Watch external dependent projects correctly

Author: BrennanConroy

src/Microsoft.Framework.Runtime.Compilation.DesignTime/DesignTimeHostCompiler.cs

@@ -13,10 +13,12 @@ public class DesignTimeHostCompiler : IDesignTimeHostCompiler
         private readonly IApplicationShutdown _shutdown;
         private readonly ConcurrentDictionary<int, TaskCompletionSource<CompileResponse>> _compileResponses = new ConcurrentDictionary<int, TaskCompletionSource<CompileResponse>>();
         private readonly TaskCompletionSource<Dictionary<string, int>> _projectContexts = new TaskCompletionSource<Dictionary<string, int>>();
+        private readonly IFileWatcher _watcher;
 
         public DesignTimeHostCompiler(IApplicationShutdown shutdown, IFileWatcher watcher, Stream stream)
         {
             _shutdown = shutdown;
+            _watcher = watcher;
             _queue = new ProcessingQueue(stream);
             _queue.ProjectCompiled += OnProjectCompiled;
             _queue.ProjectsInitialized += ProjectContextsInitialized;
@@ -87,6 +89,8 @@ public async Task<CompileResponse> Compile(string projectPath, ILibraryKey libra
                 ContextId = contextId
             });
 
+            _watcher.WatchProject(projectPath);
+
             var task = _compileResponses.GetOrAdd(contextId, _ => new TaskCompletionSource<CompileResponse>()).Task;
             return await task.ConfigureAwait(false);
         }

src/Microsoft.Framework.Runtime.Sources/Impl/DependencyInjection/ServiceProvider.cs

@@ -39,6 +39,22 @@ public void Add(Type type, object instance, bool includeInManifest)
             };
         }
 
+        public bool TryAdd(Type type, object instance)
+        {
+            return TryAdd(type, instance, includeInManifest: true);
+        }
+
+        public bool TryAdd(Type type, object instance, bool includeInManifest)
+        {
+            if (GetService(type) == null)
+            {
+                Add(type, instance, includeInManifest);
+                return true;
+            }
+
+            return false;
+        }
+
         public object GetService(Type serviceType)
         {
             ServiceEntry entry;

src/Microsoft.Framework.Runtime/ApplicationHostContext.cs

@@ -108,8 +108,8 @@ public ApplicationHostContext(IServiceProvider serviceProvider,
 
             // Default services
             _serviceProvider.Add(typeof(IApplicationEnvironment), new ApplicationEnvironment(Project, targetFramework, configuration));
-            _serviceProvider.Add(typeof(IFileWatcher), NoopWatcher.Instance);
             _serviceProvider.Add(typeof(ILibraryManager), LibraryManager);
+            _serviceProvider.TryAdd(typeof(IFileWatcher), NoopWatcher.Instance);
 
             // Not exposed to the application layer
             _serviceProvider.Add(typeof(ILibraryExportProvider), LibraryExportProvider, includeInManifest: false);