private static IList<Record> LoadRecords(string fileContent) { const string filepath = "filepath"; var mocks = new MockRepository(MockBehavior.Strict); Mock<IFileSystem> fileSystemMock = mocks.Create<IFileSystem>(); fileSystemMock.Setup(it => it.OpenFileForRead(filepath)) .Returns(new MemoryStream(Encoding.ASCII.GetBytes(fileContent))); IFileSystem fileSystem = fileSystemMock.Object; var reader = new CsvFileReader(fileSystem); reader.Open(filepath); IList<Record> records = new List<Record>(); while (reader.MoveNext()) { records.Add(reader.CurrentRecord); } return records; }