test: add guardian process tests

tests/Proto.Actor.Tests/GuardianProcessTests.cs

@@ -0,0 +1,93 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Proto.Mailbox;
+using Xunit;
+
+namespace Proto.Tests;
+
+public class GuardianProcessTests
+{
+    private class NoopStrategy : ISupervisorStrategy
+    {
+        public void HandleFailure(ISupervisor supervisor, PID child, RestartStatistics rs, Exception reason, object? message)
+        {
+        }
+    }
+
+    private class RecordingProcess : Process
+    {
+        public List<SystemMessage> Messages { get; } = new();
+
+        public RecordingProcess(ActorSystem system) : base(system)
+        {
+        }
+
+        protected internal override void SendUserMessage(PID pid, object message)
+        {
+        }
+
+        protected internal override void SendSystemMessage(PID pid, SystemMessage message)
+        {
+            Messages.Add(message);
+        }
+    }
+
+    [Fact]
+    public async Task Given_Guardian_SendUserMessageShouldThrow()
+    {
+        var system = new ActorSystem();
+        await using var _ = system;
+        var guardian = new GuardianProcess(system, new NoopStrategy());
+
+        Assert.Throws<InvalidOperationException>(() => guardian.SendUserMessage(guardian.Pid, "hello"));
+    }
+
+    [Fact]
+    public async Task Given_Guardian_RestartChildrenShouldSendRestartMessage()
+    {
+        var system = new ActorSystem();
+        await using var _ = system;
+        var guardian = new GuardianProcess(system, new NoopStrategy());
+        var child1 = new RecordingProcess(system);
+        var child2 = new RecordingProcess(system);
+        var (pid1, _) = system.ProcessRegistry.TryAdd(Guid.NewGuid().ToString(), child1);
+        var (pid2, _) = system.ProcessRegistry.TryAdd(Guid.NewGuid().ToString(), child2);
+        var reason = new Exception("boom");
+
+        guardian.RestartChildren(reason, pid1, pid2);
+
+        var msg1 = Assert.IsType<Restart>(Assert.Single(child1.Messages));
+        var msg2 = Assert.IsType<Restart>(Assert.Single(child2.Messages));
+        Assert.Same(reason, msg1.Reason);
+        Assert.Same(reason, msg2.Reason);
+    }
+
+    [Fact]
+    public async Task Given_Guardian_StopChildrenShouldSendStopMessage()
+    {
+        var system = new ActorSystem();
+        await using var _ = system;
+        var guardian = new GuardianProcess(system, new NoopStrategy());
+        var child1 = new RecordingProcess(system);
+        var child2 = new RecordingProcess(system);
+        var (pid1, _) = system.ProcessRegistry.TryAdd(Guid.NewGuid().ToString(), child1);
+        var (pid2, _) = system.ProcessRegistry.TryAdd(Guid.NewGuid().ToString(), child2);
+
+        guardian.StopChildren(pid1, pid2);
+
+        Assert.IsType<Stop>(Assert.Single(child1.Messages));
+        Assert.IsType<Stop>(Assert.Single(child2.Messages));
+    }
+
+    [Fact]
+    public async Task Given_Guardian_EscalateFailureShouldThrow()
+    {
+        var system = new ActorSystem();
+        await using var _ = system;
+        var guardian = new GuardianProcess(system, new NoopStrategy());
+
+        Assert.Throws<InvalidOperationException>(() => guardian.EscalateFailure(new Exception(), null));
+    }
+}
+