Startup.cs

using EmployeeManagement.Models;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc.Authorization;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;

namespace EmployeeManagement
{
    public class Startup
    {
        private IConfiguration _config;

        public Startup(IConfiguration config)
        {
            _config = config;
        }

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContextPool<AppDbContext>(
                options => options.UseSqlServer(_config.GetConnectionString("EmployeeDBConnection")));

            services.AddIdentity<ApplicationUser, IdentityRole>(options =>
            {
                options.Password.RequiredLength = 6;
                options.Password.RequireNonAlphanumeric = false;
                options.Password.RequireLowercase = false;
                options.Password.RequireUppercase = false;
            }).AddEntityFrameworkStores<AppDbContext>();

            services.AddMvc(options=>{
                var policy = new AuthorizationPolicyBuilder()
                             .RequireAuthenticatedUser()
                             .Build();
                options.Filters.Add(new AuthorizeFilter(policy));
            });

            services.AddAuthorization(options=>
            {
                options.AddPolicy("DeleteRolePolicy",
                    policy => policy.RequireClaim("Delete Role"));

                options.AddPolicy("EditRolePolicy",
                    policy => policy.RequireClaim("Edit Role"));

                options.AddPolicy("AdminRolePolicy",
                    policy => policy.RequireClaim("Admin"));

            });
            //services.AddSingleton<IEmployeeRepository, MockEmployeeRepository>();
            services.AddScoped<IEmployeeRepository, SQLEmployeeRepository>();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }else
            {
                app.UseExceptionHandler("/Error");
                app.UseStatusCodePagesWithReExecute("/Error/{0}");
            }

            app.UseStaticFiles();
            app.UseAuthentication();
            //conventional routing:
            app.UseMvc(routes =>
            {
                routes.MapRoute("default", "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}