如何在c#中对if-else语句进行单元测试
本文关键字：语句 单元测试 if-else 中对 | 更新日期: 2023-09-27 18:03:32
我想测试if-else语句是否被执行，"if"块从字典/缓存中返回项并返回输出，而"else"块将输入添加到缓存中并返回输出
IModifyBehavior的接口，带有Apply方法
我有这样的类:
namespace Decorator
{
using System;
/// <summary>
/// Reverse Behavior
/// </summary>
public class ReverseBehavior : IModifyBehavior
{
/// <summary>
/// Applies the specified value.
/// </summary>
/// <param name="value">The value.</param>
/// <returns>result</returns>
public string Apply(string value)
{
var result = string.Empty;
if (value != null)
{
char[] letters = value.ToCharArray();
Array.Reverse(letters);
result = new string(letters);
}
return result;
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
/// <summary>
/// Caching Decorator
/// </summary>
public class CachingDecorator : IModifyBehavior
{
/// <summary>
/// The behavior
/// </summary>
private IModifyBehavior behavior;
public CachingDecorator(IModifyBehavior behavior)
{
if (behavior == null)
{
throw new ArgumentNullException("behavior");
}
this.behavior = behavior;
}
private static Dictionary<string, string> cache = new Dictionary<string, string>();
/// <summary>
/// Applies the specified value.
/// </summary>
/// <param name="value">The value.</param>
/// <returns>
/// value
/// </returns>
public string Apply(string value)
{
////Key = original value, Value = Reversed
var result = string.Empty;
//cache.Add("randel", "lednar");
if(cache.ContainsKey(value))
{
result = cache[value];
}
else
{
result = this.behavior.Apply(value);// = "reversed";
////Note:Add(key,value)
cache.Add(value, result);
}
return result;
}
}
}
这是我当前的测试代码，代码能够通过测试，但我不确定我的实现是否正确:
[TestClass]
public class CachingDecoratorTest
{
private IModifyBehavior behavior;
[TestInitialize]
public void Setup()
{
this.behavior = new CachingDecorator(new ReverseBehavior());
}
[TestCleanup]
public void Teardown()
{
this.behavior = null;
}
[TestMethod]
public void Apply_Cached_ReturnsReversedCachedValue()
{
string actual = "randel";
////store it inside the cache
string cached = this.behavior.Apply(actual);
////call the function again, to test the else block statement
////Implement DRY principle next time
string expected = this.behavior.Apply(actual);
Assert.IsTrue(cached.Equals(expected));
}
[TestMethod]
public void Apply_NotCached_ReturnsReversed()
{
string actual = "randel";
string expected = "lednar";
Assert.AreEqual(expected, this.behavior.Apply(actual));
}
}
首先，我将把这两个类作为适当的单元单独测试。下面我写了我将如何测试这些。为此，我使用NUnit和Moq(在Nuget中可用)作为模拟框架。但是您可以更改测试属性并使用MSTest。
对于相反的行为，我将涵盖常规应用和应用于空文本:
using System;
using System.Linq;
using Decorator;
using NUnit.Framework;
namespace StackOverflow.Tests.HowToTest
{
[TestFixture]
public class ReverseBehaviorTest
{
[Test]
public void Apply()
{
const string someText = "someText";
var target = new ReverseBehavior();
var result = target.Apply(someText);
Assert.AreEqual(someText.Reverse(), result);
}
[Test]
public void Apply_WhenNull()
{
var target = new ReverseBehavior();
var result = target.Apply(null);
Assert.AreEqual(String.Empty, result);
}
}
}
对于CachingDecorator，构造函数的异常抛出，使用缓存和不使用缓存:
using System;
using Decorator;
using Moq;
using NUnit.Framework;
namespace StackOverflow.Tests.HowToTest
{
[TestFixture]
public class CachingDecoratorTest
{
[Test]
public void Constructor()
{
Assert.Throws(typeof(ArgumentNullException), () => new CachingDecorator(null));
}
[Test]
public void Apply_NotCached()
{
var internalBehaviorMock = new Mock<IModifyBehavior>();
internalBehaviorMock.Setup(x => x.Apply(It.IsAny<string>())).Returns<string>(y => y);
const string someText = "someText";
var target = new CachingDecorator(internalBehaviorMock.Object);
target.Apply(someText);
internalBehaviorMock.Verify(x => x.Apply(It.IsAny<string>()), Times.Once());
}
[Test]
public void Apply_Cached()
{
var internalBehaviorMock = new Mock<IModifyBehavior>();
internalBehaviorMock.Setup(x => x.Apply(It.IsAny<string>())).Returns<string>(y => y);
const string someOtherText = "someOtherText";
var target = new CachingDecorator(internalBehaviorMock.Object);
target.Apply(someOtherText);
target.Apply(someOtherText);
internalBehaviorMock.Verify(x => x.Apply(It.IsAny<string>()), Times.Once());
}
}
}
最好的方法是使用一个mock框架(比如Moq)来创建一个假的IModifyBehaviour对象。
然后，Apply_NotCached_ReturnsReversed测试将验证是否调用了模拟对象的Apply方法来生成结果。Apply_Cached_ReturnsReversedCachedValue测试将在不调用模拟对象的Apply方法的情况下检查返回的结果。
实际上，测试缓存的情况并不能证明结果来自缓存。
尝试在测试用例中设置缓存字典值，并在调用Apply(string value)方法后检查计数。
`
public void Apply_Cached_ReturnsReversedCachedValue()
{
Dictionary<string, string> cacheDict = new Dictionary<string, string>() { { "sometext", "txetemos" } };
string str = "sometext";
int dictionaryCountBeforeApply = cacheDict.Count();
//set value to static cache field using reflection, here dictionary count is 1
Type type = typeof(CachingDecorator);
FieldInfo cacheFieldInfo = type.GetField("cache", BindingFlags.NonPublic | BindingFlags.Static);
cacheFieldInfo.SetValue(decorator, cacheDict);
string result = decorator.Apply(str);
int dictionaryCountAfterApply = cacheDict.Count();
Assert.AreEqual(dictionaryCountAfterApply, dictionaryCountBeforeApply);
}
public void Apply_NotCached_ReturnsReversed()
{
Dictionary<string, string> cacheDict = new Dictionary<string, string>() { };
string str = "sometext";
int dictionaryCountBeforeApply = cacheDict.Count();
//set value to static cache field using reflection, here dictionary count is 0
Type type = typeof(CachingDecorator);
FieldInfo cacheFieldInfo = type.GetField("cache", BindingFlags.NonPublic | BindingFlags.Static);
cacheFieldInfo.SetValue(decorator, cacheDict);
string result = decorator.Apply(str);
int dictionaryCountAfterApply = cacheDict.Count();
Assert.AreNotEqual(dictionaryCountAfterApply, dictionaryCountBeforeApply);
}`