Fake difficult-to-build objects with default property values and custom overrides.
// We've all got classes like this, coupled for good reasons, really
// hard to build.
public static class Customer {
public Customer(Long id, String firstName, String lastName, Date dob, Address address, List<Order> orders) {
//
}
public Long id() { return something(); }
public String getFirstName() { return something(); }
public String getLastName() { return something(); }
public int rank() { return something(); }
public Address getAddress() { return something(); }
public List<Order> getOrders() { return something(); }
public void printOn(PrintStream s) { s.println("Hello"); }
public Customer getAffiliate() { return something(); }
}
public static class Address {
public Address(Long id, String line1, String line2, String postcode) {
// ...
}
public Long id() { return something(); }
public String getLine1() { return something(); }
public String getLine2() { return something(); }
public String getPostcode() { return something(); }
}
public static class Order {
public Order(Long id, Customer customer, Address shippedTo, BigDecimal shippingCost, List<OrderItem> items) {
// ...
}
public Long id() { return something(); }
public Customer getCustomer() { return something(); }
public Address getShippedTo() { return something(); }
public BigDecimal getShippingCost() { return something(); }
public OrderStatus getStatus() { return something(); }
public void setStatus(OrderStatus status) {}
}
public static class OrderItem {
public OrderItem(Long id, Order order, Product product, BigDecimal quantity, BigDecimal net, BigDecimal gross, String notes) {
//...
}
//...
}
public abstract class Product {
public Product(Long id, String description, Object ... andSoOnAndSoOn) {}
}
public enum OrderStatus {
PLACED, PICKED, DISPATCHED, RECEIVED, RETURNED
}
// To build a Customer, you need an Address, some Orders, some OrderItems, some Products...
// Fakir to the rescue!
@Test public void fakir_can_build_you_a_customer_in_one_line() {
Customer customer = Faker.fakeA(Customer.class);
assertTrue(customer instanceof Customer);
}
@Test public void it_fakes_string_properties_to_return_their_name() {
Customer customer = Faker.fakeA(Customer.class);
assertEquals("firstName", customer.getFirstName());
assertEquals("lastName", customer.getLastName());
}
@Test public void primitive_properties_have_defaults_too() {
Customer customer = Faker.fakeA(Customer.class);
assertEquals(42, customer.rank());
assertEquals(Long.valueOf(54), customer.id());
}
@Test public void enums_default_to_the_first() {
Order order = Faker.fakeA(Order.class);
assertEquals(OrderStatus.PLACED, order.getStatus());
}
@Test public void you_can_override_properties_with_fields() {
Customer customer = new Faker<Customer>() {
String firstName = "fred";
int rank = 24;
Customer affiliate = null;
}.get();
assertEquals("fred", customer.getFirstName());
assertEquals("lastName", customer.getLastName());
assertEquals(24, customer.rank());
assertNull(customer.getAffiliate());
}
@Test public void and_fake_operations_with_methods() {
Customer customer = new Faker<Customer>() {
void printOn(PrintStream s) {
s.println("kumquat");
}
}.get();
ByteArrayOutputStream os = new ByteArrayOutputStream();
customer.printOn(new PrintStream(os));
assertEquals("kumquat\n", os.toString());
}
@Test public void operations_are_ignored_unless_overridden() {
Order order = Faker.fakeA(Order.class);
order.setStatus(OrderStatus.DISPATCHED);
assertEquals(OrderStatus.PLACED, order.getStatus());
}
@Test public void but_you_can_back_properties_with_fields() {
Order order = new Faker<Order>() {
OrderStatus status = OrderStatus.RECEIVED;
}.get();
assertEquals(OrderStatus.RECEIVED, order.getStatus());
order.setStatus(OrderStatus.RETURNED);
assertEquals(OrderStatus.RETURNED, order.getStatus());
}
@Test public void object_properties_are_faked_recursively_and_cached() {
Customer customer = Faker.fakeA(Customer.class);
Address address = customer.getAddress();
assertEquals("postcode", address.getPostcode());
assertSame(address, customer.getAddress());
assertNotSame(address, Faker.fakeA(Customer.class).getAddress());
}
@Test public void lists_are_faked_with_2_entries() {
Customer customer = Faker.fakeA(Customer.class);
assertEquals(2, customer.getOrders().size());
assertEquals("line1", customer.getOrders().get(1).getShippedTo().getLine1());
}
@Test public void you_can_install_your_own_factory() {
DefaultFactory factory = new DefaultFactory() {
protected BigDecimal createBigDecimal() {
return new BigDecimal("99.99");
}
protected <T> List<T> createList(Class<T> genericType) {
return new FakeList<T>(1, genericType, this);
}
};
Customer customer = Faker.fakeA(Customer.class, factory);
assertEquals(BigDecimal.valueOf(99.99), customer.getOrders().get(0).getShippingCost());
assertEquals(1, customer.getOrders().size());
}
@Test public void and_of_course_combine_that_with_overrides() {
DefaultFactory factory = new DefaultFactory() {
protected BigDecimal createBigDecimal() {
return new BigDecimal("99.99");
}
};
Customer customer = new Faker<Customer>(Customer.class, factory) {
int rank = 101;
}.get();
assertEquals(101, customer.rank());
assertEquals(BigDecimal.valueOf(99.99), customer.getOrders().get(0).getShippingCost());
}
@Test public void you_can_explicitly_return_fakes_from_fakes() {
Customer customer = new Faker<Customer>() {
Address address = new Faker<Address>() {
String line1 = "10 Downing St";
}.get();
}.get();
assertEquals("10 Downing St", customer.getAddress().getLine1());
assertEquals("postcode", customer.getAddress().getPostcode());
}
@Test public void and_if_you_do_you_can_use_the_fields_from_any_old_object() {
Customer customer = new Faker<Customer>() {
Object address = new Object() {
String line1 = "10 Downing St";
};
}.get();
assertEquals("10 Downing St", customer.getAddress().getLine1());
assertEquals("line2", customer.getAddress().getLine2());
}
@Test public void which_leads_to_another_way_of_overriding_at_the_top_level() {
Customer customer = Faker.wrapWith(Customer.class,
new Object() {
String firstName = "fred";
});
assertEquals("fred", customer.getFirstName());
}
@Test public void this_can_be_extended_to_create_spies_on_existing_instances() {
// Feature for next release
// Customer existingCustomer = Faker.fakeA(Customer.class);
//
// Customer customer = Faker.spyOn(existingCustomer,
// new Object() {
// String firstName = "fred";
// });
// assertEquals("fred", customer.getFirstName());
}
public interface CustomerService {
Customer find(Long id);
}
@Test public void and_as_we_lean_so_heavily_on_jmock_we_give_back_an_action() {
Mockery mockery = new Mockery();
final CustomerService customers = mockery.mock(CustomerService.class);
mockery.checking(new Expectations() {{
allowing(customers); will(ReturnAFakeAction.returnAFake());
}});
assertEquals("postcode", customers.find(99L).getAddress().getPostcode());
}Fakir builds and runs under JDK6, but now has some Java8'y goodness for easy testing of legacy code.
@Test public void faker_will_delegate_to_suppliers() {
Customer customer = new Faker<Customer>() {
Supplier<Long> id = () -> Math.round(Long.MAX_VALUE * Math.random());
}.get();
assertNotEquals("OK, it's contrived, but you get the point", customer.id(), customer.id());
}
@Test public void which_can_solve_some_circular_dependency_issues() {
List<Customer> customers = new ArrayList<>(2);
Object[] customerData = {
new Object() {
String lastName = "Flintstone";
Supplier<Customer> affiliate = () -> customers.get(1);
},
new Object() {
Supplier<String> lastName = () -> customers.get(0).getLastName();
}
};
stream(customerData).map(data -> Faker.wrapWith(Customer.class, data)).forEach(customers::add);
assertEquals("Flintstone", customers.get(0).getLastName());
assertEquals("Flintstone", customers.get(1).getLastName());
assertEquals(customers.get(1), customers.get(0).getAffiliate());
assertEquals(customers.get(1), customers.get(0).getAffiliate());
}
@Test
public void you_cant_cast_a_faker_to_a_Java8_supplier() {
try {
Faker<Customer> faker = new Faker<Customer>() {
String firstName = "Fred";
};
Supplier<Customer> java8Supplier = (Supplier<Customer>) faker;
fail("A shame, but nevermind");
} catch (ClassCastException ignored) {
}
}
@Test public void but_you_can_finesse_it() {
Supplier<Customer> java8Supplier = new Faker<Customer>() {
String firstName = "Fred";
}::get;
}
@Test public void and_use_that_to_generalise() {
Supplier<Customer> java8Supplier = asSupplier(new Faker<Customer>() {
String firstName = "Fred";
});
}
private <T> Supplier<T> asSupplier(com.oneeyedmen.fakir.Supplier<T> faker) {
return faker::get;
}