How to unit test FileContentResult?

Question

I have a method that exports data into CSV file.

public FileContentResult Index(SearchModel search)
{    
    ...
    if (search.Action == SearchActionEnum.ExportToTSV)
    {
        const string fileName = "Result.txt";
        const string tab = "\t";
        var sb = BuildTextFile(result, tab);
        return File(new UTF8Encoding().GetBytes(sb.ToString()), "text/tsv", fileName);
    }
    if (search.Action == SearchActionEnum.ExportToCSV)
    {
        const string fileName = "Result.csv";
        const string comma = ",";
        var sb = BuildTextFile(result, comma);
        return File(new UTF8Encoding().GetBytes(sb.ToString()), "text/csv", fileName);
    }
    return null;
}

My test, in NUnit:

[Test]
public void Export_To_CSV()
{
    #region Arrange
    ...
    #endregion

    #region Act

    var result = controller.Index(search);

    #endregion

    #region Assert
    result.ShouldSatisfyAllConditions(
        ()=>result.FileDownloadName.ShouldBe("Result.csv"),
        ()=>result.ContentType.ShouldBe("text/csv")
        );
    #endregion
}

In addition to FileDownloadName and ContentType, I want to check the content of the result.

It seems I should look into result.FileContents, but it is a byte[].

How can I get hold of the result as a text string?

And is my result saved somewhere as a CSV file in the solution every time I run the test?

Answer 1

In your Index method, you are using the following code to encode the text content as bytes:

return File(new UTF8Encoding().GetBytes(sb.ToString()), "text/csv", fileName);

To get from the bytes to the original text, you can use:

string textContents = new UTF8Encoding().GetString(result.FileContents);

The result is NOT saved anywhere as a CSV.