Unit Testing

Preview — 3 of 10 questions

What best describes unit testing?

javascript

// Function to test
function add(a, b) {
  return a + b;
}

// Unit test
test("add function should return sum of two numbers", () => {
  expect(add(2, 3)).toBe(5);
  expect(add(-1, 1)).toBe(0);
  expect(add(0, 0)).toBe(0);
});

ATesting an entire application end-to-end.

BTesting individual units/functions in isolation to verify they work correctly.

CTesting only the user interface.

DTesting code only in production.

Which of the following is a JavaScript test framework?

javascript

// test.js
describe("Math operations", () => {
  test("should add two numbers", () => {
    expect(2 + 2).toBe(4);
  });
});

AReact

BNode.js

CExpress

DJest

What is an assertion in testing?

javascript

expect(value).toBe(expectedValue);        // Strict equality
expect(value).toEqual(expectedValue);     // Deep equality
expect(value).toBeTruthy();               // Is truthy
expect(value).toBeFalsy();                // Is falsy
expect(array).toContain(item);            // Array contains item
expect(function).toThrow();               // Function throws error
expect(number).toBeGreaterThan(5);        // Greater than

AA statement that verifies a value is what you expect it to be.

BA statement that declares what a variable should be.

CAn error message.

DA test file.

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