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TestBed.solitary()

Creates a test environment where all dependencies are automatically mocked for testing a class in complete isolation.

Signature​

TestBed.solitary<T>(targetClass: Type<T>): SolitaryTestBedBuilder<T>

Parameters​

ParameterTypeDescription
targetClassType<T>The class constructor to test in isolation

Returns​

Returns a SolitaryTestBedBuilder<TClass> instance with methods for configuring the test environment:

  • .mock(dependency) - Configure specific mock behavior before compilation
  • .compile() - Finalizes configuration and creates the test environment

Description​

TestBed.solitary() creates a test environment where all of the class's dependencies are mocked by default. This is ideal for testing the internal logic of a class in complete isolation.

Suites automatically identifies and mocks all constructor dependencies, which can then be accessed via unitRef.get(). Learn more in the Virtual Test Container guide.

Configuring Mocks​

See Mock Configuration for details on .mock().final() and .mock().impl().

Examples​

Basic Usage​

// All dependencies of UserService are auto-mocked
const { unit, unitRef } = await TestBed.solitary(UserService).compile();

// Retrieve and configure mocks as needed for a test
const userRepository = unitRef.get(UserRepository);
userRepository.findById.mockResolvedValue(testUser);

Token Injections​

// Class with token-injected dependencies
@Injectable()
class PaymentService {
  constructor(
    @Inject('CONNECTION') private connection: Connection,
    @Inject('API_KEY') private apiKey: string
  ) {}
}

const { unitRef } = await TestBed.solitary(PaymentService).compile();

// Retrieve mocks by token
const database = unitRef.get<Connection>('CONNECTION');
const apiKey = unitRef.get<string>('API_KEY');

Type Safety​

All retrieved mocks are fully type-safe, providing autocompletion and compile-time checks.

const repository = unitRef.get(UserRepository);

// ✅ TypeScript knows all methods
repository.findById.mockResolvedValue(user);

// ❌ Compile error: method doesn't exist
repository.invalidMethod.mockReturnValue(123);

See Also​