如何测试我的模型是否已更改并需要迁移？答案

【问题标题】：How can I test if my model has changed and requires a migration?如何测试我的模型是否已更改并需要迁移？
【发布时间】：2022-03-11 18:10:08
【问题描述】：

在开发 dot net 应用程序时，我们会定期对模型进行更改，并且可能让我们的单元测试仅在内存中运行、动态创建的数据库。

一切都可以正常工作，一切都很好，然后我们部署，突然一切停止工作，因为我们忘记了我们需要迁移数据库。

如果模型已更改但它没有针对该更改的迁移，我如何编写将失败的单元测试？

【问题讨论】：

标签： .net-core entity-framework-core

【解决方案1】：

像这样

using MyProject.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Design;
using Microsoft.EntityFrameworkCore.Migrations.Design;
using Microsoft.Extensions.DependencyInjection;
using Shouldly;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using Xunit;

namespace MyProject.Tests.Migrations
{
    public class MissingMigrationsTest : MyProjectTestBase
    {
        /// <summary>
        /// Sometimes we change the model, but forget to create a migration for it (with dotnet ef migrations add)
        /// We do this test to detect a missing migration.
        /// </summary>
        /// <returns></returns>
        [Fact]
        public async Task ShouldCreateABlankMigration()
        {
            var db = new MyProjectDbContextFactory();

            // Create design-time services
            var serviceCollection = new ServiceCollection();
            serviceCollection.AddEntityFrameworkDesignTimeServices();
            serviceCollection.AddDbContextDesignTimeServices(db);
            var serviceProvider = serviceCollection.BuildServiceProvider();

            // Create a migration
            var migrationsScaffolder = serviceProvider.GetService<IMigrationsScaffolder>();
            Microsoft.EntityFrameworkCore.Migrations.Design.ScaffoldedMigration migration = migrationsScaffolder.ScaffoldMigration("test", "MyProject");

            var rs = Regex.Replace(migration.MigrationCode, @"\s+", string.Empty);
            //crude but, lets just remove all whitespace, and then check it has a blank Up() function
            rs.Contains("Up(MigrationBuildermigrationBuilder){}").ShouldBeTrue();
        }

    }
}

感谢：https://docs.microsoft.com/nl-be/ef/core/cli/services#using-services 和正则表达式。

【讨论】：