Update SA1010 tests for function pointers

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp9/SpacingRules/SA1010CSharp9UnitTests.cs

@@ -3,9 +3,42 @@
 
 namespace StyleCop.Analyzers.Test.CSharp9.SpacingRules
 {
+    using System.Threading;
+    using System.Threading.Tasks;
     using StyleCop.Analyzers.Test.CSharp8.SpacingRules;
+    using Xunit;
+    using static StyleCop.Analyzers.SpacingRules.SA1010OpeningSquareBracketsMustBeSpacedCorrectly;
+    using static StyleCop.Analyzers.Test.Verifiers.StyleCopCodeFixVerifier<
+        StyleCop.Analyzers.SpacingRules.SA1010OpeningSquareBracketsMustBeSpacedCorrectly,
+        StyleCop.Analyzers.SpacingRules.TokenSpacingCodeFixProvider>;
 
     public partial class SA1010CSharp9UnitTests : SA1010CSharp8UnitTests
     {
+        [Fact]
+        [WorkItem(3970, "https://github.com/DotNetAnalyzers/StyleCopAnalyzers/issues/3970")]
+        public async Task TestFunctionPointerCallingConventionBracketsAsync()
+        {
+            var testCode = @"public class TestClass
+{
+    private unsafe delegate* unmanaged{|#0:[|} Cdecl]<void> field1;
+    private unsafe delegate* unmanaged {|#1:[|}Cdecl]<void> field2;
+}
+";
+
+            var fixedCode = @"public class TestClass
+{
+    private unsafe delegate* unmanaged[Cdecl]<void> field1;
+    private unsafe delegate* unmanaged[Cdecl]<void> field2;
+}
+";
+
+            var expected = new[]
+            {
+                Diagnostic(DescriptorNotFollowed).WithLocation(0),
+                Diagnostic(DescriptorNotPreceded).WithLocation(1),
+            };
+
+            await VerifyCSharpFixAsync(testCode, expected, fixedCode, CancellationToken.None).ConfigureAwait(false);
+        }
     }
 }