### Question:
ParameterHelper implements JournalConstants { public static String parseParametersForFilenamePrefix(Map<String, String> parameters) { return getOptionalStringParameter(parameters, PARAMETER_JOURNAL_FILENAME_PREFIX, DEFAULT_FILENAME_PREFIX); } private  ParameterHelper(); static String getOptionalStringParameter(Map<String, String> parameters,
                                                    String parameterName,
                                                    String defaultValue); static boolean getOptionalBooleanParameter(Map<String, String> parameters,
                                                      String parameterName,
                                                      boolean defaultValue); static File parseParametersForWritableDirectory(Map<String, String> parameters,
                                                           String parameterName); static String parseParametersForFilenamePrefix(Map<String, String> parameters); static long parseParametersForSizeLimit(Map<String, String> parameters); static long parseParametersForAgeLimit(Map<String, String> parameters);  }### Answer:
@Test public void testParseParametersForFilenamePrefix_Value() { parameters.put(PARAMETER_JOURNAL_FILENAME_PREFIX, "somePrefix"); String result = ParameterHelper.parseParametersForFilenamePrefix(parameters); assertEquals("somePrefix", result); }
@Test public void testParseParametersForFilenamePrefix_Default() { String result = ParameterHelper.parseParametersForFilenamePrefix(parameters); assertEquals(DEFAULT_FILENAME_PREFIX, result); }