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POFaking/mocking an interface gives "no default constructor" error, how can that be?
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  1. POFaking/mocking an interface gives "no default constructor" error, how can that be?
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    copied!<p>I'm trying to write a unit test of a repository implementation. The repository uses RavenDB as a database. For the unit tests, I would like to mock the RavenDB parts. In order to create the mocks (fakes) I'm using FakeItEasy. I figured there wouldn't be any problems with the mocking/faking since the RavenDB API is accessed through interfaces.</p> <p>I do however have a problem when trying to instantiate a specific mock. The relevant parts of my unit test code looks like this:</p> <pre><code>[Fact] public void Test() { UserDocument doc = ...; IQueryable&lt;UserDocument&gt; where = A.Fake&lt;IQueryable&lt;UserDocument&gt;&gt;(); A.CallTo(() =&gt; where.First()).Returns(doc); IRavenQueryable&lt;UserDocument&gt; query = A.Fake&lt;IRavenQueryable&lt;UserDocument&gt;&gt;(); IDocumentSession session = A.Fake&lt;IDocumentSession&gt;(); A.CallTo(() =&gt; session.Query&lt;UserDocument&gt;()).Returns(query); IDocumentStore store = A.Fake&lt;IDocumentStore&gt;(); A.CallTo(() =&gt; store.OpenSession()).Returns(session); . . . } </code></pre> <p>When instantiating the IRavenQueryable fake I get an exception. This is the log from the Xunit.net runner:</p> <pre><code>UnitTest.Test : FakeItEasy.Core.FakeCreationException : Failed to create fake of type "System.Linq.IQueryable`1[UserDocument]". Below is a list of reasons for failure per attempted constructor: No constructor arguments failed: No default constructor was found on the type System.Linq.IQueryable`1[UserDocument]. Stack Trace: vid FakeItEasy.Core.DefaultExceptionThrower.ThrowFailedToGenerateProxyWithResolvedConstructors(Type typeOfFake, String reasonForFailureOfUnspecifiedConstructor, IEnumerable`1 resolvedConstructors) vid FakeItEasy.Creation.FakeObjectCreator.TryCreateFakeWithDummyArgumentsForConstructor(Type typeOfFake, FakeOptions fakeOptions, IDummyValueCreationSession session, String failReasonForDefaultConstructor, Boolean throwOnFailure) vid FakeItEasy.Creation.FakeObjectCreator.CreateFake(Type typeOfFake, FakeOptions fakeOptions, IDummyValueCreationSession session, Boolean throwOnFailure) vid FakeItEasy.Creation.DefaultFakeAndDummyManager.CreateFake(Type typeOfFake, FakeOptions options) vid FakeItEasy.Creation.DefaultFakeCreatorFacade.CreateFake[T](Action`1 options) </code></pre> <p>The "no default constructor found" doesn't make any sense since what I'm trying to fake is an interface. Does anyone have a suggestion what the problem might be?</p>
 

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