File handling in UWP unit tests - unit-testing

Question

I have to setup some unit tests to run on UWP. The unit tests work with files on disk. The files location is configured as a full path (C:\Temp\ for example).
I created a unit test application in Visual Studio 2015, in application manifest I checked Internet (Client), Private Networks and Removable Storage. I also setup a file association for my file type (.dat).
When I run the tests I get Access Denied exceptions when the tests try to open the files on disk. The files are opened using the FileStream class.
Exception Message: Test method UnitTests.TestMethod1 threw exception:
System.UnauthorizedAccessException: Access to the path 'C:\Temp\file.dat' is denied.
How can I setup the test application to be able to open arbitrary files on disk?
Update:
This is a sample test:
public class UnitTest1
{
[TestMethod]
public void TestMethod1()
{
// 1. Open the file using a FileStream
FileStream fs = new FileStream("C:\\Temp\\file.dat", FileMode.Open, FileAccess.Read, FileShare.Read);
// or
// 2. Open the file using UWP file API
Task<Stream> ts = GetStream();
Stream s = ts.Result;
}
async private Task<Stream> GetStream()
{
Windows.Storage.StorageFile sf = await Windows.Storage.StorageFile.GetFileFromPathAsync("C:\\Temp\\file.dat");
Stream s = await sf.OpenStreamForReadAsync();
return s;
}
}
At this moment, after further study, I believe it is not possible to open programmatically arbitrary files on disk from an UWP (test) application, you have to use a file picker to select a file and then open it.

Answer 1

I assume you need a fixed sample of pictures to test your app. I would try to add these samples to lets say Assets folder of your unit test app. Then for every sample file in the Assets folder you want use for testing set the properties such that
Build actions = "Content". This will add the file to the App directory after the build. Then you can access your files like this:
StorageFolder assets = await Package.Current.InstalledLocation.GetFolderAsync("Assets");
StorageFile myTestFile = await assets.GetFileAsync("file1.jpeg");
This in fact ensures, that the test samples are always in the sandbox of your application.
Of course, if you are testing some kind of processing, you can first copy your files from the Assets to the root folder of the App in the [TestInitialize] method and after finishing the tests delete them in [TestFinalize] section. I am using this approach for testing some DB operations on SQLite database (which I move from Assets to root as a file and after the test I delete it). It works for me (VS 2017 UWP app) so it should for you too.

Answer 2

You can run your test once. Then got to Settings|Apps & Features and find your UnitTest project on the test machine. Then grant file permissions there.
This is not ideal, because it is not practical on a Build server.