How do I spyOn Typescript getters and setters?

Question

When I unit test my getters are setters for Typescript, I cannot find a way to spy on those getters and setters. Instead, the object immediately gets evaluated. I am using Jasmine to unit test.

Duplicate of https://stackoverflow.com/questions/20879990 – goWithSwagger Oct 17 '17 at 13:21 — goWithSwagger, Oct 17 '17 at 13:21

score 29 · Answer 1 · answered Jun 03 '17 at 15:02

29

spyOnProperty is now available in Jasmine:

const foop = {
    get value() {},
    set value(v) {}
};

it('can spy on getter', () => {
    spyOnProperty(foop, 'value', 'get').and.returnValue(1);
    expect(foop.value).toBe(1);
});

it('and on setters', () => {
    const spiez = spyOnProperty(foop, 'value', 'set');
    foop.value = true;
    expect(spiez).toHaveBeenCalled();
});

answered Jun 03 '17 at 15:02

Laoujin

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I am trying this, spyOnProperty(component, 'name', 'get').and.returnValue(1); expect(component.name).toBe(1); But it keeps throwing the error: component.name is not a function – cheesydoritosandkale Jun 12 '20 at 13:31
If the above code doesn't work, try upgrading Jasmine? – Laoujin Jun 12 '20 at 13:51

score 3 · Accepted Answer · answered Nov 07 '15 at 10:58

It is not supported yet, but there is a Jasmine issue for supporting getters.

If you really need the support now, you can extend SpyRegistry.js file and add the code that apsillers proposed:

this.spyOnProperty = function(obj, methodName, accessType) {
    ...
    var desc = Object.getPropertyDescriptor(obj, methodName);
    if(desc[accessType]) { // "get" or "set" exists on the property
        var spy = j$.createSpy(methodName, desc[accessType]);  

        desc[accessType] = spy;

        Object.defineProperty(obj, methodName, desc);
    }
}

score 2 · Answer 3 · answered Nov 06 '15 at 22:44

2

I cannot find a way to spy on those getters and setters. Instead, the object immediately gets evaluated.

That is not supported by Jasmine. Your primary options are to refactor into function calls OR extend jasmine

answered Nov 06 '15 at 22:44

basarat

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1

I believe it still is not, in 2020. Running into test framework limitations like this is... basically just embarrassing :/ – Michahell Jun 10 '20 at 09:03

score 0 · Answer 4 · answered Jun 21 '17 at 22:49

0

I found the solution here helpful. Instead of spying on the getter, just overriding it to modify the return for testing.

https://stackoverflow.com/a/26888312/1341825

answered Jun 21 '17 at 22:49

theUtherSide

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How do I spyOn Typescript getters and setters?

4 Answers4

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