### Question:
FieldValuePrefixAdder { public String extractFieldValue(String valueWithPrefix) { Preconditions.checkNotNull(valueWithPrefix); return valueWithPrefix.split(FIELD_VALUE_PREFIX_SEPARATOR)[1]; }  String addFieldPrefix(String prefix, String fieldValue); String prefixWithSeparator(String fieldValuePrefix); String extractFieldValue(String valueWithPrefix);  }### Answer:
@Test(expected = NullPointerException.class) public void extractFieldValue_Null() { fieldValuePrefixAdder.extractFieldValue(null); }
@Test public void extractFieldValue() { assertEquals("value", fieldValuePrefixAdder.extractFieldValue("prefix"+FIELD_VALUE_PREFIX_SEPARATOR+"value")); }