@Test
  public void testContainsKey() throws CacheException {
    String key = getUniqueName();
    Region<Object, Object> region = createRegion(key);
    Object value = 42;

    assertFalse(region.containsKey(key));
    region.create(key, null);
    assertFalse(region.containsValueForKey(key));

    Region.Entry entry = region.getEntry(key);
    assertNotNull(entry);
    assertEquals(entry.getKey(), key);
    assertNull(entry.getValue());

    region.put(key, value);
    assertTrue(region.containsValueForKey(key));
    assertEquals(entry, region.getEntry(key));
    if (entry.isLocal()) {
      assertEquals(value, entry.getValue());
    } else {
      assertEquals(value, region.getEntry(key).getValue());
    }
  }
Tests that creating an entry in a region actually creates it

@see Region#containsKey
@see Region#containsValueForKey
geode-dunit/src/main/java/org/apache/geode/cache30/RegionTestCase.java