use Array.Empty (#6801)

src/contrib/cluster/Akka.Cluster.Metrics.Tests/MetricSpec.cs

@@ -74,16 +74,16 @@ public class NodeMetricSpec
         [Fact]
         public void NodeMetrics_Should_return_correct_result_for_2_same_nodes()
         {
-            new NodeMetrics(_node1, 0, new NodeMetrics.Types.Metric[0])
-                .SameAs(new NodeMetrics(_node1, 0, new NodeMetrics.Types.Metric[0]))
+            new NodeMetrics(_node1, 0, Array.Empty<NodeMetrics.Types.Metric>())
+                .SameAs(new NodeMetrics(_node1, 0, Array.Empty<NodeMetrics.Types.Metric>()))
                 .Should().BeTrue();
         }
 
         [Fact]
         public void NodeMetrics_Should_return_correct_result_for_2_not_same_nodes()
         {
-            new NodeMetrics(_node1, 0, new NodeMetrics.Types.Metric[0])
-                .SameAs(new NodeMetrics(_node2, 0, new NodeMetrics.Types.Metric[0]))
+            new NodeMetrics(_node1, 0, Array.Empty<NodeMetrics.Types.Metric>())
+                .SameAs(new NodeMetrics(_node2, 0, Array.Empty<NodeMetrics.Types.Metric>()))
                 .Should().BeFalse();
         }
 

src/contrib/cluster/Akka.Cluster.Metrics/Serialization/ClusterMetricsMessageSerializer.cs

@@ -54,8 +54,8 @@ public override byte[] ToBinary(object obj)
                 case MetricsGossipEnvelope m: return Compress(MetricsGossipEnvelopeToProto(m)); // TODO: Add compression here
                 case Metrics.AdaptiveLoadBalancingPool alb: return AdaptiveLoadBalancingPoolToBinary(alb);
                 case Metrics.MixMetricsSelector mms: return MixMetricsSelectorToBinary(mms);
-                case CpuMetricsSelector _: return new byte[0];
-                case MemoryMetricsSelector _: return new byte[0];
+                case CpuMetricsSelector _: return Array.Empty<byte>();
+                case MemoryMetricsSelector _: return Array.Empty<byte>();
                 default:
                     throw new ArgumentException($"Can't serialize object of type ${obj.GetType().Name} in [${GetType().Name}]");
             }

src/contrib/serializers/Akka.Serialization.Hyperion.Tests/HyperionSerializerSetupSpec.cs

@@ -63,7 +63,7 @@ public void Setup_should_be_converted_to_settings_correctly()
                     false, 
                     typeof(DummyTypesProvider), 
                     new Func<string, string>[] { s => $"{s}.." },
-                    new Surrogate[0],
+                    Array.Empty<Surrogate>(),
                     true);
             var appliedSettings = setup.ApplySettings(settings);
 

src/contrib/serializers/Akka.Serialization.Hyperion/HyperionSerializer.cs

@@ -313,7 +313,7 @@ public static HyperionSerializerSettings Create(Config config)
         /// <exception>Raised when `known-types-provider` type doesn't implement <see cref="IKnownTypesProvider"/> interface.</exception>
         [Obsolete]
         public HyperionSerializerSettings(bool preserveObjectReferences, bool versionTolerance, Type knownTypesProvider)
-            : this(preserveObjectReferences, versionTolerance, knownTypesProvider, new List<Func<string, string>>(), new Surrogate[0], true, DisabledTypeFilter.Instance)
+            : this(preserveObjectReferences, versionTolerance, knownTypesProvider, new List<Func<string, string>>(), Array.Empty<Surrogate>(), true, DisabledTypeFilter.Instance)
         { }
 
         /// <summary>
@@ -330,7 +330,7 @@ public HyperionSerializerSettings(
             bool versionTolerance, 
             Type knownTypesProvider, 
             IEnumerable<Func<string, string>> packageNameOverrides)
-            : this(preserveObjectReferences, versionTolerance, knownTypesProvider, packageNameOverrides, new Surrogate[0], true, DisabledTypeFilter.Instance)
+            : this(preserveObjectReferences, versionTolerance, knownTypesProvider, packageNameOverrides, Array.Empty<Surrogate>(), true, DisabledTypeFilter.Instance)
         { }
 
         /// <summary>

src/core/Akka.Cluster/SplitBrainResolver.cs

@@ -139,7 +139,7 @@ public IEnumerable<Member> Apply(NetworkPartitionContext context)
 
             if (remaining.Count < unreachable.Count) return context.Remaining;
             if (remaining.Count > unreachable.Count) return context.Unreachable;
-            if (remaining.IsEmpty && unreachable.IsEmpty) return new Member[0];
+            if (remaining.IsEmpty && unreachable.IsEmpty) return Array.Empty<Member>();
 
             // if the parts are of equal size the part containing the node with the lowest address is kept.
             var oldest = remaining.Union(unreachable).First();

src/core/Akka.Persistence.Query/PersistenceQuery.cs

@@ -62,7 +62,7 @@ private IReadJournalProvider CreateType(Type pluginType, object[] parameters)
             if (ctor != null) return (IReadJournalProvider)ctor.Invoke(new[] { parameters[0] });
 
             ctor = pluginType.GetConstructor(new Type[0]);
-            if (ctor != null) return (IReadJournalProvider)ctor.Invoke(new object[0]);
+            if (ctor != null) return (IReadJournalProvider)ctor.Invoke(Array.Empty<object>());
 
             throw new ArgumentException($"Unable to create read journal plugin instance type {pluginType}!");
         }

src/core/Akka.Persistence.TCK/Serialization/SnapshotStoreSerializationSpec.cs

@@ -95,7 +95,7 @@ public virtual void SnapshotStore_should_serialize_AtLeastOnceDeliverySnapshot_w
         {
             var probe = CreateTestProbe();
 
-            var unconfirmed = new UnconfirmedDelivery[0];
+            var unconfirmed = Array.Empty<UnconfirmedDelivery>();
             var atLeastOnceDeliverySnapshot = new AtLeastOnceDeliverySnapshot(13, unconfirmed);
 
             var metadata = new SnapshotMetadata(Pid, 2);

src/core/Akka.Remote.Tests/Serialization/MiscMessageSerializerSpec.cs

@@ -376,7 +376,7 @@ public void Serializer_must_reject_invalid_manifest()
         public void Serializer_must_reject_deserialization_with_invalid_manifest()
         {
             var serializer = new MiscMessageSerializer(Sys.AsInstanceOf<ExtendedActorSystem>());
-            Action comparison = () => serializer.FromBinary(new byte[0], "INVALID");
+            Action comparison = () => serializer.FromBinary(Array.Empty<byte>(), "INVALID");
             comparison.Should().Throw<SerializationException>();
         }
 

src/core/Akka.Remote.Tests/TransientSerializationErrorSpec.cs

@@ -111,7 +111,7 @@ public override byte[] ToBinary(object obj)
                     case ToBinaryIllegal _:
                         throw new ArgumentException();
                     default:
-                        return new byte[0];
+                        return Array.Empty<byte>();
                 }
             }
         }

src/core/Akka.Streams.Tests/Dsl/FlowIntersperseSpec.cs

@@ -107,7 +107,7 @@ public void A_Intersperse_must_surround_single_element_stream_with_start_and_end
         public void A_Intersperse_must_not_surround_empty_stream_with_null_start_and_stop()
         {
             var probe =
-                Source.From(new int[0])
+                Source.From(Array.Empty<int>())
                     .Select(x => x.ToString())
                     .Intersperse(",")
                     .RunWith(this.SinkProbe<string>(), Materializer);

src/core/Akka.Streams.Tests/Dsl/FlowSelectManySpec.cs

@@ -35,7 +35,7 @@ public FlowSelectManySpec(ITestOutputHelper output) : base(output)
         public async Task SelectMany_should_map_and_concat()
         {
             var script = Script.Create(
-                (new[] { 0 }, new int[0]),
+                (new[] { 0 }, Array.Empty<int>()),
                 (new[] { 1 }, new[] { 1 }),
                 (new[] { 2 }, new[] { 2, 2 }),
                 (new[] { 3 }, new[] { 3, 3, 3 }),

src/core/Akka.Streams.Tests/Dsl/FlowStatefulSelectManySpec.cs

@@ -37,7 +37,7 @@ public void A_StatefulSelectMany_must_work_in_happy_case()
             {
                 var phases = new[]
                 {
-                    ((ICollection<int>)new[] {2}, (ICollection<int>)new int[0]),
+                    ((ICollection<int>)new[] {2}, (ICollection<int>)Array.Empty<int>()),
                     ((ICollection<int>)new[] {1}, (ICollection<int>)new[] {1, 1}),
                     ((ICollection<int>)new[] {3}, (ICollection<int>)new[] {3}),
                     ((ICollection<int>)new[] {6}, (ICollection<int>)new[] {6, 6, 6})

src/core/Akka.Streams.Tests/Dsl/RetrySpec.cs

@@ -266,7 +266,7 @@ public void RetryConcat_should_concat_incremented_ints_and_modulo_3_incremented_
                 {
                     var s = (os + 1) % 3;
                     if (os < 42) return new[] { (os + 1, os + 1), (s, s) };
-                    if (os == 42) return new (int, int)[0];
+                    if (os == 42) return Array.Empty<(int, int)>();
                     return null;
                 }))
                 .ToMaterialized(this.SinkProbe<(Result<int>, int)>(), Keep.Both)

src/core/Akka.Streams.Tests/IO/InputStreamSinkSpec.cs

@@ -191,7 +191,7 @@ await this.AssertAllStagesStoppedAsync(() => {
 
                 Action(() => inputStream.Read(buf, -1, 2)).Should().Throw<ArgumentException>();
                 Action(() => inputStream.Read(buf, 0, 5)).Should().Throw<ArgumentException>();
-                Action(() => inputStream.Read(new byte[0], 0, 1)).Should().Throw<ArgumentException>();
+                Action(() => inputStream.Read(Array.Empty<byte>(), 0, 1)).Should().Throw<ArgumentException>();
                 Action(() => inputStream.Read(buf, 0, 0)).Should().Throw<ArgumentException>();
                 return Task.CompletedTask;
             }, _materializer);

src/core/Akka.Streams.Tests/Implementation/Fusing/GraphInterpreterSpecKit.cs

@@ -484,7 +484,7 @@ public PortTestSetup(ActorSystem system, bool chasing = false) : base(system)
                 var propagateStage = new EventPropagateStage();
 
                 var assembly = !chasing
-                    ? new GraphAssembly(new IGraphStageWithMaterializedValue<Shape, object>[0], new Attributes[0],
+                    ? new GraphAssembly(Array.Empty<IGraphStageWithMaterializedValue<Shape, object>>(), Array.Empty<Attributes>(),
                         new Inlet[] {null}, new[] {-1}, new Outlet[] {null}, new[] {-1})
                     : new GraphAssembly(new[] {propagateStage}, new[] {Attributes.None},
                         new Inlet[] {propagateStage.In, null}, new[] {0, -1}, new Outlet[] {null, propagateStage.Out},

src/core/Akka.Streams.Tests/Implementation/Fusing/InterpreterSpec.cs

@@ -96,7 +96,7 @@ public void Interpreter_should_implement_chain_of_maps_correctly()
         [Fact]
         public void Interpreter_should_work_with_only_boundary_ops()
         {
-            WithOneBoundedSetup(new IStage<int, int>[0],
+            WithOneBoundedSetup(Array.Empty<IStage<int, int>>(),
                 (lastEvents, upstream, downstream) =>
                 {
                     lastEvents().Should().BeEmpty();

src/core/Akka.Streams/Attributes.cs

@@ -283,7 +283,7 @@ public AfterDelay(TimeSpan delay, IStrategy strategy)
         /// <param name="attributes">TBD</param>
         public Attributes(params IAttribute[] attributes)
         {
-            _attributes = attributes ?? new IAttribute[0];
+            _attributes = attributes ?? Array.Empty<IAttribute>();
         }
 
         /// <summary>

src/core/Akka.Tests/Actor/PropsSpec.cs

@@ -61,7 +61,7 @@ public void Props_created_with_strategy_must_have_it_set()
         public void Props_created_with_null_type_must_throw()
         {
             Type missingType = null;
-            object[] args = new object[0];
+            object[] args = Array.Empty<object>();
             var argsEnumerable = Enumerable.Empty<object>();
             var defaultStrategy = SupervisorStrategy.DefaultStrategy;
             var defaultDeploy = Deploy.Local;

src/core/Akka.Tests/MatchHandler/CachedMatchCompilerTests.cs

@@ -21,7 +21,7 @@ public class CachedMatchCompilerTests
         public void When_compiling_first_time_correct_calls_are_made_to_MatchExpressionBuilder_and_PartialActionBuilder()
         {
             //Arrange
-            object[] argumentValues = new object[0];
+            object[] argumentValues = Array.Empty<object>();
             Expression<Func<object, bool>> lambdaExpression = _ => true;
             var matchExpressionBuilder = new DummyMatchExpressionBuilder()
             {
@@ -60,12 +60,11 @@ public void When_compiling_first_time_correct_calls_are_made_to_MatchExpressionB
         public void When_compiling_second_time_with_same_signature_the_cached_version_should_be_used()
         {
             //Arrange
-            object[] argumentValues = new object[0];
             Expression<Func<object, bool>> lambdaExpression = _ => true;
             var matchExpressionBuilder = new DummyMatchExpressionBuilder()
             {
-                BuildLambdaExpressionResult = new MatchExpressionBuilderResult(lambdaExpression, argumentValues),
-                CreateArgumentValuesArrayResult = argumentValues,
+                BuildLambdaExpressionResult = new MatchExpressionBuilderResult(lambdaExpression, Array.Empty<object>()),
+                CreateArgumentValuesArrayResult = Array.Empty<object>(),
             };
 
             Func<object, bool> deleg = _ => true;
@@ -95,7 +94,7 @@ public void When_compiling_second_time_with_same_signature_the_cached_version_sh
             //Assert
 
             AssertOneCall(to: matchExpressionBuilder.CreateArgumentValuesArrayCalls, withArgument: arguments, description: "CreateArgumentValuesArray");
-            AssertOneCall(to: partialActionBuilder.BuildCalls, description: "Build", check: i => ReferenceEquals(i.CompiledDelegate, deleg) && ReferenceEquals(i.DelegateArguments, argumentValues));
+            AssertOneCall(to: partialActionBuilder.BuildCalls, description: "Build", check: i => ReferenceEquals(i.CompiledDelegate, deleg) && ReferenceEquals(i.DelegateArguments, Array.Empty<object>()));
             Assert.Same(partialAction, resultPartialAction);
 
             AssertNoCall(to: matchExpressionBuilder.BuildLambdaExpressionCalls, description: "BuildLambdaExpression");

src/core/Akka.Tests/MatchHandler/MatchBuilderSignatureTests.cs

@@ -5,6 +5,7 @@
 // </copyright>
 //-----------------------------------------------------------------------
 
+using System;
 using Akka.Tools.MatchHandler;
 using Xunit;
 
@@ -16,7 +17,7 @@ public class MatchBuilderSignatureTests
         public void GetHashCode_should_return_same_value_for_empty_and_null_signatures()
         {
             var nullSignature = new MatchBuilderSignature(null);
-            var emptySignature = new MatchBuilderSignature(new object[0]);
+            var emptySignature = new MatchBuilderSignature(Array.Empty<object>());
 
             Assert.Equal(nullSignature.GetHashCode(), emptySignature.GetHashCode());
         }
@@ -83,7 +84,7 @@ public void GetHashCode_should_be_different_when_same_elements_but_fewer()
         [Fact]
         public void Equals_with_null_should_be_false()
         {
-            var signature = new MatchBuilderSignature(new object[0]);
+            var signature = new MatchBuilderSignature(Array.Empty<object>());
             Assert.False(signature.Equals((object)null));
             Assert.False(signature.Equals(null));
         }
@@ -92,15 +93,15 @@ public void Equals_with_null_should_be_false()
         [Fact]
         public void Equals_with_same_should_be_true()
         {
-            var signature = new MatchBuilderSignature(new object[0]);
+            var signature = new MatchBuilderSignature(Array.Empty<object>());
             Assert.True(signature.Equals((object)signature));
             Assert.True(signature.Equals(signature));
         }
 
         [Fact]
         public void Equals_with_different_type_should_be_false()
         {
-            var signature = new MatchBuilderSignature(new object[0]);
+            var signature = new MatchBuilderSignature(Array.Empty<object>());
             Assert.False(signature.Equals(new object()));
         }
 
@@ -116,7 +117,7 @@ public void Equals_with_two_null_element_signatures_should_be_true()
         public void Equals_with_one_null_element_signature_and_one_empty_element_signature_should_be_true()
         {
             var signature1 = new MatchBuilderSignature(null);
-            var signature2 = new MatchBuilderSignature(new object[0]);
+            var signature2 = new MatchBuilderSignature(Array.Empty<object>());
             Assert.True(signature1.Equals(signature2));
             Assert.True(signature2.Equals(signature1));
         }

src/core/Akka.Tests/MatchHandler/PartialActionBuilderTests.cs

@@ -22,7 +22,7 @@ public void Given_a_0_arguments_delegate_When_building_and_invoking_Then_the_sup
             object updatedValue = null;
             Func<object, bool> deleg = value => { updatedValue = value; return true; };
 
-            var partialAction = builder.Build<object>(new CompiledMatchHandlerWithArguments(deleg, new object[0]));
+            var partialAction = builder.Build<object>(new CompiledMatchHandlerWithArguments(deleg, Array.Empty<object>()));
             partialAction("value");
             Assert.Same(updatedValue, "value");
         }

src/core/Akka/Routing/RouterConfig.cs

@@ -147,7 +147,7 @@ public abstract class Group : RouterConfig, IEquatable<Group>
         protected Group(IEnumerable<string> paths, string routerDispatcher) : base(routerDispatcher)
         {
             // equivalent of turning the paths into an immutable sequence
-            InternalPaths = paths?.ToArray() ?? new string[0];
+            InternalPaths = paths?.ToArray() ?? Array.Empty<string>();
         }
 
         /// <summary>

src/examples/Cluster/Roles/Samples.Cluster.Transformation/Program.cs

@@ -24,9 +24,9 @@ static void Main(string[] args)
             _clusterConfig = section.AkkaConfig;
             LaunchBackend(new []{ "2551" });
             LaunchBackend(new[] { "2552" });
-            LaunchBackend(new string[0]);
-            LaunchFrontend(new string[0]);
-            LaunchFrontend(new string[0]);
+            LaunchBackend(Array.Empty<string>());
+            LaunchFrontend(Array.Empty<string>());
+            LaunchFrontend(Array.Empty<string>());
             //starting 2 frontend nodes and 3 backend nodes
             Console.WriteLine("Press any key to exit.");
             Console.ReadLine();