单元测试 MongoWriteExceptions

Question

我想使用 Mongo 驱动程序测试我对 MongoWriteException 的处理，这里是一个示例方法：

    private void Update()
    {
        try
        {
            var find = Builders<Filter>.Filter.Eq(e => e.Id, "someId");
            var update = Builders<Filter>.Update.Set(e => e.SomeValue, "AValue");
            _documentStore.MongoCollection<Filter>().UpdateOne(find, update, new UpdateOptions { IsUpsert = true }, CancellationToken.None);
        }
        catch (MongoWriteException mongoWriteException)
        {
            if (mongoWriteException.WriteError.Category != ServerErrorCategory.DuplicateKey)
            {
                throw;
            }
        }
    }

有谁知道如何模拟 MongoWriteException？我试着像这样构造它：

var mongoWriteException = new MongoWriteException(new ConnectionId(new ServerId(new ClusterId(1), new DnsEndPoint("d", 2)), 0), new WriteError(), // <- Protected constructor

但是 WriteError class 有一个内部构造函数

Answer 1

您可以使用反射创建具有内部构造函数的 class 对象。

类似于

 var obj = Activator.CreateInstance(typeof(WriteError), true);

上面代码中的第二个参数是指定Activator寻找非public默认构造函数。

但是这样你就不能初始化任何值或使用带参数的构造函数。

我假设您已经为 mogo DB 库创建了一个假程序集，并使用 shim 来模拟 UpdateOne 方法。

如果是这种情况，您可以填充 WriteError 对象并根据测试用例使属性 "Category" return 任何您想要的值。

它会像

ShimsWriteError.AllInstances.Category = errorObj => ServerErrorCategory.DuplicateKey

上述代码中的语法可能不同。但想法是一样的。

Answer 2

基于the driver's own tests但使用反射获取内部构造函数的小示例

static class MockMongoCollection // : IMongoCollection<TDocument>
{
    private static readonly MongoWriteException __writeException;

    static MockMongoCollection()
    {
        var connectionId = new ConnectionId(new ServerId(new ClusterId(1), new DnsEndPoint("localhost", 27017)), 2);
        var innerException = new Exception("inner");
        var ctor = typeof (WriteConcernError).GetConstructors(BindingFlags.Instance | BindingFlags.NonPublic)[0];
        var writeConcernError = (WriteConcernError)ctor.Invoke(new object[] { 1, "writeConcernError", new BsonDocument("details", "writeConcernError") });
        ctor = typeof (WriteError).GetConstructors(BindingFlags.Instance | BindingFlags.NonPublic)[0];
        var writeError = (WriteError) ctor.Invoke(new object[] {ServerErrorCategory.Uncategorized, 1, "writeError", new BsonDocument("details", "writeError")});
        __writeException = new MongoWriteException(connectionId, writeError, writeConcernError, innerException);
    }

    public static void UpdateOne()
    {
        throw __writeException;
    }
}

class ExampleTests
{
    [Test]
    public void UncategorizedWriteExceptionTest()
    {
        Assert.Throws<MongoWriteException>(MockMongoCollection.UpdateOne);
    }
}

还有一个使用 SerializationInfo 的构造函数可能有类似的味道。

Answer 3

所以我在这里采纳了@logan rakai 的回答 () 并做了一些修改。这是我最终得到的结果。

    [Test]
    public void GivenADuplicateKeyWriteErrorOccurs_WhenCallingUpdateOne_ThenNoExceptionIsThrown()
    {
        // Given
        var someMongoService = CreateSomeObject();

        _mockMongoCollection.Setup(x => x.UpdateOne(It.IsAny<FilterDefinition<SomeObject>>(), It.IsAny<UpdateDefinition<SomeObject>>(), It.IsAny<UpdateOptions>(), default(CancellationToken))).Throws(CreateMongoWriteException(ServerErrorCategory.DuplicateKey));

        // When / Then
        Assert.DoesNotThrow(() => someMongoService.Upsert(new CreateNewSomeObject());
    }

    [Test]
    public void GivenAExceptionOccursWhichIsNotADuplicateKeyWriteError_WhenCallingUpdateOne_ThenTheExceptionIsThrown()
    {
        // Given
        var someMongoService = CreateFilterService();

        var exception = CreateMongoWriteException(ServerErrorCategory.ExecutionTimeout);
        _mockMongoCollection.Setup(x => x.UpdateOne(It.IsAny<FilterDefinition<SomeObject>>(), It.IsAny<UpdateDefinition<SomeObject>>(), It.IsAny<UpdateOptions>(), default(CancellationToken))).Throws(exception);

        // When / Then
        Assert.Throws<MongoWriteException>(() => someMongoService.Upsert(new CreateNewSomeObject());
    }

    public static MongoWriteException CreateMongoWriteException(ServerErrorCategory serverErrorCategory)
    {
        var connectionId = new ConnectionId(new ServerId(new ClusterId(1), new DnsEndPoint("localhost", 27017)), 2);
        
        var writeConcernError = CreateWriteConcernError();
        var writeError = CreateWriteError(serverErrorCategory);
        return new MongoWriteException(connectionId, writeError, writeConcernError, new Exception());
    }

    private static WriteError CreateWriteError(ServerErrorCategory serverErrorCategory)
    {
        var ctor = typeof (WriteError).GetConstructors(BindingFlags.Instance | BindingFlags.NonPublic)[0];
        var writeError = (WriteError)ctor.Invoke(new object[] {serverErrorCategory, 1, "writeError", new BsonDocument("details", "writeError")});
        return writeError;
    }

    private static WriteConcernError CreateWriteConcernError()
    {
        var ctor = typeof(WriteConcernError).GetConstructors(BindingFlags.Instance | BindingFlags.NonPublic)[0];
        return (WriteConcernError)ctor.Invoke(new object[] { 1, "writeConcernError", new BsonDocument("details", "writeConcernError") });
    }

编辑：这里是我们这些使用较少 IDE 的人所需要的命名空间

using System;
using System.Net;
using System.Reflection;
using MongoDB.Bson;
using MongoDB.Driver;
using MongoDB.Driver.Core.Clusters;
using MongoDB.Driver.Core.Connections;
using MongoDB.Driver.Core.Servers;

单元测试 MongoWriteExceptions

Unit testing MongoWriteExceptions

c#

nunit

moq

mongodb

mongodb-.net-driver