Is it possible to unit test BundleConfig in MVC4? - unit-testing

Question

As far as I can tell, the answer is no. The issue I'm seeing comes from the Include(params string[]) method in the System.Web.Optimization.Bundle class. Internally this invokes System.Web.Optimization.IncludeDirectory(string, string, bool), which in turn uses this code:
DirectoryInfo directoryInfo = new DirectoryInfo(
HttpContext.Current.Server.MapPath(directoryVirtualPath));
While it is possible to set HttpContext.Current during a unit test, I can't figure out how to make its .Server.MapPath(string directoryVirtualPath) return a non-null string. Since the DirectoryInfo(string) constructor throws an exception when passed a null argument, such a test will always fail.
What is the .NET team's recommendation for this? Do we have to unit test bundling configurations as part of integration tests or user acceptance tests?

Answer 1

I have some good news for you, for RTM we added a new static property on BundleTable to enable more unit tests:
public static Func<string, string> MapPathMethod;
Edit Updated with a test virtual path provider:
So you can do something like this:
public class TestVirtualPathProvider : VirtualPathProvider {
private string NormalizeVirtualPath(string virtualPath, bool isDirectory = false) {
if (!virtualPath.StartsWith("~")) {
virtualPath = "~" + virtualPath;
}
virtualPath = virtualPath.Replace('\\', '/');
// Normalize directories to always have an ending "/"
if (isDirectory && !virtualPath.EndsWith("/")) {
return virtualPath + "/";
}
return virtualPath;
}
// Files on disk (virtualPath -> file)
private Dictionary<string, VirtualFile> _fileMap = new Dictionary<string, VirtualFile>();
private Dictionary<string, VirtualFile> FileMap {
get { return _fileMap; }
}
public void AddFile(VirtualFile file) {
FileMap[NormalizeVirtualPath(file.VirtualPath)] = file;
}
private Dictionary<string, VirtualDirectory> _directoryMap = new Dictionary<string, VirtualDirectory>();
private Dictionary<string, VirtualDirectory> DirectoryMap {
get { return _directoryMap; }
}
public void AddDirectory(VirtualDirectory dir) {
DirectoryMap[NormalizeVirtualPath(dir.VirtualPath, isDirectory: true)] = dir;
}
public override bool FileExists(string virtualPath) {
return FileMap.ContainsKey(NormalizeVirtualPath(virtualPath));
}
public override bool DirectoryExists(string virtualDir) {
return DirectoryMap.ContainsKey(NormalizeVirtualPath(virtualDir, isDirectory: true));
}
public override VirtualFile GetFile(string virtualPath) {
return FileMap[NormalizeVirtualPath(virtualPath)];
}
public override VirtualDirectory GetDirectory(string virtualDir) {
return DirectoryMap[NormalizeVirtualPath(virtualDir, isDirectory: true)];
}
internal class TestVirtualFile : VirtualFile {
public TestVirtualFile(string virtualPath, string contents)
: base(virtualPath) {
Contents = contents;
}
public string Contents { get; set; }
public override Stream Open() {
return new MemoryStream(UTF8Encoding.Default.GetBytes(Contents));
}
}
internal class TestVirtualDirectory : VirtualDirectory {
public TestVirtualDirectory(string virtualPath)
: base(virtualPath) {
}
public List<VirtualFile> _directoryFiles = new List<VirtualFile>();
public List<VirtualFile> DirectoryFiles {
get {
return _directoryFiles;
}
}
public List<VirtualDirectory> _subDirs = new List<VirtualDirectory>();
public List<VirtualDirectory> SubDirectories {
get {
return _subDirs;
}
}
public override IEnumerable Files {
get {
return DirectoryFiles;
}
}
public override IEnumerable Children {
get { throw new NotImplementedException(); }
}
public override IEnumerable Directories {
get {
return SubDirectories;
}
}
}
And then write a unit test using that like so:
[TestMethod]
public void StyleBundleCustomVPPIncludeVersionSelectsTest() {
//Setup the vpp to contain the files/directories
TestVirtualPathProvider vpp = new TestVirtualPathProvider();
var directory = new TestVirtualPathProvider.TestVirtualDirectory("/dir/");
directory.DirectoryFiles.Add(new TestVirtualPathProvider.TestVirtualFile("/dir/style1.0.css", "correct"));
directory.DirectoryFiles.Add(new TestVirtualPathProvider.TestVirtualFile("/dir/style.css", "wrong"));
vpp.AddDirectory(directory);
// Setup the bundle
ScriptBundle bundle = new ScriptBundle("~/bundles/test");
bundle.Items.VirtualPathProvider = vpp;
bundle.Include("~/dir/style{version}.css");
// Verify the bundle repsonse
BundleContext context = SetupContext(bundle, vpp);
BundleResponse response = bundle.GetBundleResponse(context);
Assert.AreEqual(#"correct", response.Content);
}

Answer 2

In .Net 4.5 things have slightly changed. Here is a working version of the approved answer updated to accommodate these changes (I am using Autofac). Note the "GenerateBundleResponse" instead of "GetBundleResponse":
[Fact]
public void StyleBundleIncludesVersion()
{
//Setup the vpp to contain the files/directories
var vpp = new TestVirtualPathProvider();
var directory = new TestVirtualPathProvider.TestVirtualDirectory("/dir/");
directory.DirectoryFiles.Add(new TestVirtualPathProvider.TestVirtualFile("/dir/style1.0.css", "correct"));
directory.DirectoryFiles.Add(new TestVirtualPathProvider.TestVirtualFile("/dir/style.css", "wrong"));
vpp.AddDirectory(directory);
// Setup the bundle
var bundleCollection = new BundleCollection();
var bundle = new ScriptBundle("~/bundles/test");
BundleTable.VirtualPathProvider = vpp;
bundle.Include("~/dir/style{version}.css");
bundleCollection.Add(bundle);
var mockHttpContext = new Mock<HttpContextBase>();
// Verify the bundle repsonse
var context = new BundleContext(mockHttpContext.Object, bundleCollection, vpp.ToString());
var response = bundle.GenerateBundleResponse(context);
Assert.Equal(#"correct", response.Content);
}