blocks|key|1590989|text|与其模拟MongoDB，不如在MongoDB之上模拟一个层。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1590990|您可能需要考虑一个接口，该接口公开存储库上的操作，这些操作与基础数据存储区无关。例如，您可能需要一个抽象出Student类型操作的接口，如下所示：|offset|length|style|CODE|1590991|public+interface+IStudentOperations
{
++++void+Add(Student+student);
}|code-block|syntax|javascript|1590992|在创建其他依赖项时，可以注入上述接口的实例，或您选择的任何更高级别的抽象。|1590993|重点是，不要直接公开MongoDB。|1590994|一旦您这样做了，您可以模拟您创建的所有接口，有一个实现来针对模拟实现进行测试，然后使用它自己的测试来验证在底层实现使用MongoDB时，实现上的操作是否正确。|1590995|虽然绝对是)，但是您获得了持久性不可知论的好处；如果您想切换到CouchDB或elasticsearch，您不必更改对这些接口的调用，只需创建一个新的实现即可。|1590996|因为您正在尝试测试实现。，所以您通常都很好，正如前面所述，MongoDB的大部分函数都是virtual，它对大多数模拟库都很友好。|1590997|也就是说，您必须确保将MongoDatabase传递到存储库中(而不是在存储库中创建它)，以便在单元测试中创建适当的模拟，然后将其传递到存储库实现中进行测试。|1590998|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/12804662/mongodb-unit-testing-in-net/12804721#comment17315878_12804721|1|https://stackoverflow.com/questions/12804662/mongodb-unit-testing-in-net/12804721#comment17316042_12804721^0|0|1H|7|0|0|0|0|0|5|1|0|0|18|7|2|A|1|0|B|D|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|19|8|@$D|1A|E|1B|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|1C|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1D|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|1E|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1F|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|1G|8|@]|9|@$D|1H|E|1I|1|1J]]|A|$]]|$1|U|3|V|5|6|7|1K|8|@$D|1L|E|1M|F|G]]|9|@$D|1N|E|1O|1|1P]]|A|$]]|$1|W|3|X|5|6|7|1Q|8|@$D|1R|E|1S|F|G]]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|1T|8|@]|9|@]|A|$]]]|Z|$10|$5|11|12|13|A|$14|15]]|16|$5|11|12|13|A|$14|17]]]]

Instead of mocking MongoDB, you should be mocking a layer on top of MongoDB.

You might want to consider an interface that exposes the operations on your repository which are agnostic to the underlying data store. For example, you might want an interface that abstracts out operations on <code>Student</code> types, like so:

<pre><code>public interface IStudentOperations
{
 void Add(Student student);
}
</code></pre>

When you create your other dependencies, you inject instances of the above interface, or whichever higher-level abstractions you choose.

The point is, don't expose MongoDB directly.

Once you do that, you can mock the interfaces you create all you want, having one implementation for testing against the mock implementation, and then an actual implementation with it's own tests to validate that operations on the implementation are correct when the underlying implementation is with MongoDB.

While it's definitely <a href="https://stackoverflow.com/questions/12804662/mongodb-unit-testing-in-net/12804721#comment17315878_12804721">possible to mock most of MongoDB's classes (as the methods are <code>virtual</code>)</a>, you gain the benefit of being persistence agnostic; if you want to switch to say, CouchDB or elasticsearch, you don't have to change the calls to these interfaces, you simply create a new implementation.

<hr>

Because <a href="https://stackoverflow.com/questions/12804662/mongodb-unit-testing-in-net/12804721#comment17316042_12804721">you are trying to test the implementation of the repository</a>, then you are generally fine, as has been stated before, most of MongoDB's functions are <code>virtual</code>, which is friendly to most mocking libraries.

That said, you'll have to make sure that you pass the <code>MongoDatabase</code> into your repository (not create it in the repository) so that in your unit tests, you can create the appropriate mock and then pass it into your repository implementation for testing.

blocks|key|2068305|text|参见类似的问题：在node.js中模拟数据库？|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2068306|简而言之，嘲笑MongoDB不是正确的方法。模拟存储库足以测试您自己的单元，但是如果您希望确保正确使用它，或者依赖唯一性约束等，则仍然需要针对MongoDB进行测试。|2068307|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/12526160/mocking-database-in-node-js/12660233#12660233^0|8|F|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]]|C|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@]|C|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]]]

See this similar question: <a href="https://stackoverflow.com/questions/12526160/mocking-database-in-node-js/12660233#12660233">Mocking database in node.js?</a>

In short, mocking MongoDB isn't the right approach. Mocking your repository is adequate for testing your own units, but you'll still need to test against MongoDB if you want to make sure that you're using it correctly, or if you are relying on uniqueness constraints etc.

blocks|key|1591066|text|您需要一个存储库/DAL层来隐藏实现细节。就像这样：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1591067|public+interface+IDataContext<T>
{
+++//+Query
+++IList<T>+GetAll<T>();
+++IList<T>+GetByCriteria<T>(Query+query);
+++T+GetByID<T>(string+id);

+++//+CUD
+++void+Add(T+item);
+++void+Delete(T+item);
+++void+Save(T+item);
}|code-block|syntax|javascript|1591068|对于生产代码，在C#驱动程序的帮助下，使用mongo操作实现接口。|unordered-list-item|1591069|对于单元测试代码，使用内存中的集合模拟接口。|1591070|模拟Add/Delete/Save看起来很简单，有趣的部分是查询函数。幸运的是，由于mongo+C#驱动程序支持LINQ表达式，所以我们可以使用LINQ作为查询语言，而不是重新创建车轮。|1591071|例如，生产代码可能如下所示：|1591072|//+collection+is+a+MongoCollection<T>+object
var+items+=+collection.AsQueryable().Where(...linq+expression...);|1591073|以及单元测试代码(如果您使用Shim，MS测试)：|1591074|using+(ShimsContext.Create())
{++++++++++++++++++
++++ShimLinqExtensionMethods.AsQueryableOf1MongoCollectionOfM0(
++++++++(MongoCollection<T>+x)+=>+Fake_DB_Collection.AsQueryable());
++++//+After+this,+the+above+"collection.AsQueryable()"+will+be+mocked+as+
++++//+an+in-memory+collection,+which+can+be+any+subclass+of+IEnumerable<T>+++++++++++++
}+|1591075|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|I|7|Z|8|@]|9|@]|A|$]]|$1|J|3|K|5|I|7|10|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|11|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|12|8|@]|9|@]|A|$]]|$1|P|3|Q|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|R|3|S|5|6|7|14|8|@]|9|@]|A|$]]|$1|T|3|U|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|V|3|-4|5|6|7|16|8|@]|9|@]|A|$]]]|W|$]]

You need a repository/DAL layer to hide implementation details. Something like this:

<pre><code>public interface IDataContext&lt;T&gt;
{
 // Query
 IList&lt;T&gt; GetAll&lt;T&gt;();
 IList&lt;T&gt; GetByCriteria&lt;T&gt;(Query query);
 T GetByID&lt;T&gt;(string id);

 // CUD
 void Add(T item);
 void Delete(T item);
 void Save(T item);
}
</code></pre>

<ul>
<li>For production code, implement the interface with mongo db operations with the assistance of C# driver</li>
<li>For unit test codes, mock the interface with an in-memory collection</li>
</ul>

It looks straightforward to mock Add/Delete/Save, and the intersting part is query function. Fortunately, since mongo C# driver supports LINQ expressions, we can use LINQ as the query language rather than reinventing the wheels.

For example, the production code may look like:

<pre><code>// collection is a MongoCollection&lt;T&gt; object
var items = collection.AsQueryable().Where(...linq expression...);
</code></pre>

And unit test code (if you go with Shim, MS test):

<pre><code>using (ShimsContext.Create())
{ 
 ShimLinqExtensionMethods.AsQueryableOf1MongoCollectionOfM0(
 (MongoCollection&lt;T&gt; x) =&gt; Fake_DB_Collection.AsQueryable());
 // After this, the above "collection.AsQueryable()" will be mocked as 
 // an in-memory collection, which can be any subclass of IEnumerable&lt;T&gt; 
} 
</code></pre>

blocks|key|1591156|text|如果您专注于单元测试，那么遵循@casperOne的建议，在DB之上模拟一个层(使用存储库模式很容易)。但是，您可能需要集成测试来断言某一行为，然后您需要一个真正的数据库，您有两个选项：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|1591157|选项1:在Docker中运行MongoDB|1591158|像C#驱动程序这样的官方包通过环境变量对一个生命实例(例如在Docker中运行)和传球+(连接字符串)进行测试。|1591159|你需要：|1591160|在码头上启动MongoDB引擎|ordered-list-item|1591161|创建和填充测试数据库|1591162|将xUnit/NUnit测试连接到数据库，并用于每个测试(漂洗和重复)：|1591163|种子试验数据|1591164|执行可测试的活动和检查。|1591165|将数据库恢复到原始状态。|1591166|1591167|拆下码头集装箱。|1591168|对于编写实际测试来说，正式的示例是一个很好的起点。只是不要忘记关闭并行测试执行(您有一个DB实例)。|1591169|选项2:+Mongo2Go+NuGet+-在测试中启动Mongo|1591170|该社区试图减轻管理Docker实例的痛苦，并提出了Mongo2Go+NuGet包，该包从包含的二进制文件(仅为Windows、Linux和MacOs的版本4.4.4)中实例化了MacOs，该包可以在测试开始时从互联网上下载最新版本。|1591171|entityMap|0|LINK|mutability|MUTABLE|url|https://learn.microsoft.com/en-us/dotnet/architecture/microservices/microservice-ddd-cqrs-patterns/infrastructure-persistence-layer-design|1|https://github.com/mongodb/mongo-csharp-driver|2|https://github.com/mongodb/mongo-csharp-driver/blob/df78ce29e112c618b53dad8a488b83239ec7f35e/tests/MongoDB.Driver.Core.TestHelpers/CoreTestConfiguration.cs#L256|3|https://github.com/Mongo2Go/Mongo2Go^0|27|6|16|5|0|0|0|1|6|1|15|2|2|0|0|0|0|1|1|1|1|0|0|0|0|P|8|3|0^^$0|@$1|2|3|4|5|6|7|1L|8|@$9|1M|A|1N|B|C]]|D|@$9|1O|A|1P|1|1Q]]|E|$]]|$1|F|3|G|5|6|7|1R|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|1S|8|@]|D|@$9|1T|A|1U|1|1V]|$9|1W|A|1X|1|1Y]]|E|$]]|$1|J|3|K|5|6|7|1Z|8|@]|D|@]|E|$]]|$1|L|3|M|5|N|7|20|8|@]|D|@]|E|$]]|$1|O|3|P|5|N|7|21|8|@]|D|@]|E|$]]|$1|Q|3|R|5|N|7|22|8|@]|D|@]|E|$]]|$1|S|3|T|5|N|7|23|8|@]|D|@]|E|$]]|$1|U|3|V|5|N|7|24|8|@]|D|@]|E|$]]|$1|W|3|X|5|N|7|25|8|@]|D|@]|E|$]]|$1|Y|3|-4|5|6|7|26|8|@]|D|@]|E|$]]|$1|Z|3|10|5|N|7|27|8|@]|D|@]|E|$]]|$1|11|3|12|5|6|7|28|8|@]|D|@]|E|$]]|$1|13|3|14|5|6|7|29|8|@]|D|@]|E|$]]|$1|15|3|16|5|6|7|2A|8|@]|D|@$9|2B|A|2C|1|2D]]|E|$]]|$1|17|3|-4|5|6|7|2E|8|@]|D|@]|E|$]]]|18|$19|$5|1A|1B|1C|E|$1D|1E]]|1F|$5|1A|1B|1C|E|$1D|1G]]|1H|$5|1A|1B|1C|E|$1D|1I]]|1J|$5|1A|1B|1C|E|$1D|1K]]]]

If you're focused on Unit Tests then follow the @casperOne's advice to mock a layer on top of DB (could be easy with <a href="https://learn.microsoft.com/en-us/dotnet/architecture/microservices/microservice-ddd-cqrs-patterns/infrastructure-persistence-layer-design" rel="nofollow noreferrer">Repository Pattern</a>). However, you might be in need of Integration Tests to assert on a certain behaviour, then you need a real database and you've got 2 options:
<h2>Option 1: Run MongoDB in Docker</h2>
The official packages like the <a href="https://github.com/mongodb/mongo-csharp-driver" rel="nofollow noreferrer">C# Driver</a> run tests against a life instance (e.g. running in Docker) and <a href="https://github.com/mongodb/mongo-csharp-driver/blob/df78ce29e112c618b53dad8a488b83239ec7f35e/tests/MongoDB.Driver.Core.TestHelpers/CoreTestConfiguration.cs#L256" rel="nofollow noreferrer">passing</a> the connection string via environment variables.
You would need:
<ol>
<li>Launch MongoDB engine in Docker</li>
<li>Create &amp; populate a test database</li>
<li>Connect xUnit/NUnit tests to the database and for each test (rinse and repeat):
<ol>
<li>Seed test data</li>
<li>Perform the testable activity and checks</li>
<li>Revert the database to the pristine state</li>
</ol>
</li>
<li>Tear down the Docker container.</li>
</ol>
For writing actual tests the official examples is a good starting point. Just don't forget to turn off parallel test execution (you've got a single DB instance).
<h2>Option 2: Mongo2Go NuGet – launch Mongo on tests kick-off</h2>
The community tried to ease the suffering of managing Docker instances and came up with <a href="https://github.com/Mongo2Go/Mongo2Go" rel="nofollow noreferrer">Mongo2Go</a> NuGet package that instantiates Mongo Community Server from included binaries (only v4.4.4 for Windows, Linux and MacOs) that blows out the package size and can download the latest version from the Internet when testing get kicked off.

I am trying to do tdd and use mongodb as database. But i cant resolve problem of mocking mongodb. Is there any ability to mock mongodb for unit testing in .NET? 

<hr>

Update

I found very good soltion reading blog.
You can find it <a href="http://thoai-nguyen.blogspot.com/2012/06/how-i-mock-mongo-collection.html" rel="noreferrer">here</a>:

Mongodb unit testing in .NET

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在尝试做tdd，并使用mongodb作为数据库。但我不能解决嘲笑mongodb的问题。是否有能力在.NET中模拟mongodb进行单元测试？更新我发现很好的安慰阅读博客。你可以找到它，

问.NET中的Mongodb单元测试
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