### Question:
NamePatternIdprovider { public String getProviderId() { return providerId; } NamePatternIdprovider(String providerId); void add(NamePatternToIdEntry entry); String getIdForName(String name); String getProviderId(); @Override String toString();  }### Answer:
@Test public void providerId_is_returned_and_null_is_allowed_too() { assertEquals("testid",new NamePatternIdprovider("testid").getProviderId()); assertEquals(null, new NamePatternIdprovider(null).getProviderId()); }