### Question:
CommonCourtUtils { public static boolean isValidCommonCourtCode(String courtCode) { return StringUtils.isNumeric(courtCode) && courtCode.length() == 8 && courtCode.startsWith("15"); } private  CommonCourtUtils(); static boolean isValidCommonCourtCode(String courtCode); static String extractAppealCourtNumber(String courtCode); static String extractRegionalCourtNumber(String courtCode); static String extractDistrictCourtNumber(String courtCode); static CommonCourtType extractType(String courtCode);  }### Answer:
@Test public void isValidCommonCourtCode_NotNumeric() { assertFalse(CommonCourtUtils.isValidCommonCourtCode("150012A3")); }
@Test public void isValidCommonCourtCode_LengthNot8() { assertFalse(CommonCourtUtils.isValidCommonCourtCode("150012031")); }
@Test public void isValidCommonCourtCode_DoesNotStartWith15() { assertFalse(CommonCourtUtils.isValidCommonCourtCode("11001203")); }
@Test public void isValidCommonCourtCode_Valid() { assertTrue(CommonCourtUtils.isValidCommonCourtCode("15001203")); }