CachingKeyProvider extends
    KeyProviderExtension<CachingKeyProvider.CacheExtension> { @Override public KeyVersion getKeyVersion(String versionName) throws IOException { try { return getExtension().keyVersionCache.get(versionName); } catch (ExecutionException ex) { Throwable cause = ex.getCause(); if (cause instanceof KeyNotFoundException) { return null; } else if (cause instanceof IOException) { throw (IOException) cause; } else { throw new IOException(cause); } } } CachingKeyProvider(KeyProvider keyProvider, long keyTimeoutMillis,
      long currKeyTimeoutMillis); @Override KeyVersion getCurrentKey(String name); @Override KeyVersion getKeyVersion(String versionName); @Override void deleteKey(String name); @Override KeyVersion rollNewVersion(String name, byte[] material); @Override KeyVersion rollNewVersion(String name); @Override void invalidateCache(String name); @Override Metadata getMetadata(String name);  }
@Test public void testKeyVersion() throws Exception { KeyProvider.KeyVersion mockKey = Mockito.mock(KeyProvider.KeyVersion.class); KeyProvider mockProv = Mockito.mock(KeyProvider.class); Mockito.when(mockProv.getKeyVersion(Mockito.eq("k1@0"))) .thenReturn(mockKey); Mockito.when(mockProv.getKeyVersion(Mockito.eq("k2@0"))).thenReturn(null); Mockito.when(mockProv.getConf()).thenReturn(new Configuration()); KeyProvider cache = new CachingKeyProvider(mockProv, 100, 100); Assert.assertEquals(mockKey, cache.getKeyVersion("k1@0")); Mockito.verify(mockProv, Mockito.times(1)) .getKeyVersion(Mockito.eq("k1@0")); Assert.assertEquals(mockKey, cache.getKeyVersion("k1@0")); Mockito.verify(mockProv, Mockito.times(1)) .getKeyVersion(Mockito.eq("k1@0")); Thread.sleep(200); Assert.assertEquals(mockKey, cache.getKeyVersion("k1@0")); Mockito.verify(mockProv, Mockito.times(2)) .getKeyVersion(Mockito.eq("k1@0")); cache = new CachingKeyProvider(mockProv, 100, 100); Assert.assertEquals(null, cache.getKeyVersion("k2@0")); Mockito.verify(mockProv, Mockito.times(1)) .getKeyVersion(Mockito.eq("k2@0")); Assert.assertEquals(null, cache.getKeyVersion("k2@0")); Mockito.verify(mockProv, Mockito.times(2)) .getKeyVersion(Mockito.eq("k2@0")); }