@SuppressWarnings("ConstantConditions")
@Test
public void getBalance_NullInput_IllegalArgumentException() throws Exception {

    mockWebServer.enqueue(new MockResponse()
            .setResponseCode(500)
    );
    expectedEx.expect(IllegalArgumentException.class);
    AccountInfoRetriever accountInfoRetriever = new AccountInfoRetriever(server);
    accountInfoRetriever.getBalance(null);
}