### Question:
ValidationUtils { public static void contains(String sequence, String searchSequence, String property, String messagePrefix, Errors error) { if (!StringUtils.contains(sequence, searchSequence)) { error.rejectValue(property, messagePrefix + " should contain sequence \"" + searchSequence + "\""); } }  static void isNotEmpty(String value, String property, String messagePrefix, int length, Errors error); static void isEmpty(String value, String property, String messagePrefix, Errors error); static void isNotLongerThan(String value, String property, String messagePrefix, int length, Errors error); static void isNotEmpty(Collection collection, String property, String errorMessage, Errors error); static void isNotNull(Object value, String property, String messagePrefix, Errors error); static void isNull(Object value, String property, String messagePrefix, Errors error); static void contains(String sequence, String searchSequence, String property, String messagePrefix, Errors error); static void isGreaterThan(Number value, String property, String messagePrefix, Number min, Errors error); static void isGreaterOrEqualTo(Number value, String property, String messagePrefix, Number min, Errors error); static void isBetween(Number value, String property, String messagePrefix, Number min, Number max, Errors error); static void isBetweenInclusive(Number value, String property, String messagePrefix, Number min, Number max, Errors error); static void isNullOrGreaterOrEqualTo(Number value, String property, String messagePrefix, Number min, Errors error); static void isNullOrGreaterThan(Number value, String property, String messagePrefix, Number min, Errors error); static void isDefined(P entity, R repository, String property, String messagePrefix, Errors error); static void isAfter(Date value, String property, String messagePrefix, Date otherDate, Errors error); static boolean isAnId(@Null final String string); static void entityExists(Long id, CrudRepository repository, String property, String messagePrefix, Errors
            error);  }### Answer:
@Test public void shouldContainsNotAcceptNullValue() throws Exception { ValidationUtils.contains(null, "sequence", property, messagePrefix, error); verify(error, times(1)).rejectValue(anyString(), anyString()); }
@Test public void shouldContainsAcceptWhenContainsSequence() throws Exception { ValidationUtils.contains("test_sequence_", "sequence", property, messagePrefix, error); verify(error, times(0)).rejectValue(anyString(), anyString()); }
@Test public void shouldContainsAcceptWhenContainsBashVariableStyleSequence() throws Exception { ValidationUtils.contains("test_${sequence}", "${sequence}", property, messagePrefix, error); verify(error, times(0)).rejectValue(anyString(), anyString()); }
@Test public void shouldContainsNotAcceptWhenMissingSequence() throws Exception { ValidationUtils.contains("", "missing", property, messagePrefix, error); verify(error, times(1)).rejectValue(anyString(), anyString()); }
@Test public void shouldContainsNotAcceptDuoToCaseSensitive() throws Exception { ValidationUtils.contains("sequence", "Sequence", property, messagePrefix, error); verify(error, times(1)).rejectValue(anyString(), anyString()); }