System.builder()

Integration tests using the Pixie System

For integration-style tests that exercise the full Pixie wiring — component resolution, event dispatch, and the complete object graph — use System.builder().

Basic Wiring Test

@Test
public void testFullSystem() {
    final System system = System.builder()
            .definition(Person.class, "jane")
            .param("age", 37)
            .comp("address", "home")

            .definition(Address.class, "home")
            .param("street", "820 Roosevelt Street")
            .param("city", "River Falls")
            .param("state", "WI")
            .param("zipcode", "54022")

            .build();

    final Person jane = system.get(Person.class);

    assertEquals("jane", jane.getName());
    assertEquals(37, jane.getAge());
    assertEquals("River Falls", jane.getAddress().getCity());
}

Testing Event Wiring

System.builder() wires @Event consumers and @Observes methods together automatically. This lets you verify that firing an event in one component reaches observers in another:

@Test
public void testEventFlow() {
    final System system = System.builder()
            .definition(ShoppingCart.class)
            .definition(EmailReceipt.class)
            .definition(LogOrder.class)
            .build();

    final ShoppingCart cart = system.get(ShoppingCart.class);
    final EmailReceipt email = system.get(EmailReceipt.class);
    final LogOrder log = system.get(LogOrder.class);

    cart.order("order-101");

    assertEquals(1, email.getOrdersProcessed().size());
    assertEquals("order-101", email.getOrdersProcessed().get(0).getId());

    assertEquals(1, log.getOrdersProcessed().size());
    assertEquals("order-101", log.getOrdersProcessed().get(0).getId());
}

Injecting Test Doubles

Use system.add() to substitute pre-built instances — mocks, stubs, or test-specific implementations — into the object graph:

@Test
public void testWithMockProcessor() {
    final List<String> charged = new ArrayList<>();

    final System system = System.builder()
            .add("stripe", (PaymentProcessor) charged::add)

            .definition(ShoppingCart.class, "cart")

            .build();

    final ShoppingCart cart = system.get(ShoppingCart.class);
    cart.order("order-101");

    assertEquals(1, charged.size());
}

The @Component reference to stripe resolves to the lambda you provided. The component under test doesn’t know or care that it’s a test double.

Mixing Approaches

Plain Java tests and System.builder() tests serve different purposes:

Approach	Best For
Plain Java	Unit testing a single class in isolation. Fast, no framework overhead.
System.builder()	Integration testing the wired object graph. Verifies resolution, events, and component interaction.

Use both. Plain Java tests verify your logic. System.builder() tests verify your wiring.