DirectoryWatcherBase - SubscribeNullCallback

brian-dot-net · Feb 10, 2020 · 1dd3fff · 1dd3fff
1 parent 0b756e4
commit 1dd3fff
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diff --git a/projects/DirectoryWatcherSample/DirectoryWatcherSample.Core/DirectoryWatcherBase.cs b/projects/DirectoryWatcherSample/DirectoryWatcherSample.Core/DirectoryWatcherBase.cs
@@ -31,6 +31,11 @@ public IDisposable Subscribe(string file, Action<FileInfo> onUpdate)
                 throw new ArgumentNullException(nameof(file));
             }
 
+            if (onUpdate == null)
+            {
+                throw new ArgumentNullException(nameof(onUpdate));
+            }
+
             FileInfo fullPath = new FileInfo(Path.Combine(this.path, file));
             string key = fullPath.FullName;
             Action onDispose = () => this.subscriptions.TryRemove(key, out _);

diff --git a/projects/DirectoryWatcherSample/DirectoryWatcherSample.Test/DirectoryWatcherBaseTest.cs b/projects/DirectoryWatcherSample/DirectoryWatcherSample.Test/DirectoryWatcherBaseTest.cs
@@ -189,6 +189,17 @@ public void SubscribeNullFile()
             act.Should().Throw<ArgumentNullException>().Which.ParamName.Should().Be("file");
         }
 
+        [TestMethod]
+        public void SubscribeNullCallback()
+        {
+            DirectoryWatcherBase watcherBase = new FakeDirectoryWatcher(new DirectoryInfo(@"X:\root"));
+            Action<FileInfo> onUpdate = null;
+
+            Action act = () => watcherBase.Subscribe("file1.txt", onUpdate);
+
+            act.Should().Throw<ArgumentNullException>().Which.ParamName.Should().Be("onUpdate");
+        }
+
         private sealed class FakeDirectoryWatcher : DirectoryWatcherBase
         {
             public FakeDirectoryWatcher(DirectoryInfo path)