### Question:
AMKeyProvider implements KeyProvider { public java.security.PrivateKey getPrivateKey(String certAlias) { java.security.PrivateKey key = null; try { key = (PrivateKey) ks.getKey(certAlias, privateKeyPass.toCharArray()); } catch (KeyStoreException e) { logger.error(e.getMessage()); } catch (NoSuchAlgorithmException e) { logger.error(e.getMessage()); } catch (UnrecoverableKeyException e) { logger.error(e.getMessage()); } return key; } AMKeyProvider();  AMKeyProvider(
            String keyStoreFilePropName, String keyStorePassFilePropName,
            String keyStoreTypePropName, String privateKeyPassFilePropName);  AMKeyProvider(boolean alreadyResolved,
            String keyStoreFile, String keyStorePass,
            String keyStoreType, String privateKeyPass); static String decodePassword(String password); void setLogger(Debug logger); void setKey(String storepass, String keypass); java.security.cert.X509Certificate getX509Certificate(
            String certAlias); java.security.PublicKey getPublicKey(String keyAlias); java.security.PrivateKey getPrivateKey(String certAlias); @Override SecretKey getSecretKey(String certAlias); PrivateKey getPrivateKey(String certAlias, String encryptedKeyPass); KeyPair getKeyPair(String certAlias); String getCertificateAlias(Certificate cert); char[] getKeystorePass(); String getPrivateKeyPass(); String getKeystoreType(); String getKeystoreFilePath(); KeyStore getKeyStore(); void setCertificateEntry(String certAlias, Certificate cert); Certificate getCertificate(String certAlias); void store(); Certificate getCertificate(
            java.security.PublicKey publicKey); @Override boolean containsKey(String alias);  }### Answer:
@Test public void getDefaultPrivateKeyUsingDefaultPassword() { PrivateKey key = amKeyProvider.getPrivateKey(DEFAULT_PRIVATE_KEY_ALIAS); Assert.assertNotNull(key); }
@Test public void getPrivateKeyUsingProvidedPassword() { String encodedPrivatePass = AccessController.doPrivileged(new EncodeAction(PRIVATE_KEY_PASS)); PrivateKey key = amKeyProvider.getPrivateKey(PRIVATE_KEY_ALIAS, encodedPrivatePass); Assert.assertNotNull(key); }
@Test public void getPrivateKeyUsingNullPassword() { PrivateKey key = amKeyProvider.getPrivateKey(PRIVATE_KEY_ALIAS, null); Assert.assertNull(key); }
@Test public void getPrivateKeyUsingDefaultPassword() { PrivateKey key = amKeyProvider.getPrivateKey(PRIVATE_KEY_ALIAS); Assert.assertNull(key); }