TestBed.sociable()

Test business logic interactions with real and mocked dependencies

Creates a test environment that mixes real implementations with mocked dependencies for testing interactions between business logic classes.

Signature

TestBed.sociable<T>(targetClass: Type<T>): SociableTestBuilder<T>

Parameters

Parameter	Type	Description
targetClass	`Type<T>`	The class constructor to test

Returns

SociableTestBuilder<T> with the following configuration method:

.expose() - List classes to keep real. Everything else is mocked.
.mock(dependency) - Configure specific mock behavior before compilation
.compile() - Finalizes configuration and creates the test environment

The `.expose()` Method

expose<D>(dependency: Type<D>): SociableTestBuilder<T>

.expose() only accepts class constructors, not tokens. Tokens represent abstractions (interfaces, types) following the Dependency Inversion Principle - there is no concrete implementation to “expose”. Additionally, tokens typically represent external I/O (databases, HTTP clients) and are always mocked to keep sociable tests fast and side-effect-free.
.expose() method only controls explicit, injected dependencies. Implicit dependencies (direct imports) are not intercepted by TestBed and will execute as normal.

Example

const { unit, unitRef } = await TestBed.sociable(UserService)
  .expose(UserValidator)  // Only this is real
  .compile();

// Can retrieve non-exposed (mocked)
const database = unitRef.get(Database);

// Cannot retrieve exposed
// const validator = unitRef.get(UserValidator);  // ERROR - it's real

What’s Retrievable

With .expose():

✅ Non-exposed dependencies (mocked by default)
✅ Tokens (auto-mocked)
✅ Explicitly mocked dependencies
❌ Exposed dependencies (real, not retrievable)