Jest Testing Framework – Adding Multiple Tests

In this section, will see how to add multiple tests and add multiple data sets to validate a function.

In functions.js file

const functions = {
  add: (num1, num2) => {

    if (typeof(num1) !== 'number' || typeof(num2) !== 'number'){
      return null;
    }
    return num1 + num2;
  }
};

module.exports=functions;

In functions.test.js file

const functions=require('./functions');


describe("Addition", () => {
  it("should add two numbers ", () => {
    expect(functions.add(2,2,)).toBe(4);
    expect(functions.add(23,44,)).toBe(67);
    expect(functions.add(15,20,)).not.toBe(25);
    expect(functions.add(-5,5,)).toBe(0);
    expect(functions.add(30,-10,)).toBe(20);
    expect(functions.add(8,0,)).toBe(8);
  });

  it("should not add string ", () => {
    expect(functions.add(2,"2",)).toBe(null);
    expect(functions.add("-10",10,)).toBe(null);
  });

  it("should not add objects ", () => {
    expect(functions.add(20,[],)).toBe(null);
  });

  it("should not add arrays ", () => {
    expect(functions.add(5,{},)).toBe(null);
  });

});

Results:

  PASS  ./functions.test.js
   Addition
     ✓ should add two numbers  (6ms)
     ✓ should not add string  (1ms)
     ✓ should not add objects 
     ✓ should not add arrays  (1ms)
 
 Test Suites: 1 passed, 1 total
 Tests:       4 passed, 4 total
 Snapshots:   0 total
 Time:        1.595s
 Ran all test suites.