What is the difference between describe() and it() in spec.js file in protractor?

Question

When writing the test case in spec.js file in protractor then 2 fields are showing describe() and it(). what exactly the use of them and when to use?

// spec.js

describe('Protractor Demo App', function() {
  it('should have a title', function() {
    ..
  });
});

Answer 1

By reading this hopefully you will come to know your answer.

spec.js about (how Jasmine a behavior-driven development framework for testing JavaScript code works)

It has two main functions

Suite describe Your Tests

A test suite begins with a call to the global Jasmine function describe with two parameters: a string and a function. The string is a name or title for a spec suite - usually what is being tested. The function is a block of code that implements the suite.

Specs

Specs are defined by calling the global Jasmine function it, which, like describe takes a string and a function. The string is the title of the spec and the function is the spec, or test. A spec contains one or more expectations that test the state of the code. An expectation in Jasmine is an assertion that is either true or false. A spec with all true expectations is a passing spec. A spec with one or more false expectations is a failing spec.

describe("A suite", function() {
  it("contains spec with an expectation", function() {
     expect(true).toBe(true);
  });
});

It's Just Functions

Since describe and it blocks are functions, they can contain any executable code necessary to implement the test. JavaScript scoping rules apply, so variables declared in a describe are available to any it block inside the suite.

For more details, you can see this link

Answer 2

it is an actual test with logic. describe is a container for tests which allows you to divide tests into multiple parts. describe blocks can wrap tests that act on the same part of an application or have something in common, for example:

describe('Menu tests', function() {
    it('should open menu', function() {
    });
    it('should select menu', function() {
    });
    it('should close menu', function() {
    });
});

describe exposes a couple of functions, such us:

• beforeAll - runs before first test.
• beforeEach - runs before each test.

And many more.

it cannot or at least shouldn't contain describe or it blocks inside itself, whereas describe is supposed to contain it blocks as well as helper blocks (e.g. beforeAll).