為Asp.net控件寫單元測試(ViewState)

 通常一個典型的asp.net控件至少會用ViewState存儲一些屬性,以便于在頁面postback后不用重新設置。在這篇文章里我將介紹如何為控件寫單元測試，以確保一個屬性被正確的保存在ViewState里。

        為了演示，我寫了一個簡單的控件。

namespace Eilon.Sample.Controls {
using System;
using System.Web.UI;
public class NewLabel : Control {
public string Text {
get {
string s = ViewState["Text"] as string;
return s ?? String.Empty;
}
set {
ViewState["Text"] = value;
}
}
protected override void Render(HtmlTextWriter writer) {
writer.Write(Text);
}
}
}

        這個控件只是簡單的將它唯一的屬性Text輸出。

        好的，讓我們寫一個簡單的單元測試，以確保這個控件正確的工作。

namespace Eilon.Sample.Controls.Test {
using System;
using System.IO;
using System.Web.UI;
using Microsoft.VisualStudio.TestTools.UnitTesting;
[TestClass]
public class NewLabelTest {
[TestMethod]
public void TextReturnsEmptyStringDefault() {
NewLabel label = new NewLabel();
Assert.AreEqual(String.Empty, label.Text,

"Default text should be empty string (not null)");
}
[TestMethod]
public void GetSetText() {
const string value = "Some Text";
NewLabel label = new NewLabel();
label.Text = value;
Assert.AreEqual(value, label.Text,

"Property value isn't the same as what we set");
}
[TestMethod]
public void RenderEmpty() {
NewLabel label = new NewLabel();
Assert.AreEqual(String.Empty, GetRenderedText(label),

"Shouldn't have rendered anything");
}
[TestMethod]
public void RenderWithText() {
const string value = "Some Text";
NewLabel label = new NewLabel();
label.Text = value;
Assert.AreEqual(value, GetRenderedText(label),

"Should have rendered the text");
}
private static string GetRenderedText(Control c) {
HtmlTextWriter writer = new HtmlTextWriter(new StringWriter());
c.RenderControl(writer);
return writer.InnerWriter.ToString();
}
}
}

原文轉自：http://www.kjueaiud.com