Unit tests are automated tests written to verify that individual units of code, such as class libraries, work as expected. They are popular because they help catch bugs early and during the development process, and make code maintenance easier over time.

This article shows how to add unit tests using MSTest to a class library project that uses TX Text Control. In addition, it shows how to deal with licensing when you are testing class libraries.

Important

This article contains information that applies only to TX Text Control versions 32.0 SP2 and later.

Class Library Project

Assume that you already have your class library project open in Visual Studio, which looks like the one in the following code snippet.

namespace MyTextControlClassLibrary
{
  public static class DocumentProcessing  
  {
    public static byte[] GeneratePDF(string html)
    {
      using (TXTextControl.ServerTextControl tx = new TXTextControl.ServerTextControl())
      {
        byte[] data;

        tx.Create();
        tx.Load(html, TXTextControl.StringStreamType.HTMLFormat);
        tx.Save(out data, TXTextControl.BinaryStreamType.AdobePDF);

        return data;
      }
    }
  }
}

Typically, this class would be used by a .NET calling assembly that holds the TX Text Control license, so the ServerTextControl instance used is automatically licensed in the class library. By default, the calling assembly must have a valid license of TX Text Control to work properly.

Adding the License

When you are testing a class library that uses TX Text Control, you need to add the license to the class library. To do this, add the following code to the constructor of your class (where DocumentProcessing is the class name):

TXTextControl.ServerTextControl.EntryAssembly = typeof(DocumentProcessing).Assembly;

This ensures that the TX Text Controls licensing mechanism looks in the class library to find the license. After adding this, the complete class should look similar to the following:

namespace MyTextControlClassLibrary
{
  public static class DocumentProcessing  
  {
    static DocumentProcessing() {
      TXTextControl.ServerTextControl.EntryAssembly =
      typeof(DocumentProcessing).Assembly;
    }

    public static byte[] GeneratePDF(string html)
    {
      using (TXTextControl.ServerTextControl tx = new TXTextControl.ServerTextControl())
      {
        byte[] data;

        tx.Create();
        tx.Load(html, TXTextControl.StringStreamType.HTMLFormat);
        tx.Save(out data, TXTextControl.BinaryStreamType.AdobePDF);

        return data;
      }
    }
  }
}

Unit Test Project

Now, let's add a unit test project to the solution.

1. Right-click the solution in Solution Explorer, select Add, and then New Project.

2. In the Add a new project dialog, search for Test, and then select the MSTest Test Project template and click Next.

   

3. Provide a name for the project and choose your preferred Framework (.NET 8.0 in this example), and then click Create.

Adding the Project Reference

After creating the unit test project, add a reference to the class library project.

1. In the Solution Explorer, select your created test project and choose Add Project Reference... from the Project main menu.

2. In the Reference Manager, select the Projects tab, and then select your class library project and confirm with OK. The Solution Explorer will now show the reference to the class library project.

   

Adding the Unit Test

Now, let's add a unit test to the project.

1. Open the UnitTest1.cs file and replace the content with the following code:

   [TestMethod]
   public void TestConversion()
   {
     string html = "<html><body><h1>Hello, World!</h1></body></html>";
     byte[] pdf = MyTextControlClassLibrary.DocumentProcessing.GeneratePDF(html);
   
     Assert.IsNotNull(pdf);
   }

The unit test creates an instance of the DocumentProcessing class and calls the GeneratePDF method. The method should return a byte array that is not null.

Running the Unit Test

Now, you can run the unit test by right-clicking the test method in the Test Explorer and selecting Run Selected Tests.

After running the test, the Test Explorer will show the result of the test.

Using TX Text Control in Test Methods

You can also use an instance of the TX Text Control in the test method itself. Since the license is already included in the tested class library, all you need to do to use TX Text Control is to add the NuGet package to your test project.

For example, you can add the following code to the test method:

[TestClass]
public class UnitTest1
{
  [TestMethod]
  public void TestConversion()
  {
    string html = "<html><body><h1>Hello, World!</h1></body></html>";
    byte[] pdf = MyTextControlClassLibrary.DocumentProcessing.GeneratePDF(html);

    Assert.IsNotNull(pdf);

    // use TX Text Control to load the PDF and check for the text
    using (TXTextControl.ServerTextControl tx = new TXTextControl.ServerTextControl())
    {
      tx.Create();
      tx.Load(pdf, TXTextControl.BinaryStreamType.AdobePDF);

      if (tx.Text.Contains("Hello, World!"))
      {
        Assert.IsTrue(true);
      }
      else
      {
        Assert.Fail();
      }
        
    }
  }
}

This code will use TX Text Control to open the generated PDF document to check for the text added using the class library.

Conclusion

Adding unit tests to a class library project that uses TX Text Control is a great way to ensure that the code works as expected. By adding the license to the class library, you can test the class library without the need for a valid license in the test project.