Make assertion more informative

src/EditorFeatures/DiagnosticsTestUtilities/CodeActions/AbstractCodeActionOrUserDiagnosticTest.cs

@@ -260,7 +260,8 @@ private TestParameters WithScriptOptions(TestParameters parameters)
             using (var workspace = CreateWorkspaceFromOptions(initialMarkup, parameters))
             {
                 var (actions, _) = await GetCodeActionsAsync(workspace, parameters);
-                Assert.True(actions.Length == 0, "An action was offered when none was expected");
+                var offeredActions = Environment.NewLine + string.Join(Environment.NewLine, actions.Select(action => action.Title));
+                Assert.True(actions.Length == 0, "An action was offered when none was expected. Offered actions:" + offeredActions);
             }
         }