ThreadContext { public static String get(final String key) { return provider.get(key); } private  ThreadContext(); static Map<String, String> getMapping(); static String get(final String key); static void put(final String key, final Object value); static void remove(final String key); static void clear();  }
@Test public void getExistingValue() { when(provider.get("pi")).thenReturn("3.14"); assertThat(ThreadContext.get("pi")).isEqualTo("3.14"); }
@Test public void getMissingValue() { assertThat(ThreadContext.get("pi")).isNull(); }