Testing Batch Processes - Spring Batch - page 450

methods. The first one, which tests when no customers are returned from the delegate, is very easy; see
Listing 12-6.
Listing 12-6. testReadNoCustomers()
…
@Test
public void testReadNoCustomers() throws Exception {
assertNull(reader.read());
}
…
Wait, that's it? What happened? There is a lot more happening under the covers of this extremely
simple test method than meets the eye. When you execute this method, CustomerStatementReader 's read
method is called. In there, Mockito returns null when the mock ItemReader's read method is called on
line 40. By default, if you don't tell Mockito what to return when a method is called on a mock object, it
returns a type-appropriate value ( null for objects, false for boolean s, -1 for int s, and so on). Because
you want your mock object to return null for this test, you don't need to tell Mockito to do anything for
you. Aftre Mockito returns null from the ItemReader you injected, the logic returns null as required.
Your test verifies that the reader returns null with JUnit's Assert.assertNull method.
The second test method you need to write for the read method of CustomerStatementReader tests
that the Statement object is being built correctly when a customer is returned. In this scenario, because
you aren't working with a database, you need to tell Mockito what to return when
tickerDao.getTotalValueForCustomer and tickerDao.getStocksForCustomer are called with the
customer's id. Listing 12-7 shows the code for the testReadWithCustomer method.
Listing 12-7. testReadWtihCustomer
…
@SuppressWarnings("serial")
@Test
public void testReadWithCustomer() throws Exception {
Customer customer = new Customer();
customer.setId(5l);
when(customerReader.read()).thenReturn(customer);
when(tickerDao.getTotalValueForCustomer(5l)).thenReturn(
new BigDecimal("500.00"));
when(tickerDao.getStocksForCustomer(5l)).thenReturn(
new ArrayList<Transaction>() {
{
add(new Transaction());
}
});
Statement result = reader.read();
assertEquals(customer, result.getCustomer());
assertEquals(500.00, result.getSecurityTotal().doubleValue(), 0);
assertEquals(1, result.getStocks().size());
}
…