这是我创建新应用程序实例的类:
public interface IApplicationInstanceProvider
{
bool CreateNewProcess();
}
public class ApplicationInstanceProvider : IApplicationInstanceProvider
{
public bool CreateNewProcess()
{
Process p = new Process();
p.StartInfo.FileName = System.Reflection.Assembly.GetEntryAssembly().Location;
return p.Start();
}
}
这是我的测试用例:
[TestMethod]
public void TestMethodForAppInstance()
{
IApplicationInstanceProvider provider = new ApplicationInstanceProvider();
bool isCreated = provider.CreateNewProcess();
Assert.AreEqual(isCreated,true);
}
问题是:System.Reflection.Assembly.GetEntryAssembly()
在测试用例执行时为空。但它在应用程序运行时工作正常。
请帮忙!
答案 0 :(得分:1)
您无法按原样测试您的课程,因为您在测试环境中执行 unknown 新进程。它不可行,因为:
Assembly.GetEntryAssembly()
将返回null
。devenv.exe
,chrome.exe
或其他什么。 CreateNewProcess()
方法做了很多事情:它确定执行路径的程序并运行它。此外,其返回值告诉来电者是否已启动新流程或现有流程已被重复使用。单个方法太多东西使得测试变得困难。幸运的是,至少有两种方法可以使您的代码可测试:创建一个专门的ApplicationInstanceProvider
类来进行测试或为它创建一个单独的类。
让我们看看第一种方法:
public class ApplicationInstanceProvider : IApplicationInstanceProvider {
public bool CreateNewProcess() {
Process process = new Process();
process.StartInfo.FileName = ResolveApplicationPath();
return process.Start();
}
protected virtual string ResolveApplicationPath() {
return System.Reflection.Assembly.GetEntryAssembly().Location;
}
}
您将创建一个用于测试的派生类:
sealed class TestApplicationInstanceProvider : ApplicationInstanceProvider {
protected override string ResolveApplicationPath() {
// path to your assembly or a well-known executable executable
// Like %WINDIR%\notepad.exe
return "...";
}
}
然后在你的测试方法中使用它:
[TestMethod]
public void TestMethodForAppInstance() {
var provider = new TestApplicationInstanceProvider();
bool isCreated = provider.CreateNewProcess();
Assert.AreEqual(isCreated, true);
}
请注意,您无法测试Assembly.GetEntryAssembly()
,但您可以测试所有内容。请注意,现在您正在测试是否创建了新的流程实例,但是您没有检查是否已启动正确一个;这将增加代码覆盖率,但实际上几乎没有测试任何内容因为Process.Start()
将始终为可执行文件返回true(运行进程可能重用文档)。这就是为什么你必须分开CreateNewProcess()
责任(不仅为了清晰,而且为了测试)。测试后不要忘记关闭清理方法中的流程实例!
让我们看看第二种方法:第二种方法稍微复杂一点,但它更通用:
public interface IAssemblyResolver {
string GetEntryAssemblyPath();
}
public sealed class DefaultAssemblyResolver : IAssemblyResolver {
public string GetEntryAssemblyPath() {
return System.Reflection.Assembly.GetEntryAssembly().Location;
}
}
public class ApplicationInstanceProvider : IApplicationInstanceProvider {
public ApplicationInstanceProvider(IAssemblyResolver resolver) {
_resolver = resolver;
}
public bool CreateNewProcess() {
Process process = new Process();
process.StartInfo.FileName = _resolver.GetEntryAssemblyPath();
return process.Start();
}
private readonly IAssemblyResolver _resolver;
}
现在你必须创建一个模拟测试:
sealed class TestAssemblyResolver : IAssemblyResolver {
public string GetEntryAssemblyPath() {
// Return path of a well-known test application,
// for example an "empty" console application. You can also
// reuse it to, for example, return different error codes
return Assembly.Load(...);
}
}
测试方法:
[TestMethod]
public void TestMethodForAppInstance() {
var resolver = new TestAssemblyResolver();
var provider = new ApplicationInstanceProvider(resolver);
bool isCreated = provider.CreateNewProcess();
Assert.AreEqual(isCreated, true);
}
您的假应用程序可能是什么样的?
static class Program {
static int Main(string[] args) {
if (args.Length == 0)
return 0;
return Int32.Parse(args[0]);
}
}