Instantiating a .NET form in Runtime mode inside a unit test

Question

In order to protect against poor designer merges that mess up control initialization, I decided to add some "unit tests" that try to create instances of my System.Windows.Forms.Form objects, like so:

[TestMethod]
public void TestMyForm()
{
    var form = new MyForm();//if exception is thrown, fail test...
}

Unfortunately, DevExpress doesn't seem to like having its controls instantiated from within the unit test runner and it shows a nagging splash screen with "License expired" that requires user interaction in order to continue running the tests. How can this be avoided?

Answer 1

After some hours of thorough digging, I discovered that System.ComponentModel.Design.RuntimeLicenseContext.GetSavedLicenseKey() is being called by DevExpress and this method makes a call to Assembly.GetEntryAssembly(), which happens to return null when called from within a unit test, and this makes DevExpress believe that its being used in designer mode, which indeed requires a valid license.

Having this clue, I managed to find a really underrated answer from user @Manjay that provides an elegant solution to this problem by using reflection. I took the liberty to provide the following slightly modified version of Jamie Cansdale's code, which can be found here:

public static void SetEntryAssembly()
{
    if (Assembly.GetEntryAssembly() != null)
    {
        return;
    }

    Assembly assembly = Assembly.GetCallingAssembly();

    AppDomainManager manager = new AppDomainManager();
    FieldInfo entryAssemblyfield = manager.GetType().GetField("m_entryAssembly", BindingFlags.Instance | BindingFlags.NonPublic);
    if (entryAssemblyfield != null)
    {
        entryAssemblyfield.SetValue(manager, assembly);
    }

    AppDomain domain = AppDomain.CurrentDomain;
    FieldInfo domainManagerField = domain.GetType().GetField("_domainManager", BindingFlags.Instance | BindingFlags.NonPublic);
    if (domainManagerField != null)
    {
        domainManagerField.SetValue(domain, manager);
    }
}

Answer 2

You may want to check out Coded UI Tests for testing the UI of WinForms applications. http://msdn.microsoft.com/en-us/library/dd286726.aspx