Common Terminologies of Jest

Describe Blocks

A describe block is used for organizing test cases in logical groups of tests. For example, we want to group all the tests for a specific class.

describe('Your describe block logical name', () => {
   /**Test cases comes under describe block**/
});

"it" or "test" Tests

we use the test keyword to start a new test case definition. The it keyword is an alias for the test keyword. Personally, I like to use test, which allows for more natural language flow of writing tests.

it('your test logical name comes here', () => {
    /** test case logic***/
});

test('your test logical name comes here', () => {
    /** test case logic***/
});

Matchers

A matcher is used for creating assertions in combination with the expect keyword. We want to compare the output of our test with a value we expect the function to return.

test('sum of two number', () => {
    expect(2+2).toBe(4)
});

expect function is used everytime you want to test a value.you will use expect along with a "matcher" function to assert something about value

The complete list of exposed matchers can be found in the https://jestjs.io/docs/en/expect.html#tobevalue.

beforeEach

If you have some work you need to do repeatedly for many tests, you can use beforeEach block. This blocks Runs a function before each of the tests in this file runs

beforeEach(() => {
  /** logic will go here**/
});

beforeEach

If you have some work you need to do repeatedly for many tests, you can use afterEach block. This blocks Runs a function after each of the tests in this file runs

afterEach(() => {
  /** logic will go here**/
});