Is it possible to simulate or replace a static namespace function call when using Jasmine with Ionic framework?

I am currently navigating through new territory, so I appreciate your patience. My current project involves Ionic 2 using Angular 2, Typescript, and Jasmine for unit testing. At this moment, I am faced with the challenge of writing a unit test for a unique scenario. Within my component, I import a third-party library at the top using 

import * as thirdparty from "thirdparty-library"
. Subsequently, my component utilizes this library with a call like 
thirdparty.setup(someStuff, someMoreStuff, anotherFunc)
.

My ultimate goal is to create a mock version of the thirdparty library that includes its own fabricated version of anotherFunc, which can be passed from within the unit test. Is there a way to achieve this by passing something in the constructor to override the thirdparty namespace? Any insights will be greatly appreciated. Thank you!

angulartypescriptjasmineionic2

Answer №1

In the world of programming, functions are considered first-class citizens, meaning they can be assigned new values. This flexibility allows developers to easily modify function behavior as needed.

let ogFunction;

beforeEach(() => {
  ogFunction = thirdparty.setup;
  thirdparty.setup = (arg1, arg2, arg3) => {
    console.log(`arg1 - arg2 - arg2`)
  }
});

afterEach(() => {
  thirdparty.setup = ogFunction;
});

Sometimes, certain library type definitions may restrict you from assigning new values to a function, rendering it read-only. In such cases, one workaround is to abstract the third-party calls into a service and mock that service instead. This approach not only bypasses the read-only restriction but also promotes better design by decoupling third-party dependencies from the main component.

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