Example
Jasmine can spy on an existing function using the spyOn function.
let calculator = {
multiply: function(a, b) {
return a * b;
},
square: function(a) {
return this.multiply(a, a);
}
}
describe('calculator', function() {
it('squares numbers by multiplying them by themselves', function() {
let num = 2;
spyOn(calculator, 'multiply');
calculator.square(NUM);
expect(calculator.multiply).toHaveBeenCalledWith(NUM, NUM);
})
});
After the function has been spied on it is replaced with a spy, that can be queried for information about how and when it has been called.
