The problem with NUnit and app.config

When i run a simple test on connection to DB check i receive an error in NUnit:

[Test]
public void TestConn()
{
    string  connectionString = ConfigurationManager.ConnectionStrings["FertigungRead"].ConnectionString;
    SqlConnection connection = new SqlConnection(connectionString);
    connection.Open();
    Assert.AreEqual(ConnectionState.Open, connection.State);
    connection.Close();
 }

System.NullReferenceException : Object reference not set to an instance of an object.

on line :

connectionString = ConfigurationManager.Conn开发者_如何学GoectionStrings["FertigungRead"].ConnectionString;

Can i use ConfigurationManager in tests?

Yes, you can. You need to be sure that any configuration you are referencing in your tests actually exist in the app.config of the test project.

In other words, the project where your test is in, does not have a connection string "FertigungRead" defined in its app.config.

One way to do this is to add the app.config of the system under test to the test project as a link, this way any changes happen on both projects.

1. Go to NUnit/Project/Edit...
2. In Configuration Property panel go to Configuration File Name
3. Put there yourAssemblyName.dll.config

NB: if does not work try to add path to it, e.g. bin\Debug\ yourAssemblyName.dll.config

Your test project file yourAssemblyName.nunit will be updated.

And yes, be sure App.config in your test project match to what you access in test, i.e.

[Test]
public void TestConn()
{
   var sss = ConfigurationManager.AppSettings["TestKey"];
}

App.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <add key="TestKey" value="testKeyValue"/>
  </appSettings>
</configuration>

I would like to add a point. There is a note in documentation of nunit, and depending upon usage scenario config file naming and placement should be done. I was stuck on this issue for a while.

Documentation says :

If a single assembly is being loaded, then the configuration file is given the name of the assembly file with the config extension. For example, the configuration file used to run nunit.tests.dll must be named nunit.tests.dll.config and located in the same directory as the dll.

If an NUnit project is being loaded, the configuration file uses the name of the project file with the extension changed to config. For example, the project AllTests.nunit would require a configuration file named AllTests.config, located in the same directory as AllTests.nunit. The same rule is followed when loading Visual Studio projects or solutions.

http://www.nunit.org/index.php?p=configFiles&r=2.2.10

Your unit tests should still work as long as you have the same configuration for your test project as for your main project.

I'd suggest using a pre-build event in your test project to copy your application's configuration file over to the test project. This saves having to maintain two sets of configuration.

copy $(SolutionDir)path-to-main-project\Web.config $(ProjectDir)App.config

Why do you need a unit test to see if SqlConnection works? You should test your code, not Microsoft's. I don't really see the point in checking if the connection string is correct either in your unit tests. The configuration used by the unit tests isn't the same as what will be used by your production code.

In general, though, if you need some configuration data for unit tests, create an app.config file in the test project. Populate the appSettings and connectionStrings elements, etc. with appropriate values for your test environment. Don't bother testing whether ConfigurationManager or SqlConnection works, though. You'll just be creating code that you have to maintain, but that doesn't actually verify any of the production code you are writing.

See my answer nunit and configs You need to tell nunit what the name of the config file is. it looks for namespace.config by default it seams

Man give a look at: http://nunit.net/blogs/?p=9

As him suggest I put a MyProjectTests.dll.config in project root and everything works.

An example of my config file is:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
     <add key="TestKey" value="Ok!"/>
</appSettings>
</configuration>

And I'm using the simple: ConfigurationManager.AppSettings["TestKey"];

When a configuration file is used in the project in which a test is run, specific naming conventions must be followed.

The configuration file name should be the name of the assembly file with the config extension. For example, the configuration file used to run MyUnitTest.tests.dll must be named MyUnitTest.tests.dll.config and it should be in the same directory as the MyUnitTest.nunit

Also we can configure this in prebuilds like below

copy $(SolutionDir)path-to-main-project\Web.config $(ProjectDir)App.config 

I was in the same situation and I tried to add app.config to NUnit project but the project couldn't identify it. The tricky workaround for me was to create a class library that contains an app config and turn in into my test project. At the end of the day, all NUnit and its adapter are NuGet packages that can be added for tests to a class library and tests work perfectly fine ran by Visual Studio and Resharper.

And finally debugged my test and received the value from App.config file within my test project: