public void ReaderMustReturnOk()
{
var fakeFileContents = "Id,Person,Population,Test \n 1,2,3,4";
byte[] fakeFileBytes = Encoding.UTF8.GetBytes(fakeFileContents);
var fakeStream = new MemoryStream(fakeFileBytes);
mockFileManager
.Setup(f => f.GetStreamReader(It.IsAny <string>()))
.Returns(() => new StreamReader(fakeStream));
var arg1 = "1";
var arg2 = "first.csv";
var arg3 = "Id";
var table = reader.ConvertCSVtoDataTable(arg1, arg2, arg3);
Assert.IsTrue(table.PrimaryKey.FirstOrDefault().ColumnName == "Id");
Assert.IsTrue(table.Rows.Count == 1);
Assert.IsTrue(table.Columns.Count == 4);
}