Update compilation context tests to expect correct language version

Author: dsplaisted

src/Tests/Microsoft.NET.Publish.Tests/GivenThatWeWantToPreserveCompilationContext.cs

@@ -70,6 +70,12 @@ public void It_publishes_the_project_with_a_refs_folder_and_correct_deps_file(st
             testAsset.Restore(Log, "TestApp");
 
             var appProjectDirectory = Path.Combine(testAsset.TestRoot, "TestApp");
+
+            var getValuesCommand = new GetValuesCommand(Log, appProjectDirectory, testProject.TargetFrameworks, "LangVersion");
+            getValuesCommand.Execute().Should().Pass();
+
+            var langVersion = getValuesCommand.GetValues().FirstOrDefault() ?? string.Empty;
+
             var publishCommand = new PublishCommand(Log, appProjectDirectory);
 
             publishCommand
@@ -114,7 +120,7 @@ public void It_publishes_the_project_with_a_refs_folder_and_correct_deps_file(st
                 }
 
                 dependencyContext.CompilationOptions.Defines.Should().BeEquivalentTo(expectedDefines);
-                dependencyContext.CompilationOptions.LanguageVersion.Should().BeOneOf("", "preview");
+                dependencyContext.CompilationOptions.LanguageVersion.Should().Be(langVersion);
                 dependencyContext.CompilationOptions.Platform.Should().Be("x86");
                 dependencyContext.CompilationOptions.Optimize.Should().Be(false);
                 dependencyContext.CompilationOptions.KeyFile.Should().Be("");