Unit test of VcPlugin issue

[unbreakabl3]

Hello, dear all.
Maybe someone faced such problem.

I have a simple TS function:

/**
 * Checks if a virtual machine with the given name already exists.
 *
 * @param {string} vmName - The name of the virtual machine to check.
 * @returns {string} - An error message if the virtual machine exists, or undefined if it does not.
 */
(function validateVM(vmName: string) {
	const vms: VcVirtualMachine[] = VcPlugin.getAllVirtualMachines(
		null,
		`xpath:name[matches(.,'${vmName}')]`
	);

	if (vms.length > 0) {
		return `Virtual Machine with that name is already exists`;
	}
});

Now, I want to test it. That is the last iteration of trying to mock it. Non one of them didn't work.
PS. I cannot import that TS module, because it's not exported. It is not exported, because it should be converted to proper Action Element with all the inputs etc.

const validateVM = System.getModule("test2.test2.example").validateVM;

describe("validateVM", () => {
	let vm: VcVirtualMachine;
	it("should return an error message if a VM with the same name already exists", () => {
		spyOn(VcPlugin, "getAllVirtualMachines").and.returnValue([vm]);

		const result = validateVM("existingVMName");
		expect(result).toEqual("Virtual Machine with that name is already exists");
	});

	it("should return undefined if no VM with the same name exists", () => {
		spyOn(VcPlugin, "getAllVirtualMachines").and.returnValue([]);

		const result = validateVM("uniqueVMName");
		expect(result).toBeUndefined();
	});
});

So, no matter what I am doing, I am always gettin that:

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] validateVM
[ERROR]   should return an error message if a VM with the same name already exists
[ERROR]     ReferenceError: VcPlugin is not defined

Any ideas now to mock / test VcPlugin or any other similar class?

[unbreakabl3]

Found the solution. Thanks.

[Michaelpalacce]

@unbreakabl3 want to share it for future reference?

[unbreakabl3]

Sure. My bad :)
So, the solution is to add the following into the describe section

beforeEach ( () => {
  (<any> VcPlugin) = {
    getAllVirtualMachines: function () {}
  }
} );

But I am still trying to understand how / why exactly it's doing the job.
@Michaelpalacce , maybe you know? Because I don't see this problem with other classes for example. This was a first time. What is especial in VcPlugin ?