c# - 这是测试 ActionResult 的正确方法吗

Question

我对我开发的东西很好奇。我编写了一个自定义 ActionMethod，它是一个自定义 FileResult，它将把给定的 DataTable 导出到 CSV 文件并将其附加到响应中。

我只想知道这是否是正确的测试方法:

这是我的自定义 ActionResult:

/// <summary>
///     Represents an ActionResult that represents a CSV file.
/// </summary>
public class CsvActionResult : FileResult
{
    #region Properties

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    public CsvActionResult(DataTable data)
        : this(data, string.Format("Export_{0}.csv", DateTime.Now.ToShortTimeString()), true, Encoding.Default, ";")
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="name">The filename of the returned file.</param>
    public CsvActionResult(DataTable data, string name)
        : this(data, name, true, Encoding.Default, ";")
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="name">The filename of the returned file.</param>
    /// <param name="usedDelimeter">The delimeter to use as a seperator.</param>
    public CsvActionResult(DataTable data, string name, string usedDelimeter)
        : this(data, name, true, Encoding.Default, usedDelimeter)
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="name">The filename of the returned file.</param>
    /// <param name="addRowHeaders">A boolean that indicates wether to include row headers in the CSV file or not.</param>
    public CsvActionResult(DataTable data, string name, bool addRowHeaders)
        : this(data, name, addRowHeaders, Encoding.Default, ";")
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="name">The filename of the returned file.</param>
    /// <param name="addRowHeaders">A boolean that indicates wether to include row headers in the CSV file or not.</param>
    /// <param name="usedDelimeter">The delimeter to use as a seperator.</param>
    public CsvActionResult(DataTable data, string name, bool addRowHeaders, string usedDelimeter)
        : this(data, name, addRowHeaders, Encoding.Default, usedDelimeter)
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="name">The filename of the returned file.</param>
    /// <param name="usedEncoding">The encoding to use.</param>
    public CsvActionResult(DataTable data, string name, Encoding usedEncoding)
        : this(data, name, true, usedEncoding, ";")
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="name">The filename of the returned file.</param>
    /// <param name="usedEncoding">The encoding to use.</param>
    /// <param name="usedDelimeter">The delimeter to use as a seperator.</param>
    public CsvActionResult(DataTable data, string name, Encoding usedEncoding, string usedDelimeter)
        : this(data, name, true, usedEncoding, usedDelimeter)
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="addRowHeaders">A boolean that indicates wether to include row headers in the CSV file or not.</param>
    public CsvActionResult(DataTable data, bool addRowHeaders)
        : this(data, string.Format("Export_{0}", DateTime.Now.ToShortTimeString()), addRowHeaders, Encoding.Default, ";")
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="addRowHeaders">A boolean that indicates wether to include row headers in the CSV file or not.</param>
    /// <param name="usedDelimeter">The delimeter to use as a seperator.</param>
    public CsvActionResult(DataTable data, bool addRowHeaders, string usedDelimeter)
        : this(data, string.Format("Export_{0}", DateTime.Now.ToShortTimeString()), addRowHeaders, Encoding.Default, usedDelimeter)
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="addRowHeaders">A boolean that indicates wether to include row headers in the CSV file or not.</param>
    /// <param name="usedEncoding">The encoding to use.</param>
    public CsvActionResult(DataTable data, bool addRowHeaders, Encoding usedEncoding)
        : this(data, string.Format("Export_{0}", DateTime.Now.ToShortTimeString()), addRowHeaders, usedEncoding, ";")
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="addRowHeaders">A boolean that indicates wether to include row headers in the CSV file or not.</param>
    /// <param name="usedEncoding">The encoding to use.</param>
    /// <param name="usedDelimeter">The delimeter to use as a seperator.</param>
    public CsvActionResult(DataTable data, bool addRowHeaders, Encoding usedEncoding, string usedDelimeter)
        : this(data, string.Format("Export_{0}", DateTime.Now.ToShortTimeString()), addRowHeaders, usedEncoding, usedDelimeter)
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="usedEncoding">The encoding to use.</param>
    public CsvActionResult(DataTable data, Encoding usedEncoding)
        : this(data, string.Format("Export_{0}", DateTime.Now.ToShortTimeString()), true, usedEncoding, ";")
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="usedEncoding">The encoding to use.</param>
    /// <param name="usedDelimeter">The delimeter to use as a seperator.</param>
    public CsvActionResult(DataTable data, Encoding usedEncoding, string usedDelimeter)
        : this(data, string.Format("Export_{0}", DateTime.Now.ToShortTimeString()), true, usedEncoding, usedDelimeter)
    { }

    /// <summary>
    ///     Creates a new instance of the <see cref="CsvActionResult"/> class.
    /// </summary>
    /// <param name="data">The data which needs to be exported to a CSV file.</param>
    /// <param name="name">The filename of the returned file.</param>
    /// <param name="addRowHeaders">A boolean that indicates wether to include row headers in the CSV file or not.</param>
    /// <param name="usedEncoding">The encoding to use.</param>
    /// <param name="usedDelimeter">The delimeter to use as a seperator.</param>
    public CsvActionResult(DataTable data, string name, bool addRowHeaders, Encoding usedEncoding, string usedDelimeter)
        : base("text/csv")
    {
        this.dataTable = data;
        this.filename = name;
        this.includeRowHeader = addRowHeaders;
        this.encoding = usedEncoding;
        this.delimeter = usedDelimeter;
    }

    /// <summary>
    ///     The datatable that needs to be exported to a Csv file.
    /// </summary>
    private readonly DataTable dataTable;

    /// <summary>
    ///     The filename that the returned file should have.
    /// </summary>
    private readonly string filename;

    /// <summary>
    ///     A boolean that indicates wether to include the row header in the CSV file or not.
    /// </summary>
    private readonly bool includeRowHeader;

    /// <summary>
    ///     The encoding to use.
    /// </summary>
    private readonly Encoding encoding;

    /// <summary>
    ///     The delimeter to use as a seperator.
    /// </summary>
    private readonly string delimeter;

    #endregion Properties

    #region Methods

    /// <summary>
    ///     Start writing the file.
    /// </summary>
    /// <param name="response">The response object.</param>
    protected override void WriteFile(HttpResponseBase response)
    {
        //// Add the header and the content type required for this view.
        //response.AddHeader("Content-Disposition", string.Format("attachment; filename={0}", filename));
        //response.ContentType = base.ContentType;

        // Add the header and the content type required for this view.
        string format = string.Format("attachment; filename={0}", "somefile.csv");
        response.AddHeader("Content-Disposition", format);
        response.ContentType = "text/csv"; //if you use base.ContentType,
        //please make sure this return the "text/csv" during test execution.

        // Gets the current output stream.
        var outputStream = response.OutputStream;

        // Create a new memorystream.
        using (var memoryStream = new MemoryStream())
        {
            WriteDataTable(memoryStream);
            outputStream.Write(memoryStream.GetBuffer(), 0, (int)memoryStream.Length);
        }
    }

    #endregion Methods

    #region Helper Methods

    /// <summary>
    ///     Writes a datatable to a given stream.
    /// </summary>
    /// <param name="stream">The stream to write to.</param>
    private void WriteDataTable(Stream stream)
    {
        var streamWriter = new StreamWriter(stream, encoding);

        // Write the header only if it's indicated to write.
        if (includeRowHeader)
        { WriteHeaderLine(streamWriter); }

        // Move to the next line.
        streamWriter.WriteLine();

        WriteDataLines(streamWriter);

        streamWriter.Flush();
    }

    /// <summary>
    ///     Writes the header to a given stream.
    /// </summary>
    /// <param name="streamWriter">The stream to write to.</param>
    private void WriteHeaderLine(StreamWriter streamWriter)
    {
        foreach (DataColumn dataColumn in dataTable.Columns)
        {
            WriteValue(streamWriter, dataColumn.ColumnName);
        }
    }

    /// <summary>
    ///     Writes the data lines to a given stream.
    /// </summary>
    /// <param name="streamWriter"><The stream to write to./param>
    private void WriteDataLines(StreamWriter streamWriter)
    {
        // Loop over all the rows.
        foreach (DataRow dataRow in dataTable.Rows)
        {
            // Loop over all the colums and write the value.
            foreach (DataColumn dataColumn in dataTable.Columns)
            { WriteValue(streamWriter, dataRow[dataColumn.ColumnName].ToString()); }
            streamWriter.WriteLine();
        }
    }

    /// <summary>
    ///     Write a specific value to a given stream.
    /// </summary>
    /// <param name="writer">The stream to write to.</param>
    /// <param name="value">The value to write.</param>
    private void WriteValue(StreamWriter writer, String value)
    {
        writer.Write(value);
        writer.Write(delimeter);
    }

    #endregion Helper Methods
}

这个类的启动方法是 WriteFile，但由于这是一个 protected 方法，我在我的单元测试项目中创建了一个类，它允许我访问它:

public class CsvActionResultTestClass : CsvActionResult
{
    public CsvActionResultTestClass(DataTable dt)
        : base(dt)
    {
    }

    public new void WriteFile(HttpResponseBase response)
    { base.WriteFile(response); }
}

基本上，我正在创建一个继承自 CsvActionResult 并允许我执行 WriteFile 方法的类。

在我的单元测试中，我确实执行了以下代码:

    [TestMethod]
    public void CsvActionResultController_ExportToCSV_VerifyResponsePropertiesAreSetWithExpectedValues()
    {
        // Initialize the test.
        List<Person> persons = new List<Person>();

        persons.Add(new Person() { Name = "P1_Name", Firstname = "P1_Firstname", Age = 0 });
        persons.Add(new Person() { Name = "P2_Name", Firstname = "P2_Firstname" });

        // Execute the test.
        DataTable dtPersons = persons.ConvertToDatatable<Person>();

        var httpResponseBaseMock = new Mock<HttpResponseBase>();

        //This would return a fake Output stream to you SUT
        httpResponseBaseMock.Setup(x => x.OutputStream).Returns(new Mock<Stream>().Object);
        //the rest of response setup
        CsvActionResultTestClass sut = new CsvActionResultTestClass(dtPersons);

        sut.WriteFile(httpResponseBaseMock.Object);

        //sut
        httpResponseBaseMock.VerifySet(response => response.ContentType = "text/csv");
    }

此方法创建一个 DataTable 并模拟 HttpResponseBase。

然后我调用方法 WriteFile 并检查响应的内容类型。

这是正确的测试方法吗？如果还有其他更好的测试方法，请告诉我。

亲切的问候，

Answer 1

您在单元测试中做了什么，以及您如何验证 SUT 的行为是否正确。您决定使用继承来创建可测试版本的技术也很好。这称为“Extract and Override”。我会对您的测试和可测试的 sut(被测系统)进行简单的更改。

一个。我会将名称更改为 TestableCsvActionResult

 public class TestableCsvActionResult : CsvActionResult
 {
     public TestableCsvActionResult(DataTable dt)
    : base(dt)
     {
     }

     public new void WriteFile(HttpResponseBase response)
     { base.WriteFile(response); }
 }

这样你提供一个可测试的版本就更有意义了。而且它不是假的。

单元测试

    [TestMethod]
    public void CsvActionResultController_ExportToCSV_VerifyResponseContentTypeIsTextCsv()
    {
        // Arrange
        var httpResponseBaseMock = new Mock<HttpResponseBase>();
        httpResponseBaseMock.Setup(x => x.OutputStream).Returns(new Mock<Stream>().Object);
        var sut = new CsvActionResultTestClass(new DataTable());

        //Act
        sut.WriteFile(httpResponseBaseStub.Object);

        //Verify
        httpResponseBaseMock.VerifySet(response => response.ContentType = "text/csv");
    }

您的测试方法名称很好，而且可读。由于您只是在验证“text/csv”，因此我会更明确地说明名称。这样就很清楚你的意图了。但是，如果您有多个验证，那么您拥有的名称就足够了。

ConverToDataTable 不是必需的。使测试尽可能简单。使用使您的测试通过所需的最小量。

除了一般评论(由我整理)之外，其他一切似乎都符合目的。