Why is TypeScript beneficial for writing unit tests?
It improves runtime performance of tests.
It ensures type safety and catches errors during compilation.
It eliminates the need for assertions in test cases.
It allows tests to run without a testing framework.
Which of the following is a correct TypeScript test case?
TypeScript
import { add } from "./math";
test("should add two numbers", () => {
const result: number = add(2, 3);
expect(result).toBe(5);
});
TypeScript does not support the test function.
The type of result must not be explicitly declared.
This is a correct TypeScript test case using a testing framework.
TypeScript tests must use the assert method instead of expect.
Which testing framework is commonly used with TypeScript?
How do you configure Jest to work with TypeScript?
Use the ts-jest package and update the Jest configuration file
Install typescript-jest and run jest --ts command.
Replace all .ts files with .js for testing.
Jest does not support TypeScript.
What is type-safe mocking?
A process to mock runtime behaviors without using type definitions.
Creating mock implementations that adhere to the original type or interface.
Using only default exports for mock functions.
Replacing the actual implementation with an empty function.
Which library helps create type-safe mocks in TypeScript?
How would you create a type-safe mock using Jest?
TypeScript
interface UserService {
getUser: (id: number) => string;
}
const mockUserService: jest.Mocked<UserService> = {
getUser: jest.fn().mockReturnValue("Pranjal"),
};
Jest does not support type-safe mocking.
Use the jest.Mocked<T> utility for type-safe mocks.
Create mocks by directly implementing the interface.
Mocks do not require adherence to type definitions.
Why is mocking important in unit tests?
To avoid testing external dependencies and isolate the system under test.
To replace all type checks with assertions.
To test multiple systems simultaneously.
To reduce the need for test cases.
Which of the following is a valid use case for a test double?
To represent a function or object being replaced in a test.
To replace TypeScript’s type system with mocks.
To execute real implementations during testing.
To write tests without a testing framework.
What does the following mock do?
TypeScript
jest.spyOn(console, "log").mockImplementation(() => {});
Logs all console messages to the test output.
Replaces the console.log function with a mocked implementation.
Prevents console messages from being logged.
Deletes the console.log method entirely.
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