grommett/spy-lite

Spy Lite

  

Why?

I love Sinon, and I know there are a million other spy libraries out there, but I wanted to make my own.
For the fun of it.

Using It

Spy Lite has one method: calledWith and three properties: called, callCount, args.

called

The property called returns a boolean:

const testSpy1 = spy();
const testSpy2 = spy();

testSpy1();

console.log(testSpy1.called); // true
console.log(testSpy2.called); // false

callCount

The property callCount returns a number representing the amount of times the spy has been called:

const testSpy = spy();

testSpy1();
console.log(testSpy.callCount); // 1

testSpy1();
console.log(testSpy.callCount); // 2

args

The property args returns an array, which accumulates on each spy call.
Each entry in the args array is another array representing the values used each time the spy has been called.

const testSpy = spy();

testSpy1(1);
console.log(testSpy.args); // [ [1] ]

testSpy1(1,2);
console.log(testSpy.args); // [ [1], [1, 2] ]

// Get arguments from first call
console.log(testSpy.args[0]); // [1]

// Get arguments from second call
console.log(testSpy.args[1]); // [1, 2]

calledWith

The method calledWith returns a boolean and works with string, number, array and object. Since calledWith compares against the args property it will return true if it finds the test value in any of the spy's calls.

const testSpy = spy();

testSpy(1, 2);

console.log(testSpy.calledWith(1)) // true;
console.log(testSpy.calledWith(2)) // true;
console.log(testSpy.calledWith(3)) // false;

// ..later
testSpy([1, 2]);
console.log(testSpy.calledWith([1,2])) // true;
console.log(testSpy.calledWith(2)) // true;