Add unit test

Author: jairbubbles

LibGit2Sharp.Tests/BlobFixture.cs

@@ -15,6 +15,7 @@ public void CanGetBlobAsText()
             using (var repo = new Repository(path))
             {
                 var blob = repo.Lookup<Blob>("a8233120f6ad708f843d861ce2b7228ec4e3dec6");
+                Assert.False(blob.IsMissing);
 
                 var text = blob.GetContentText();
 
@@ -36,6 +37,7 @@ public void CanGetBlobAsFilteredText(string autocrlf, string expectedText)
                 repo.Config.Set("core.autocrlf", autocrlf);
 
                 var blob = repo.Lookup<Blob>("a8233120f6ad708f843d861ce2b7228ec4e3dec6");
+                Assert.False(blob.IsMissing);
 
                 var text = blob.GetContentText(new FilteringOptions("foo.txt"));
 
@@ -67,6 +69,7 @@ public void CanGetBlobAsTextWithVariousEncodings(string encodingName, int expect
                 var commit = repo.Commit("bom", Constants.Signature, Constants.Signature);
 
                 var blob = (Blob)commit.Tree[bomFile].Target;
+                Assert.False(blob.IsMissing);
                 Assert.Equal(expectedContentBytes, blob.Size);
                 using (var stream = blob.GetContentStream())
                 {
@@ -92,6 +95,7 @@ public void CanGetBlobSize()
             using (var repo = new Repository(path))
             {
                 var blob = repo.Lookup<Blob>("a8233120f6ad708f843d861ce2b7228ec4e3dec6");
+                Assert.False(blob.IsMissing);
                 Assert.Equal(10, blob.Size);
             }
         }
@@ -104,6 +108,7 @@ public void CanLookUpBlob()
             {
                 var blob = repo.Lookup<Blob>("a8233120f6ad708f843d861ce2b7228ec4e3dec6");
                 Assert.NotNull(blob);
+                Assert.False(blob.IsMissing);
             }
         }
 
@@ -114,6 +119,7 @@ public void CanReadBlobStream()
             using (var repo = new Repository(path))
             {
                 var blob = repo.Lookup<Blob>("a8233120f6ad708f843d861ce2b7228ec4e3dec6");
+                Assert.False(blob.IsMissing);
 
                 var contentStream = blob.GetContentStream();
                 Assert.Equal(blob.Size, contentStream.Length);
@@ -140,6 +146,7 @@ public void CanReadBlobFilteredStream(string autocrlf, string expectedContent)
                 repo.Config.Set("core.autocrlf", autocrlf);
 
                 var blob = repo.Lookup<Blob>("a8233120f6ad708f843d861ce2b7228ec4e3dec6");
+                Assert.False(blob.IsMissing);
 
                 var contentStream = blob.GetContentStream(new FilteringOptions("foo.txt"));
                 Assert.Equal(expectedContent.Length, contentStream.Length);
@@ -164,6 +171,7 @@ public void CanReadBlobFilteredStreamOfUnmodifiedBinary()
                 using (var stream = new MemoryStream(binaryContent))
                 {
                     Blob blob = repo.ObjectDatabase.CreateBlob(stream);
+                    Assert.False(blob.IsMissing);
 
                     using (var filtered = blob.GetContentStream(new FilteringOptions("foo.txt")))
                     {
@@ -196,6 +204,7 @@ public void CanStageAFileGeneratedFromABlobContentStream()
                 Assert.Equal("baae1fb3760a73481ced1fa03dc15614142c19ef", entry.Id.Sha);
 
                 var blob = repo.Lookup<Blob>(entry.Id.Sha);
+                Assert.False(blob.IsMissing);
 
                 using (Stream stream = blob.GetContentStream())
                 using (Stream file = File.OpenWrite(Path.Combine(repo.Info.WorkingDirectory, "small.fromblob.txt")))
@@ -217,10 +226,35 @@ public void CanTellIfTheBlobContentLooksLikeBinary()
             using (var repo = new Repository(path))
             {
                 var blob = repo.Lookup<Blob>("a8233120f6ad708f843d861ce2b7228ec4e3dec6");
+                Assert.False(blob.IsMissing);
                 Assert.False(blob.IsBinary);
             }
         }
 
+        [Fact]
+        public void CanTellIsABlobIsMissing()
+        {
+            string repoPath = SandboxBareTestRepo();
+
+            // Manually delete the objects directory to simulate a partial clone
+            Directory.Delete(Path.Combine(repoPath, "objects", "a8"), true);
+
+            using (var repo = new Repository(repoPath)) 
+            {
+                // Look for the commit that reference the blob which is now missing
+                var commit = repo.Lookup<Commit>("4a202b346bb0fb0db7eff3cffeb3c70babbd2045");
+                var blob = (Blob) commit.Tree["README"].Target;
+
+                Assert.Equal("a8233120f6ad708f843d861ce2b7228ec4e3dec6", blob.Sha);
+                Assert.NotNull(blob);
+                Assert.True(blob.IsMissing);
+                Assert.Throws<NotFoundException>(() => blob.Size);
+                Assert.Throws<NotFoundException>(() => blob.IsBinary);
+                Assert.Throws<NotFoundException>(() => blob.GetContentText());
+                Assert.Throws<NotFoundException>(() => blob.GetContentText(new FilteringOptions("foo.txt")));
+            }
+        }
+
         private static void SkipIfNotSupported(string autocrlf)
         {
             InconclusiveIf(() => autocrlf == "true" && Constants.IsRunningOnUnix, "Non-Windows does not support core.autocrlf = true");

LibGit2Sharp/Blob.cs

@@ -28,7 +28,7 @@ internal Blob(Repository repo, ObjectId id)
         {
             lazySize = GitObjectLazyGroup.Singleton(repo, id, Proxy.git_blob_rawsize);
             lazyIsBinary = GitObjectLazyGroup.Singleton(repo, id, Proxy.git_blob_is_binary);
-            lazyIsMissing = GitObjectLazyGroup.Singleton(repo, id, handle => handle == null);
+            lazyIsMissing = GitObjectLazyGroup.Singleton(repo, id, handle => handle == null, throwsIfMissing: false);
         }
 
         /// <summary>

LibGit2Sharp/Core/GitObjectLazyGroup.cs

@@ -18,20 +18,20 @@ protected override void EvaluateInternal(Action<ObjectHandle> evaluator)
             using (var osw = new ObjectSafeWrapper(id, repo.Handle))
             {
                 if (osw.ObjectPtr == null)
-                    throw new NotFoundException($"Object {id} is not available");
+                    throw new NotFoundException($"No valid git object identified by '{id}' exists in the repository.");
 
                 evaluator(osw.ObjectPtr);
             }
         }
 
-        public static ILazy<TResult> Singleton<TResult>(Repository repo, ObjectId id, Func<ObjectHandle, TResult> resultSelector)
+        public static ILazy<TResult> Singleton<TResult>(Repository repo, ObjectId id, Func<ObjectHandle, TResult> resultSelector, bool throwsIfMissing = true)
         {
             return Singleton(() =>
             {
                 using (var osw = new ObjectSafeWrapper(id, repo.Handle))
                 {
-                    if (osw.ObjectPtr == null)
-                        throw new NotFoundException($"Object {id} is not available");
+                    if (throwsIfMissing && osw.ObjectPtr == null)
+                        throw new NotFoundException($"No valid git object identified by '{id}' exists in the repository.");
 
                     return resultSelector(osw.ObjectPtr);
                 }