Verify multiple images with ApprovalTest

Question

I have a method which generates a few images (1.jpg, 2.jpg...) writing them to the file system. I want to verify the results of this method with ApprovalTest. The problem is that Approvals.verify(image) names the received and approved files as the test method is named. So I cannot verify more than one image with one test.

How could I verify multiple images in one test?

Answer 1

You can use NamerFactory to change information appended to the end of a file. For next test.

[TestFixture]
class Program
{
    [Test]
    [UseReporter(typeof(WinMergeReporter))]
    public void Test1()
    {
        var image1 = @"firstImage.png";
        var image2 = @"secondImage.png";

        NamerFactory.AdditionalInformation = Path.GetFileNameWithoutExtension(image1);
        ApprovalTests.Approvals.Verify(image1);

        NamerFactory.AdditionalInformation = Path.GetFileNameWithoutExtension(image2);
        ApprovalTests.Approvals.Verify(image2);
    }
}

Approval Tests has created two files with firstImage and secondImage before end. See the screenshot for clarity:

My objects are strings, but for your images all would be the same. You would call Approvals.Verify(image) as before, but just changing AdditionalInformation as in the example.

Note: I would not quite recommend verifying two images in one test, because if one Verify will fail - next verifies won't be executed. And there is no way for Approval Tests to concatenate images and verify them in one step, at least if you do this on your own.

Edit: for Java try to use, located at NamerFactory

public static void asMachineSpecificTest(Function0<String> environmentLabeller)
{
    additionalInformation = environmentLabeller.call();
}

and provide appropriate Function, that will return names of your images