Mock target class

task.ts

import * as tl from 'azure-pipelines-task-lib';
import * as wa from "azure-devops-node-api/WebApi";
import * as GitInterfaces from "azure-devops-node-api/interfaces/GitInterfaces";
import VariableResolver from './variableresolver';
import { IGitApi, GitApi } from 'azure-devops-node-api/GitApi';

export interface IClientFactory {
    create(pat:string): Promise<IGitApi>;
}

class ClientFactory implements IClientFactory {
    public async create(pat:string): Promise<IGitApi> {
        let credHandler = wa.getPersonalAccessTokenHandler(pat);
        let connection = new wa.WebApi(tl.getVariable('System.TeamFoundationCollectionUri'), credHandler);
        return await connection.getGitApi();
    }
}

export class CreatePRCommentTask {
    factory: IClientFactory;

    constructor(clientFactory: IClientFactory) {
        this.factory = clientFactory;
    }
    
    : 
    

new CreatePRCommentTask(new ClientFactory()).run();