I am running into an issue while writing unit test to test a function that has instance check. Business logic:
let status = new B();
const testFunction = () => {
if (status instanceof A) {
console.log('inside A')
} else if (status instanceof B) {
console.log('inside B')
} else {
console.log('No matchers')
}
}
Unit Test:
describe('test', ()=>{
it("should test b", ()=>{
let status = new A()
expect(status).toBeInstanceOf(A) // passes
expect(logSpy).toHaveBeenCalledWith('inside A') // fails and it expects 'inside B'
})
})
One reason I feel the test is failing is because in the original file, status is return an instance of class B, so it matches else if and not if. I am not sure how to test this code without change status? Is there a way that I am missing out?
EDIT: Here the assumption is that the testFunction() is already invoked in unit tests
You can pass the status as parameter of your function;
const testFunction = (status) => {
if (status instanceof A) {
console.log('inside A')
} else if (status instanceof B) {
console.log('inside B')
} else {
console.log('No matchers')
}
}
Then testFunction() should be called with the status that you need to test;
const status = new A();
testFunction(status);
The problem with your test is that the function that your are testing has its own scope, the other solution is to mock the variable, but could be most confused