From 51f7fd5e83cc6bacf452e3abcb4074abf373ae2a Mon Sep 17 00:00:00 2001
From: Ivan Migalev <ivan.migalev@jetbrains.com>
Date: Tue, 28 Jan 2025 20:10:48 +0100
Subject: [PATCH] Lifetime: new equality model for Eternal and default values

---
 rd-net/Lifetimes/Lifetimes/Lifetime.cs        |  9 ++-
 .../Test.Lifetimes/Lifetimes/LifetimeTest.cs  | 72 +++++++++++++++----
 2 files changed, 64 insertions(+), 17 deletions(-)

diff --git a/rd-net/Lifetimes/Lifetimes/Lifetime.cs b/rd-net/Lifetimes/Lifetimes/Lifetime.cs
index f7d2c272..f3920f35 100644
--- a/rd-net/Lifetimes/Lifetimes/Lifetime.cs
+++ b/rd-net/Lifetimes/Lifetimes/Lifetime.cs
@@ -1165,7 +1165,7 @@ [PublicAPI] public Lifetime CreateTerminatedAfter(TimeSpan timeSpan, TaskSchedul
     
     public static bool operator ==(Lifetime left, Lifetime right) 
     {
-      return ReferenceEquals(left.Definition, right.Definition); 
+      return left.Equals(right);
     }
 
     public static bool operator !=(Lifetime left, Lifetime right)
@@ -1175,6 +1175,11 @@ [PublicAPI] public Lifetime CreateTerminatedAfter(TimeSpan timeSpan, TaskSchedul
     
     public bool Equals(Lifetime other)
     {
+      if (LogErrorIfLifetimeIsNotInitialized)
+      {
+        return ReferenceEquals(myDefinition, other.myDefinition);
+      }
+
       return ReferenceEquals(Definition, other.Definition);
     }
 
@@ -1186,7 +1191,7 @@ public override bool Equals(object? obj)
 
     public override int GetHashCode()
     {
-      return Definition.GetHashCode();
+      return myDefinition?.GetHashCode() ?? 0;
     }
 
     #endregion
diff --git a/rd-net/Test.Lifetimes/Lifetimes/LifetimeTest.cs b/rd-net/Test.Lifetimes/Lifetimes/LifetimeTest.cs
index eae8a71d..dfd4d670 100644
--- a/rd-net/Test.Lifetimes/Lifetimes/LifetimeTest.cs
+++ b/rd-net/Test.Lifetimes/Lifetimes/LifetimeTest.cs
@@ -1,9 +1,8 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using JetBrains.Core;
@@ -152,24 +151,59 @@ public void TestEternal()
     [Test]
     public void TestEquals()
     {
-      var old = Lifetime.LogErrorIfLifetimeIsNotInitialized;
-      Lifetime.LogErrorIfLifetimeIsNotInitialized = false;
+      var oldValue = Lifetime.LogErrorIfLifetimeIsNotInitialized;
       try
       {
-        Lifetime eternal = default;
-        Assert.AreEqual(Lifetime.Eternal, eternal);
-        Assert.AreEqual(Lifetime.Eternal, Lifetime.Eternal);
-        Assert.AreEqual(eternal, eternal);
-      
-        Assert.True(Lifetime.Eternal == eternal);
+        Lifetime.LogErrorIfLifetimeIsNotInitialized = false;
+        DoChecks(false);
 
-        Assert.AreNotEqual(Lifetime.Eternal, Lifetime.Terminated);
-        Assert.False(Lifetime.Eternal == Lifetime.Terminated);
-        Assert.False(eternal == Lifetime.Terminated);
+        Lifetime.LogErrorIfLifetimeIsNotInitialized = true;
+        DoChecks(true);
       }
       finally
       {
-        Lifetime.LogErrorIfLifetimeIsNotInitialized = old;
+        Lifetime.LogErrorIfLifetimeIsNotInitialized = oldValue;
+      }
+
+      [SuppressMessage("ReSharper", "EqualExpressionComparison")]
+      void DoChecks(bool newDefaultBehaviorFlag)
+      {
+        Assert.AreEqual(Lifetime.LogErrorIfLifetimeIsNotInitialized, newDefaultBehaviorFlag);
+
+        Lifetime defaultLifetime = default;
+
+        // Checks that are always true:
+        Assert.AreEqual(defaultLifetime, defaultLifetime);
+        Assert.AreEqual(Lifetime.Eternal, Lifetime.Eternal);
+        Assert.AreEqual(Lifetime.Terminated, Lifetime.Terminated);
+        Assert.AreNotEqual(Lifetime.Eternal, Lifetime.Terminated);
+        Assert.AreNotEqual(defaultLifetime, Lifetime.Terminated);
+
+        Assert.True(defaultLifetime == defaultLifetime);
+        Assert.True(Lifetime.Eternal == Lifetime.Eternal);
+        Assert.True(Lifetime.Terminated == Lifetime.Terminated);
+        Assert.False(Lifetime.Eternal == Lifetime.Terminated);
+        Assert.False(defaultLifetime == Lifetime.Terminated);
+
+        Assert.False(defaultLifetime != defaultLifetime);
+        Assert.False(Lifetime.Eternal != Lifetime.Eternal);
+        Assert.False(Lifetime.Terminated != Lifetime.Terminated);
+        Assert.True(Lifetime.Eternal != Lifetime.Terminated);
+        Assert.True(defaultLifetime != Lifetime.Terminated);
+
+        // Checks depending on the state of the flag:
+        if (newDefaultBehaviorFlag)
+        {
+          Assert.AreNotEqual(defaultLifetime, Lifetime.Eternal);
+          Assert.False(defaultLifetime == Lifetime.Eternal);
+          Assert.True(defaultLifetime != Lifetime.Eternal);
+        }
+        else
+        {
+          Assert.AreEqual(defaultLifetime, Lifetime.Eternal);
+          Assert.True(defaultLifetime == Lifetime.Eternal);
+          Assert.False(defaultLifetime != Lifetime.Eternal);
+        }
       }
     }
 
@@ -179,6 +213,14 @@ public void TestTerminated()
       Assert.True(Lifetime.Terminated.Status == LifetimeStatus.Terminated);
     }
 
+    [Test]
+    public void TestGetHashCode()
+    {
+      _ = Lifetime.Eternal.GetHashCode();
+      _ = Lifetime.Terminated.GetHashCode();
+      _ = ((Lifetime)default).GetHashCode();
+    }
+
 
     [Test]
     public void TestRecursiveTermination()
@@ -1147,7 +1189,7 @@ public void T020_DefineNestedOrder()
 
       Assert.IsFalse(flag, "Nested closed twice.");
 
-      CollectionAssert.AreEqual(System.Linq.Enumerable.Range(0, entries.Count).Reverse().ToArray(), entries, "Order FAIL.");
+      CollectionAssert.AreEqual(Enumerable.Range(0, entries.Count).Reverse().ToArray(), entries, "Order FAIL.");
       
     }