这是一个VB。John bly代码的NET移植。Visual Basic不区分大小写，所以他的几个变量名会与类型名发生冲突。

Public Shared ReadOnly Property AssemblyDirectory() As String
    Get
        Dim codeBase As String = Assembly.GetExecutingAssembly().CodeBase
        Dim uriBuilder As New UriBuilder(codeBase)
        Dim assemblyPath As String = Uri.UnescapeDataString(uriBuilder.Path)
        Return Path.GetDirectoryName(assemblyPath)
    End Get
End Property

我怀疑这里真正的问题是您的测试运行程序将您的程序集复制到不同的位置。在运行时没有办法知道程序集是从哪里复制的，但是您可能可以打开一个开关来告诉测试运行程序集从它所在的位置运行，而不是将它复制到影子目录。

当然，对于每个测试运行者，这样的切换可能是不同的。

您是否考虑过将XML数据作为资源嵌入到测试程序集中?

我一直在用汇编。用CodeBase代替Location:

Assembly a;
a = Assembly.GetAssembly(typeof(DaoTests));
string s = a.CodeBase.ToUpper(); // file:///c:/path/name.dll
Assert.AreEqual(true, s.StartsWith("FILE://"), "CodeBase is " + s);
s = s.Substring(7, s.LastIndexOf('/') - 7); // 7 = "file://"
while (s.StartsWith("/")) {
    s = s.Substring(1, s.Length - 1);
}
s = s.Replace("/", "\\");

它一直在工作，但我不再确定它是100%正确的。http://blogs.msdn.com/suzcook/archive/2003/06/26/assembly-codebase-vs-assembly-location.aspx的网页上写着:

"The CodeBase is a URL to the place where the file was found, while the Location is the path where it was actually loaded. For example, if the assembly was downloaded from the internet, its CodeBase may start with "http://", but its Location may start with "C:\". If the file was shadow-copied, the Location would be the path to the copy of the file in the shadow copy dir. It’s also good to know that the CodeBase is not guaranteed to be set for assemblies in the GAC. Location will always be set for assemblies loaded from disk, however."

您可能希望使用CodeBase而不是Location。

Web应用程序?

Server.MapPath("~/MyDir/MyFile.ext")

当开发人员可以更改代码以包含所需的代码片段时，所有建议的答案都是有效的，但如果您希望在不更改任何代码的情况下做到这一点，则可以使用Process Explorer。

它将列出系统中所有正在执行的dll，您可能需要确定正在运行的应用程序的进程id，但这通常并不太难。

我已经写了一个完整的描述如何在II - http://nodogmablog.bryanhogan.net/2016/09/locating-and-checking-an-executing-dll-on-a-running-web-server/中为一个dll做到这一点

与John的答案相同，但扩展方法略少啰嗦。

public static string GetDirectoryPath(this Assembly assembly)
{
    string filePath = new Uri(assembly.CodeBase).LocalPath;
    return Path.GetDirectoryName(filePath);            
}

现在你可以做:

var localDir = Assembly.GetExecutingAssembly().GetDirectoryPath();

或者如果你喜欢:

var localDir = typeof(DaoTests).Assembly.GetDirectoryPath();