From 950775b65093e22ce209c947bf9da71b17ad7387 Mon Sep 17 00:00:00 2001
From: Austin Drenski <austin@austindrenski.io>
Date: Wed, 17 Jan 2024 13:22:04 -0500
Subject: [PATCH] fix: Fix ArgumentOutOfRangeException for empty hooks (#187)

Signed-off-by: Austin Drenski <austin@austindrenski.io>
---
 src/OpenFeature/Api.cs                        | 21 ++++++++++++++++++-
 src/OpenFeature/OpenFeatureClient.cs          | 21 ++++++++++++++++++-
 .../OpenFeature.Tests/OpenFeatureHookTests.cs |  7 +++++++
 3 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/src/OpenFeature/Api.cs b/src/OpenFeature/Api.cs
index 8d0e22f5..440242da 100644
--- a/src/OpenFeature/Api.cs
+++ b/src/OpenFeature/Api.cs
@@ -127,7 +127,26 @@ public FeatureClient GetClient(string name = null, string version = null, ILogge
         /// </para>
         /// </summary>
         /// <param name="hooks">A list of <see cref="Hook"/></param>
-        public void AddHooks(IEnumerable<Hook> hooks) => this._hooks.PushRange(hooks.ToArray());
+        public void AddHooks(IEnumerable<Hook> hooks)
+#if NET7_0_OR_GREATER
+            => this._hooks.PushRange(hooks as Hook[] ?? hooks.ToArray());
+#else
+        {
+            // See: https://github.com/dotnet/runtime/issues/62121
+            if (hooks is Hook[] array)
+            {
+                if (array.Length > 0)
+                    this._hooks.PushRange(array);
+
+                return;
+            }
+
+            array = hooks.ToArray();
+
+            if (array.Length > 0)
+                this._hooks.PushRange(array);
+        }
+#endif
 
         /// <summary>
         /// Adds a hook to global hooks list
diff --git a/src/OpenFeature/OpenFeatureClient.cs b/src/OpenFeature/OpenFeatureClient.cs
index 9ea9b13a..d979dae1 100644
--- a/src/OpenFeature/OpenFeatureClient.cs
+++ b/src/OpenFeature/OpenFeatureClient.cs
@@ -106,7 +106,26 @@ public void RemoveHandler(ProviderEventTypes type, EventHandlerDelegate handler)
         }
 
         /// <inheritdoc />
-        public void AddHooks(IEnumerable<Hook> hooks) => this._hooks.PushRange(hooks.ToArray());
+        public void AddHooks(IEnumerable<Hook> hooks)
+#if NET7_0_OR_GREATER
+            => this._hooks.PushRange(hooks as Hook[] ?? hooks.ToArray());
+#else
+        {
+            // See: https://github.com/dotnet/runtime/issues/62121
+            if (hooks is Hook[] array)
+            {
+                if (array.Length > 0)
+                    this._hooks.PushRange(array);
+
+                return;
+            }
+
+            array = hooks.ToArray();
+
+            if (array.Length > 0)
+                this._hooks.PushRange(array);
+        }
+#endif
 
         /// <inheritdoc />
         public IEnumerable<Hook> GetHooks() => this._hooks.Reverse();
diff --git a/test/OpenFeature.Tests/OpenFeatureHookTests.cs b/test/OpenFeature.Tests/OpenFeatureHookTests.cs
index a4810c04..b3aee4d8 100644
--- a/test/OpenFeature.Tests/OpenFeatureHookTests.cs
+++ b/test/OpenFeature.Tests/OpenFeatureHookTests.cs
@@ -553,5 +553,12 @@ public async Task When_Error_Occurs_In_After_Hook_Should_Invoke_Error_Hook()
 
             await featureProvider.DidNotReceive().ResolveBooleanValue("test", false, Arg.Any<EvaluationContext>());
         }
+
+        [Fact]
+        public void Add_hooks_should_accept_empty_enumerable()
+        {
+            Api.Instance.ClearHooks();
+            Api.Instance.AddHooks(Enumerable.Empty<Hook>());
+        }
     }
 }