[Moq] Mocking DbDataProvider

[Nuno Leong]

Hi,

I'm relatively new to mocking frameworks so bear with me. :)

We're testing a couple of classes which depend on IDb* objects (sort
of a DAL). I was trying to mock DbFactoryProvider so we can inject
mock IDb objects to the classes.

So, i did this:

Mock<IDbCommand> mockIDbCommand = new
Mock<IDbCommand>(MockBehavior.Strict);
mockIDbCommand.SetupAllProperties();

Mock<IDbConnection> mockIDbConnection = new
Mock<IDbConnection>(MockBehavior.Strict);
mockIDbConnection.SetupAllProperties();
mockIDbConnection.Setup(c =>
c.CreateCommand()).Returns(mockIDbCommand.Object);

Mock<DbProviderFactory> mockDbProviderFactory = new
Mock<DbProviderFactory>(MockBehavior.Strict);
mockDbProviderFactory.Setup(f =>
f.CreateConnection()).Returns(mockIDbConnection.Object);

The last line won't compile since DbProviderFactory.CreateConnection()
returns an DbConnection and not an IDbConnection.

The problem is can't mock DbConnection.CreateCommand() since that
method is not virtual/overridable.

I tried casting mockIDbConnection.Object to DbConnection but that
doesn't work.

Any suggestions on how to solve this problem ?

Huge thanks,
Nuno Leong

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[Daniel Cazzulino]

when an (typically legacy) API is not amenable to mocking, you can wrap it in a new interface and use that throughout your codebase.

An example of how to do this can be found at http://weblogs.asp.net/cibrax/archive/2008/05/16/unit-tests-for-wcf.aspx, where Pablo does esencially the same thing for the unmock-able WCF service context.

HTH

/kzu

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Daniel Cazzulino | Developer Lead | XML MVP | Clarius Consulting | +1 425.329.3471

[Nuno Leong]

Hi Daniel,

It worked perfectly, thanks a lot.

Cheers,
Nuno Leong

On May 21, 5:44 pm, Daniel Cazzulino <dan...@cazzulino.com> wrote:
> when an (typically legacy) API is not amenable to mocking, you can wrap it
> in a new interface and use that throughout your codebase.
>

> An example of how to do this can be found athttp://weblogs.asp.net/cibrax/archive/2008/05/16/unit-tests-for-wcf.aspx,

[e...@baskoro.org]

G'day,

Alternatively if you are targeting .NET 4.5 and using Moq 4 the following snippet works without creating wrappers:

// Mock the data reader

var dataReaderMock = new Mock<DbDataReader>();

dataReaderMock

    .Setup(dataReader => dataReader.HasRows)

    .Returns(true)

;

dataReaderMock.As<IDisposable>();

// Mock the command

var commandMock = new Mock<DbCommand>();

commandMock

    .Protected()

    .Setup<DbDataReader>("ExecuteDbDataReader", new object[] { CommandBehavior.Default })

    .Returns(dataReaderMock.Object)

;

commandMock.As<IDisposable>();

// Mock the connection

var connectionMock = new Mock<DbConnection>();

connectionMock

    .Protected()

    .Setup<DbCommand>("CreateDbCommand")

    .Returns(commandMock.Object)

;

connectionMock.As<IDisposable>();

// Mock the provider factory

var providerFactoryMock = new Mock<DbProviderFactory>();

providerFactoryMock

    .Setup(providerFactory => providerFactory.CreateConnection())

    .Returns(connectionMock.Object)

;

Warm regards,

Eki Baskoro B.Com. B.Eng. SCJP MCTS MCP