Any file names, that should start with anything but must end with .test.js or .spec.js files are considered as a test file. (or)

All the files within the test folder are considered test files. Note: there are many ways to represent a file as a test file.

Basic example code:

function sortedDataByAge(){
	const obj = [
		{ name: "shivaji", age: 23 },
		{ name: "vyshnavi", age: 21 },
		{ name: "Ravi", age: 50 },
	];
	return obj.sort((a, b) => a.age - b.age);
}

test("Testing the sorted feature", ()=>{
	const sortedDataByAge = sortedDataByAge()
	expect(sortedDataByAge[0].name).toBe("vyshnavi")
})

Methods: toBe() not.toBe(undefined) toBeUndefined(): it passes for an undefined value. not.toBeUndefined(): it fails for an undefined value.

Note: You write a test case but you can't do any Assertions and then your test cases are always passed.

test("Testing the sorted feature", ()=>{
		// No Assertion
})

Automatically Reload: "watch:test" : "jest --watch"

Component Testing: Steps:

• Render.
• Querying.
• Assertion.

create test case: you can create test cases using test or it methods. syntax:

test("test case description", ()=>{
		//test case logic
})
				//OR
it("test case description", ()=>{
		//test case logic
})

describe:

• grouping multiple test cases.
• describe inside another describe also.