Unit testing: how to access a text file?

Alternatively if you set all your text files to "Copy to build directory" then you could reference their path in your tests by doing this

var directory = Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location);
var path = System.IO.Path.Combine(directory, "myFile.txt");

When I need a chunk of text as part of a unit test and it's more than a line or two, I use an embedded resource. It doesn't clutter your test code, because it's a separate text file in the source code. It gets compiled right into the assembly, so you don't have to worry about copying around a separate file after compilation. Your object under test can accept a TextReader, and you pass in the StreamReader that you get from loading the embedded resource.

You have to add the DeploymentItem attribute to your test class. With this attribute you specify the files which are copied into the out directory for the test run.

For example:

[TestMethod]
[DeploymentItem(@"myfile.txt", "optionalOutFolder")]
public void MyTest()
{
    ...
}

See also: http://msdn.microsoft.com/en-us/library/ms182475.aspx.