How to use the createStubInstance function from sinon

sinon.createStubInstance is a method in the Sinon library that creates a new object with all of its methods replaced with stub functions.

How does sinon.createStubInstance work?

sinon.createStubInstance is a method in the Sinon library that takes a constructor function as its argument and returns a new object that has all of its methods replaced with stub functions. This can be useful in test scenarios where you need to replace a complex object with a simpler one that behaves in a predictable way. When called, sinon.createStubInstance does the following: Creates a new object using the constructor function passed as an argument. Replaces each method on the object with a stub function using sinon.stub. Returns the new object with its methods stubbed out. Note that sinon.createStubInstance does not execute the constructor function, and therefore does not create any properties on the object that may be initialized by the constructor. It only creates an object with stubbed methods. Overall, sinon.createStubInstance provides an easy way to create objects with simple, predictable behavior for testing purposes.

Ai Example

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const sinon = require("sinon");

class ExampleClass {
  method1() {}
  method2() {}
  method3() {}
}

const stub = sinon.createStubInstance(ExampleClass);

// Invoke stubbed methods on the stub object
stub.method1();
stub.method2();
stub.method3();

// Check if methods were called
sinon.assert.calledOnce(stub.method1);
sinon.assert.calledOnce(stub.method2);
sinon.assert.calledOnce(stub.method3);

In this example, we create a class ExampleClass with three methods. We then create a stubbed instance of this class using sinon.createStubInstance. The resulting stub object has all of its methods replaced with stub functions. We can then invoke the stubbed methods on the stub object as if they were actual methods of ExampleClass. In this case, we call method1, method2, and method3. Finally, we use Sinon's sinon.assert functions to check that each method was called exactly once. By using sinon.createStubInstance, we can easily create stubbed instances of classes for use in unit tests, making it easier to test code that depends on complex objects.