From d76f6ed1276969b2caa66f9fc34bd2070d1a0185 Mon Sep 17 00:00:00 2001
From: Matt Bird <matthew.bird@ticketer.co.uk>
Date: Wed, 9 Nov 2022 09:34:29 +0000
Subject: [PATCH] Better return types for lists that aren't really mutable

---
 .../WebController/ResultDtoExtensions.cs               |  2 +-
 src/FluentResults/Factories/ResultHelper.cs            |  6 +++---
 src/FluentResults/Results/Result.cs                    |  2 +-
 src/FluentResults/Results/ResultBase.cs                | 10 +++++-----
 4 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/FluentResults.Samples/WebController/ResultDtoExtensions.cs b/src/FluentResults.Samples/WebController/ResultDtoExtensions.cs
index 35fc3cf..b646033 100644
--- a/src/FluentResults.Samples/WebController/ResultDtoExtensions.cs
+++ b/src/FluentResults.Samples/WebController/ResultDtoExtensions.cs
@@ -13,7 +13,7 @@ public static ResultDto ToResultDto(this Result result)
             return new ResultDto(false, TransformErrors(result.Errors));
         }
 
-        private static IEnumerable<ErrorDto> TransformErrors(List<IError> errors)
+        private static IEnumerable<ErrorDto> TransformErrors(IEnumerable<IError> errors)
         {
             return errors.Select(TransformError);
         }
diff --git a/src/FluentResults/Factories/ResultHelper.cs b/src/FluentResults/Factories/ResultHelper.cs
index 6c6d039..b523a8d 100644
--- a/src/FluentResults/Factories/ResultHelper.cs
+++ b/src/FluentResults/Factories/ResultHelper.cs
@@ -27,7 +27,7 @@ public static Result<IEnumerable<TValue>> MergeWithValue<TValue>(
         }
 
         public static bool HasError<TError>(
-            List<IError> errors,
+            IEnumerable<IError> errors,
             Func<TError, bool> predicate,
             out IEnumerable<TError> result)
             where TError : IError
@@ -53,7 +53,7 @@ public static bool HasError<TError>(
         }
 
         public static bool HasException<TException>(
-            List<IError> errors,
+            IEnumerable<IError> errors,
             Func<TException, bool> predicate,
             out IEnumerable<IError> result)
             where TException : Exception
@@ -83,7 +83,7 @@ public static bool HasException<TException>(
         }
 
         public static bool HasSuccess<TSuccess>(
-            List<ISuccess> successes, 
+            IEnumerable<ISuccess> successes, 
             Func<TSuccess, bool> predicate,
             out IEnumerable<TSuccess> result) where TSuccess : ISuccess
         {
diff --git a/src/FluentResults/Results/Result.cs b/src/FluentResults/Results/Result.cs
index 652708e..eef2098 100644
--- a/src/FluentResults/Results/Result.cs
+++ b/src/FluentResults/Results/Result.cs
@@ -497,7 +497,7 @@ public void Deconstruct(out bool isSuccess, out bool isFailed, out TValue value,
             isSuccess = IsSuccess;
             isFailed = IsFailed;
             value = IsSuccess ? Value : default;
-            errors = IsFailed ? Errors : default;
+            errors = IsFailed ? Errors.ToList() : default;
         }
 
         private void ThrowIfFailed()
diff --git a/src/FluentResults/Results/ResultBase.cs b/src/FluentResults/Results/ResultBase.cs
index e0b23df..98afdfb 100644
--- a/src/FluentResults/Results/ResultBase.cs
+++ b/src/FluentResults/Results/ResultBase.cs
@@ -26,12 +26,12 @@ public interface IResultBase
         /// <summary>
         /// Get all errors
         /// </summary>
-        List<IError> Errors { get; }
+        IReadOnlyList<IError> Errors { get; }
 
         /// <summary>
         /// Get all successes
         /// </summary>
-        List<ISuccess> Successes { get; }
+        IReadOnlyList<ISuccess> Successes { get; }
     }
 
     public abstract class ResultBase : IResultBase
@@ -54,12 +54,12 @@ public abstract class ResultBase : IResultBase
         /// <summary>
         /// <inheritdoc/>
         /// </summary>
-        public List<IError> Errors => Reasons.OfType<IError>().ToList();
+        public IReadOnlyList<IError> Errors => Reasons.OfType<IError>().ToList().AsReadOnly();
 
         /// <summary>
         /// <inheritdoc/>
         /// </summary>
-        public List<ISuccess> Successes => Reasons.OfType<ISuccess>().ToList();
+        public IReadOnlyList<ISuccess> Successes => Reasons.OfType<ISuccess>().ToList().AsReadOnly();
 
         protected ResultBase()
         {
@@ -226,7 +226,7 @@ public void Deconstruct(out bool isSuccess, out bool isFailed, out List<IError>
         {
             isSuccess = IsSuccess;
             isFailed = IsFailed;
-            errors = IsFailed ? Errors : default;
+            errors = IsFailed ? Errors.ToList() : default;
         }
     }