Support required properties (#2579)

* Support required properties

* Remove !

Author: aelij

src/BenchmarkDotNet/Code/CodeGenerator.cs

@@ -56,6 +56,7 @@ internal static string Generate(BuildPartition buildPartition)
                     .Replace("$OverheadImplementation$", provider.OverheadImplementation)
                     .Replace("$ConsumeField$", provider.ConsumeField)
                     .Replace("$JobSetDefinition$", GetJobsSetDefinition(benchmark))
+                    .Replace("$ParamsInitializer$", GetParamsInitializer(benchmark))
                     .Replace("$ParamsContent$", GetParamsContent(benchmark))
                     .Replace("$ArgumentsDefinition$", GetArgumentsDefinition(benchmark))
                     .Replace("$DeclareArgumentFields$", GetDeclareArgumentFields(benchmark))
@@ -186,7 +187,15 @@ private static DeclarationsProvider GetDeclarationsProvider(Descriptor descripto
             return new NonVoidDeclarationsProvider(descriptor);
         }
 
+        private static string GetParamsInitializer(BenchmarkCase benchmarkCase)
+            => string.Join(
+                ", ",
+                benchmarkCase.Parameters.Items
+                    .Where(parameter => !parameter.IsArgument && !parameter.IsStatic)
+                    .Select(parameter => $"{parameter.Name} = default"));
+
         // internal for tests
+
         internal static string GetParamsContent(BenchmarkCase benchmarkCase)
             => string.Join(
                 string.Empty,

src/BenchmarkDotNet/Templates/BenchmarkType.txt

@@ -3,7 +3,7 @@
     {
         public static void Run(BenchmarkDotNet.Engines.IHost host, System.String benchmarkName)
         {
-            BenchmarkDotNet.Autogenerated.Runnable_$ID$ instance = new BenchmarkDotNet.Autogenerated.Runnable_$ID$(); // do NOT change name "instance" (used in SmartParamameter)
+            BenchmarkDotNet.Autogenerated.Runnable_$ID$ instance = new BenchmarkDotNet.Autogenerated.Runnable_$ID$ { $ParamsInitializer$ }; // do NOT change name "instance" (used in SmartParamameter)
             $ParamsContent$
 
             host.WriteLine();

tests/BenchmarkDotNet.IntegrationTests/ParamsTests.cs

@@ -217,5 +217,28 @@ public void Test()
                     throw new ArgumentException($"{nameof(StaticParamProperty)} has wrong value: {StaticParamProperty}!");
             }
         }
+
+#if NET8_0_OR_GREATER
+        [Fact]
+        public void ParamsSupportRequiredProperty()
+        {
+            var summary = CanExecute<ParamsTestRequiredProperty>();
+            var standardOutput = GetCombinedStandardOutput(summary);
+
+            foreach (var param in new[] { "a", "b" })
+            {
+                Assert.Contains($"// ### New Parameter {param} ###", standardOutput);
+            }
+        }
+
+        public class ParamsTestRequiredProperty
+        {
+            [Params("a", "b")]
+            public required string ParamProperty { get; set; }
+
+            [Benchmark]
+            public void Benchmark() => Console.WriteLine($"// ### New Parameter {ParamProperty} ###");
+        }
+#endif
     }
 }