Mongo2Go - MongoDB for integration tests & local debugging

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Windows Build (Windows Server 2016)

Mongo2Go is a managed wrapper around the latest MongoDB binaries. It targets .NET Standard 1.6 (and .NET 4.6 for legacy environments) and works with Windows, Linux and macOS. This Nuget package contains the executables of mongod, mongoimport and mongoexport for Windows, Linux and macOS .

Brought to you by Johannes Hoppe, follow him on Twitter.

Mongo2Go has two use cases:

1. Providing multiple, temporary and isolated MongoDB databases for unit tests (or to be precise: integration tests)
2. Providing a quick to set up MongoDB database for a local developer environment

Unit Test / Integration test

With each call of the static method MongoDbRunner.Start() a new MongoDB instance will be set up. A free port will be used (starting with port 27018) and a corresponding data directory will be created. The method returns an instance of MongoDbRunner, which implements IDisposable. As soon as the MongoDbRunner is disposed (or if the Finalizer is called by the GC), the wrapped MongoDB process will be killed and all data in the data directory will be deleted.

Local debugging

In this mode a single MongoDB instance will be started on the default port (27017). No data will be deleted and the MongoDB instance won’t be killed automatically. Multiple calls to MongoDbRunner.StartForDebugging() will return an instance with the State “AlreadyRunning”. You can ignore the IDisposable interface, as it won’t have any effect. I highly recommend to not use this mode on productive machines! Here you should set up a MongoDB as it is described in the manual. For you convenience the MongoDbRunner also exposes mongoexport and mongoimport which allow you to quickly set up a working environment.

Single server replica set mode to enable transactions

MongoDbRunner.Start() can be set up to take in an optional boolean parameter called singleNodeReplSet. When passed in with the value true - (MongoDbRunner.Start(singleNodeReplSet: true))

• a single node mongod instance will be started as a replica set with the name singleNodeReplSet. Replica set mode is required for transactions to work in MongoDB 4.0 or greater

Replica set initialization requires the use of a short delay to allow for the replica set to stabilize. This delay is linked to a timeout value of 5 seconds.

If the timeout expires before the replica set has stabilized a TimeoutException will be thrown.

The default timeout can be changed through the optional parameter singleNodeReplSetWaitTimeout, which allows values between 0 and 65535 seconds: MongoDbRunner.Start(singleNodeReplSet: true, singleNodeReplSetWaitTimeout: 10)

Additional mongod arguments

MongoDbRunner.Start() can be set up to consume additional mongod arguments. This can be done using the string parameter called additionalMongodArguments.

The list of additional arguments cannot contain arguments already defined internally by Mongo2Go. An ArgumentException will be thrown in this case, specifying which additional arguments are required to be discarded.

Example of usage of the additional mongod arguments: MongoDbRunner.Start(additionalMongodArguments: "--quiet")

Installation

The Mongo2Go Nuget package can be found at https://nuget.org/packages/Mongo2Go/

Search for „Mongo2Go“ in the Manage NuGet Packages dialog box or run:

PM> Install-Package Mongo2Go

or run for the legacy .NET 4.6 package:

PM> Install-Package Mongo2Go -Version 1.1.0

in the Package Manager Console.

• The new 2.x branch targets .NET Standard 1.6, please use the latest packages if possible.
• The old 1.x branch targets good-old classic .NET 4.6.1. This is for legacy environments only. No new features will be added, only bugfixes will be made.

Examples

Example: Integration Test (here: Machine.Specifications & Fluent Assertions)

[Subject("Runner Integration Test")]
public class when_using_the_inbuild_serialization : MongoIntegrationTest
{
    static TestDocument findResult;
    
    Establish context = () =>
        {
            CreateConnection();
            _collection.Insert(TestDocument.DummyData1());
        };

    Because of = () => findResult = _collection.FindOneAs<TestDocument>();

    It should_return_a_result = () => findResult.ShouldNotBeNull();
    It should_hava_expected_data = () => findResult.ShouldHave().AllPropertiesBut(d => d.Id).EqualTo(TestDocument.DummyData1());

    Cleanup stuff = () => _runner.Dispose();
}

public class MongoIntegrationTest
{
    internal static MongoDbRunner _runner;
    internal static MongoCollection<TestDocument> _collection;

    internal static void CreateConnection()
    {
        _runner = MongoDbRunner.Start();
        
        MongoClient client = new MongoClient(_runner.ConnectionString);
        MongoDatabase database = client.GetDatabase("IntegrationTest");
        _collection = database.GetCollection<TestDocument>("TestCollection");
    }
}    

More tests can be found at https://github.com/Mongo2Go/Mongo2Go/tree/master/src/Mongo2GoTests/Runner

Example: Exporting seed data

using (MongoDbRunner runner = MongoDbRunner.StartForDebugging()) {

    runner.Export("TestDatabase", "TestCollection", @"..\..\App_Data\test.json");
}

Example: Importing for local debugging (compatible with ASP.NET MVC 4 Web API as well as ASP.NET Core)

public class WebApiApplication : System.Web.HttpApplication
{
    private MongoDbRunner _runner;

    protected void Application_Start()
    {
        _runner = MongoDbRunner.StartForDebugging();
        _runner.Import("TestDatabase", "TestCollection", @"..\..\App_Data\test.json", true);

        MongoClient client = new MongoClient(_runner.ConnectionString);
        MongoDatabase database = client.GetDatabase("TestDatabase");
        MongoCollection<TestObject> collection = database.GetCollection<TestObject>("TestCollection");

        /* happy coding! */
    }

    protected void Application_End()
    {
        _runner.Dispose();
    }
}

Example: Transactions (New feature since v2.2.8)

 public class when_transaction_completes : MongoTransactionTest
    {
        private static TestDocument mainDocument;
        private static TestDocument dependentDocument;
        Establish context = () =>

        {
            _runner = MongoDbRunner.Start(singleNodeReplSet: true);
             client = new MongoClient(_runner.ConnectionString);
            database = client.GetDatabase(_databaseName);
            _mainCollection = database.GetCollection<TestDocument>(_mainCollectionName);
            _dependentCollection = database.GetCollection<TestDocument>(_dependentCollectionName);
            _mainCollection.InsertOne(TestDocument.DummyData2());
            _dependentCollection.InsertOne(TestDocument.DummyData2());
        };

        private Because of = () =>
        {
            var filter = Builders<TestDocument>.Filter.Where(x => x.IntTest == 23);
            var update = Builders<TestDocument>.Update.Inc(i => i.IntTest, 10);

            using (var sessionHandle = client.StartSession())
            {
                try
                {
                    var i = 0;
                    while (i < 10)
                    {
                        try
                        {
                            i++;
                            sessionHandle.StartTransaction(new TransactionOptions(
                                readConcern: ReadConcern.Local,
                                writeConcern: WriteConcern.W1)); 
                            try
                            {
                                var first = _mainCollection.UpdateOne(sessionHandle, filter, update);
                                var second = _dependentCollection.UpdateOne(sessionHandle, filter, update);
                            }
                            catch (Exception e)
                            {
                                sessionHandle.AbortTransaction();
                                throw;
                            }

                            var j = 0;
                            while (j < 10)
                            {
                                try
                                {
                                    j++;
                                    sessionHandle.CommitTransaction();
                                    break;
                                }
                                catch (MongoException e)
                                {
                                    if (e.HasErrorLabel("UnknownTransactionCommitResult"))
                                        continue;
                                    throw;
                                }
                            }
                            break;
                        }
                        catch (MongoException e)
                        {
                            if (e.HasErrorLabel("TransientTransactionError"))
                                continue;
                            throw;
                        }
                    }
                }
                catch (Exception e)
                {
                    //failed after multiple attempts so log and do what is appropriate in your case
                }
            }

             mainDocument = _mainCollection.FindSync(Builders<TestDocument>.Filter.Empty).FirstOrDefault();
             dependentDocument = _dependentCollection.FindSync(Builders<TestDocument>.Filter.Empty).FirstOrDefault();
        };
        
        It main_should_be_33 = () => mainDocument.IntTest.Should().Be(33);
        It dependent_should_be_33 = () => dependentDocument.IntTest.Should().Be(33);
        Cleanup cleanup = () => _runner.Dispose();
    }

Changelog

Mongo2Go 2.2.16, December 13 2020

• fix for non existing starting path for binary search (PR #107, fixes #105 - many thanks to Gurov Yury)

Mongo2Go 2.2.15, December 12 2020

• throw exception if cluster is not ready for transactions after singleNodeReplSetWaitTimeout (PR #103 - many thanks for the continued support by José Mira)

Mongo2Go 2.2.14, October 17 2020

• fixes a bug with pulling mongo binaries from wrong version (PR #87, fixes #86 - many thanks to mihevc)
• ensures transaction is ready (solves error message: System.NotSupportedException : StartTransaction cannot determine if transactions are supported because there are no connected servers.) (PR #101, fixes #89, #91 and #100 - many thanks to liangshiwei)

Mongo2Go 2.2.12, September 07 2019

• performance: waits for replica set ready log message, or throws if timeout expires, instead of using Thread.Sleep(5000) (PR #83, fixes #80 - many thanks again to José Mira)

Mongo2Go 2.2.11, May 10 2019

• allows additional custom MongoDB arguments (PR #69, fixes #68 - many thanks to José Mira)
• adds option to set port for StartForDebugging() (PR #72, fixes #71 - many thanks to Danny Bies)

Mongo2Go 2.2.9, February 04 2019

• fixes a file path issue on Linux if you run on an SDK version beyond .NET Standard 1.6 (PR #63, fixes #62 and #61) - many thanks to Jeroen Vannevel)
• continuous integration runs on Linux (Travis CI) and Windows (AppVeyor) now

Mongo2Go 2.2.8, October 12 2018

• updated MongoDB binaries to 4.0.2 to support tests leveraging transaction across different collections and databases
• updated MongoDB C# driver to 2.7.0 to be compatible with MongoDB 4.0
• adds singleNodeReplSet paramter to MongoDbRunner.Start which allows mongod instance to be started as a replica set to enable transaction support (PR #57 - many thanks to Mahi Satyanarayana)
• fixes port lookup for UnixPortWatcher (PR #58 - many thanks to Viktor Kolybaba)

Mongo2Go 2.2.7, August 13 2018

• updates the MongoBinaryLocator to look for binaries in the nuget cache if they are not found in the project directory.
  • this will make Mongo2Go compatible with projects using the nuget PackageReference option. (PR #56, fixes #39 and #55)
• adds the binariesSearchDirectory parameter to MongoDbRunner.Start which allows an additional binaries search directory to be provided.
  • this will make the db runner more flexible if someone decides to use it in some unpredictable way.
• many thanks to Nicholas Markkula

Mongo2Go 2.2.6, July 20 2018

• fixes broken linux support (fixes #47)

Mongo2Go 2.2.5, July 19 2018

• fixes unresponsive process issue (PR #52, fixes #49)
• many thanks to narendrachava

Mongo2Go 2.2.4, June 06 2018

• better support for TeamCity: removed MaxLevelOfRecursion limitation when searching for MongoDb binaries (PR #50, fixes #39)
• many thanks to Stanko Culaja

Mongo2Go 2.2.2, June 05 2018

• includes mongod, mongoimport and mongoexport v3.6.1 for Windows, Linux and macOS via PR #46, which fixes #45
• many thanks to Joe Chan

Mongo2Go 2.2.1, November 23 2017

• no MongoDB binaries changed, still .NET Standard 1.6
• feature: uses temporary directory instead of good-old windows style C:\data\db by default (PR #42) - MongoDbRunner.Start() and MongoDbRunner.StartForDebugging() will now work without any extra parameters for Linux/macOS
• bugfix: runs again on Linux/macOS, by making the binaries executable (PR #42, which fixes #37 and might also fix #43)
• internal: Unit Tests are running again (PR #44, which fixes #31, #40)
• internal: No hardcoded path passed to MongoDbRunner constructor (fixes 41)
• many thanks to Per Liedman

Mongo2Go 2.2.0, August 17 2017

• includes mongod, mongoimport and mongoexport v3.4.7 for Windows, Linux and macOS
• targets .NET Standard 1.6 (can be used with .NET Core 1.0 / 1.1 / 2.0)
• many thanks to Aviram Fireberger

Mongo2Go 2.1.0, March 10 2017

• skips v2.0 to have same numbers as v1.x.
• no MongoDB binaries changed since 2.0.0-alpha1 (still MongoDB v3.2.7 for Windows, Linux and macOS)
• targets .NET Standard 1.6 (can be used with .NET Core 1.0 / 1.1)
• bugfix: prevent windows firewall popup (PR #30, which fixes #21)
• many thanks to kubal5003

Mongo2Go 1.1.0, March 10 2017 (legacy branch!)

• no MongoDB binaries changed since v1.0 (still MongoDB v3.2.7 for Windows, Linux and macOS)
• targets .NET 4.6.1
• bugfix: prevent windows firewall popup (PR #29, which fixes #21)
• many thanks to kubal5003

Mongo2Go 2.0.0-alpha1, December 19 2016

• this version has no support for .NET Framework 4.6, please continue to use the stable package v.1.0.0
• NEW: first support of .NET Standard 1.6 (#25)
  • many thanks to Hassaan Ahmed
  • see the Wiki for more information about .NET Core 1.0 / .NET Standard 1.6

How to contribute

Just fork the project, make your changes send us a PR.
You can compile the project with Visual Studio 2017 and/or the .NET Core 2.0 CLI!

In the root folder, just run:

dotnet restore
dotnet build
dotnet test src/Mongo2GoTests