xxxxx"));
assertEquals("Input: doubleX(\"xaxxx\")", false, exercises.DoubleX("xaxxx"));
assertEquals("Input: doubleX(\"aaaax\")", false, exercises.DoubleX("aaaax"));
assertEquals("Input: doubleX(\"\")", false, exercises.DoubleX(""));
assertEquals("Input: doubleX(\"abc\")", false, exercises.DoubleX("abc"));
assertEquals("Input: doubleX(\"x\")", false, exercises.DoubleX("x"));
assertEquals("Input: doubleX(\"xx\")", true, exercises.DoubleX("xx"));
assertEquals("Input: doubleX(\"xax\")", false, exercises.DoubleX("xax"));
assertEquals("Input: doubleX(\"xaxx\")", false, exercises.DoubleX("xaxx"));
}
