Add a test to confirm that frozen partial projects have different ver…

…sions

src/Workspaces/CoreTest/SolutionTests/SolutionTests.cs

@@ -2566,6 +2566,31 @@ public void TestProjectWithBrokenCrossLanguageReferenceHasIncompleteReferences()
             Assert.Empty(project2.GetCompilationAsync().Result.ExternalReferences);
         }
 
+        [Fact]
+        public async Task TestFrozenPartialProjectHasDifferentSemanticVersions()
+        {
+            using var workspace = CreateWorkspaceWithPartalSemantics();
+            var project = workspace.CurrentSolution.AddProject("CSharpProject", "CSharpProject", LanguageNames.CSharp);
+            project = project.AddDocument("Extra.cs", SourceText.From("class Extra { }")).Project;
+
+            var documentToFreeze = project.AddDocument("DocumentToFreeze.cs", SourceText.From(""));
+            var frozenDocument = documentToFreeze.WithFrozenPartialSemantics(CancellationToken.None);
+
+            // Because we had no compilation produced yet, we expect that only the DocumentToFreeze is in the compilation
+            Assert.NotSame(frozenDocument, documentToFreeze);
+            var tree = Assert.Single((await frozenDocument.Project.GetCompilationAsync()).SyntaxTrees);
+            Assert.Equal("DocumentToFreeze.cs", tree.FilePath);
+
+            // Versions should be different
+            Assert.NotEqual(
+                await documentToFreeze.Project.GetDependentSemanticVersionAsync(),
+                await frozenDocument.Project.GetDependentSemanticVersionAsync());
+
+            Assert.NotEqual(
+                await documentToFreeze.Project.GetSemanticVersionAsync(),
+                await frozenDocument.Project.GetSemanticVersionAsync());
+        }
+
         [Fact]
         public void TestFrozenPartialProjectAlwaysIsIncomplete()
         {