### Question:
OrganizationFactory { public ServiceClient makeServiceClient(String serviceId) { if (serviceId == null) throw new IllegalArgumentException("Argument serviceId cannot be null"); UUID serviceUUID = UUID.fromString(serviceId); return new BasicServiceClient(serviceUUID, transport); } OrganizationFactory(Transport transport, UUID organizationId); DirectoryClient makeDirectoryClient(String directoryId); ServiceClient makeServiceClient(String serviceId); OrganizationClient makeOrganizationClient();  }### Answer:
@Test(expected = IllegalArgumentException.class) public void testMakeServiceClientWithNullThrowsIllegalArgument() throws Exception { organizationFactory.makeServiceClient(null); }
@Test(expected = IllegalArgumentException.class) public void testMakeServiceClientWithInvalidUUIDThrowsIllegalArgument() throws Exception { organizationFactory.makeServiceClient("Not A UUID"); }
@Test public void testMakeServiceClientWithValidUUIDReturnsClient() throws Exception { assertThat(organizationFactory.makeServiceClient("49af9c38-31b3-11e7-93ae-92361f002671"), instanceOf(ServiceClient.class)); }