### Question:
AAIVpnBindingResources { public boolean existsCustomer(Customer customer) { AAIResourceUri uriCustomer = AAIUriFactory .createResourceUri(AAIFluentTypeBuilder.business().customer(customer.getGlobalCustomerId())); return injectionHelper.getAaiClient().exists(uriCustomer); }  boolean existsCustomer(Customer customer); Optional<VpnBindings> getVpnBindingByCustomerVpnId(String customerVpnId); void createVpnBinding(VpnBinding vpnBinding); void createCustomer(Customer customer); Optional<org.onap.aai.domain.yang.VpnBinding> getVpnBinding(String vpnId); void connectCustomerToVpnBinding(String globalSubscriberId, String vpnId);  }### Answer:
@Test public void existsCustomerTest() { when(MOCK_aaiResourcesClient.exists(isA(AAIResourceUri.class))).thenReturn(true); boolean isCustomerExist = aaiVpnBindingResources.existsCustomer(customer); verify(MOCK_aaiResourcesClient, times(1)).exists(isA(AAIResourceUri.class)); assertEquals(true, isCustomerExist); }