### Question:
LruMemoryStore extends AbstractStore { public final boolean containsKey(Object key) { return map.containsKey(key); } LruMemoryStore(Ehcache cache, Store diskStore); synchronized void unpinAll(); synchronized boolean isPinned(Object key); synchronized void setPinned(Object key, boolean pinned); final boolean put(Element element); final boolean putWithWriter(Element element, CacheWriterManager writerManager); final synchronized Element get(Object key); final synchronized Element getQuiet(Object key); final Element remove(Object key); final Element removeWithWriter(Object key, CacheWriterManager writerManager); final synchronized void removeAll(); final synchronized void dispose(); final void flush(); final Status getStatus(); final synchronized List getKeys(); final int getSize(); final int getTerracottaClusteredSize(); final boolean containsKey(Object key); final synchronized long getSizeInBytes(); void expireElements(); boolean bufferFull(); Object getMBean(); Policy getEvictionPolicy(); void setEvictionPolicy(Policy policy); Object getInternalContext(); boolean containsKeyInMemory(Object key); boolean containsKeyOffHeap(Object key); boolean containsKeyOnDisk(Object key); Policy getInMemoryEvictionPolicy(); int getInMemorySize(); long getInMemorySizeInBytes(); int getOffHeapSize(); long getOffHeapSizeInBytes(); int getOnDiskSize(); long getOnDiskSizeInBytes(); void setInMemoryEvictionPolicy(Policy policy); Element putIfAbsent(Element element); Element removeElement(Element element, ElementValueComparator comparator); boolean replace(Element old, Element element, ElementValueComparator comparator); Element replace(Element element);  }### Answer:
@Test public void testContainsKey() { final Object key = new Object(); assertThat(store.containsKey(key), is(false)); store.setPinned(key, true); assertThat(store.get(key), nullValue()); assertThat(store.containsKey(key), is(false)); }