Slightly refactor code to make it look fresh

.editorconfig

@@ -17,3 +17,8 @@ dotnet_style_qualification_for_field = false:suggestion
 dotnet_style_qualification_for_property = false:suggestion
 dotnet_style_qualification_for_method = false:suggestion
 dotnet_style_qualification_for_event = false:suggestion
+
+# ReSharper properties
+resharper_int_align_switch_expressions = true
+resharper_keep_existing_invocation_parens_arrangement = false
+resharper_space_within_single_line_array_initializer_braces = true

src/NSubstitute/Callback.cs

@@ -72,7 +72,7 @@ public static Callback AlwaysThrow<TException>(Func<CallInfo, TException> throwT
         /// <returns></returns>
         public static Callback AlwaysThrow<TException>(TException exception) where TException : Exception
         {
-            return AlwaysThrow(info => exception);
+            return AlwaysThrow(_ => exception);
         }
 
         protected static Action<CallInfo> ToCallback<TException>(Func<CallInfo, TException> throwThis)
@@ -93,12 +93,12 @@ protected void AddCallback(Action<CallInfo> doThis)
 
         protected void SetAlwaysDo(Action<CallInfo> always)
         {
-            alwaysDo = always == null ? x => { } :  always;
+            alwaysDo = always ?? (_ => { });
         }
 
         protected void SetKeepDoing(Action<CallInfo> keep)
         {
-            keepDoing = keep == null ? x => { } :  keep;
+            keepDoing = keep ?? (_ => { });
         }
 
         public void Call(CallInfo callInfo)

src/NSubstitute/Callbacks/ConfiguredCallback.cs

@@ -13,8 +13,6 @@ internal ConfiguredCallback() { }
         /// <summary>
         /// Perform this action once in chain of called callbacks.
         /// </summary>
-        /// <param name="doThis"></param>
-        /// <returns></returns>
         public ConfiguredCallback Then(Action<CallInfo> doThis)
         {
             AddCallback(doThis);
@@ -24,8 +22,6 @@ public ConfiguredCallback Then(Action<CallInfo> doThis)
         /// <summary>
         /// Keep doing this action after the other callbacks have run.
         /// </summary>
-        /// <param name="doThis"></param>
-        /// <returns></returns>
         public EndCallbackChain ThenKeepDoing(Action<CallInfo> doThis)
         {
             SetKeepDoing(doThis);
@@ -35,31 +31,20 @@ public EndCallbackChain ThenKeepDoing(Action<CallInfo> doThis)
         /// <summary>
         /// Keep throwing this exception after the other callbacks have run.
         /// </summary>
-        /// <typeparam name="TException"></typeparam>
-        /// <param name="throwThis"></param>
-        /// <returns></returns>
-        public EndCallbackChain ThenKeepThrowing<TException>(Func<CallInfo, TException> throwThis) where TException : Exception
-        {
-            return ThenKeepDoing(ToCallback(throwThis));
-        }
+        public EndCallbackChain ThenKeepThrowing<TException>(Func<CallInfo, TException> throwThis) where TException : Exception =>
+            ThenKeepDoing(ToCallback(throwThis));
 
         /// <summary>
         /// Keep throwing this exception after the other callbacks have run.
         /// </summary>
-        /// <typeparam name="TException"></typeparam>
-        /// <param name="throwThis"></param>
-        /// <returns></returns>
-        public EndCallbackChain ThenKeepThrowing<TException>(TException throwThis) where TException : Exception
-        {
-            return ThenKeepThrowing(info => throwThis);
-        }
+        public EndCallbackChain ThenKeepThrowing<TException>(TException throwThis) where TException : Exception =>
+            ThenKeepThrowing(info => throwThis);
 
         /// <summary>
         /// Throw exception returned by function once when called in a chain of callbacks.
         /// </summary>
         /// <typeparam name="TException">The type of the exception</typeparam>
         /// <param name="throwThis">Produce the exception to throw for a CallInfo</param>
-        /// <returns></returns>
         public ConfiguredCallback ThenThrow<TException>(Func<CallInfo, TException> throwThis) where TException : Exception
         {
             AddCallback(ToCallback(throwThis));
@@ -71,11 +56,8 @@ public ConfiguredCallback ThenThrow<TException>(Func<CallInfo, TException> throw
         /// </summary>
         /// <typeparam name="TException">The type of the exception</typeparam>
         /// <param name="exception">The exception to throw</param>
-        /// <returns></returns>
-        public ConfiguredCallback ThenThrow<TException>(TException exception) where TException : Exception
-        {
-            return ThenThrow(ci => exception);
-        }
+        public ConfiguredCallback ThenThrow<TException>(TException exception) where TException : Exception =>
+            ThenThrow(_ => exception);
     }
 
     public class EndCallbackChain : Callback
@@ -86,7 +68,6 @@ internal EndCallbackChain() { }
         /// Perform the given action for every call.
         /// </summary>
         /// <param name="doThis">The action to perform for every call</param>
-        /// <returns></returns>
         public Callback AndAlways(Action<CallInfo> doThis)
         {
             SetAlwaysDo(doThis);

src/NSubstitute/Core/Argument.cs

@@ -22,7 +22,7 @@ public Argument(Type declaredType, Func<object?> getValue, Action<object?> setVa
 
         public Argument(ICall call, int argIndex)
         {
-            _call = call ?? throw new ArgumentNullException(nameof(call));
+            _call = call;
             _argIndex = argIndex;
         }
 
@@ -48,24 +48,16 @@ public object? Value
 
         public Type ActualType => Value == null ? DeclaredType : Value.GetType();
 
-        public bool IsDeclaredTypeEqualToOrByRefVersionOf(Type type)
-        {
-            return AsNonByRefType(DeclaredType) == type;
-        }
+        public bool IsDeclaredTypeEqualToOrByRefVersionOf(Type type) =>
+            AsNonByRefType(DeclaredType) == type;
 
-        public bool IsValueAssignableTo(Type type)
-        {
-            return type.IsAssignableFrom(AsNonByRefType(ActualType));
-        }
+        public bool IsValueAssignableTo(Type type) =>
+            type.IsAssignableFrom(AsNonByRefType(ActualType));
 
-        public bool CanSetValueWithInstanceOf(Type type)
-        {
-            return AsNonByRefType(DeclaredType).IsAssignableFrom(type);
-        }
+        public bool CanSetValueWithInstanceOf(Type type) =>
+            AsNonByRefType(DeclaredType).IsAssignableFrom(type);
 
-        private static Type AsNonByRefType(Type type)
-        {
-            return type.IsByRef ? type.GetElementType()! : type;
-        }
+        private static Type AsNonByRefType(Type type) =>
+            type.IsByRef ? type.GetElementType()! : type;
     }
 }

src/NSubstitute/Core/Arguments/ArgumentFormatter.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Globalization;
 using System.Reflection;
 
 namespace NSubstitute.Core.Arguments
@@ -16,20 +15,16 @@ public string Format(object? argument, bool highlight)
 
         private string Format(object? arg)
         {
-            switch (arg)
+            return arg switch
             {
-                case null:
-                    return "<null>";
+                null                                 => "<null>",
+                string str                           => $"\"{str}\"",
+                { } obj when HasDefaultToString(obj) => arg.GetType().GetNonMangledTypeName(),
+                _                                    => arg.ToString() ?? string.Empty
+            };
 
-                case string str:
-                    return string.Format(CultureInfo.InvariantCulture, "\"{0}\"", str);
-
-                case object obj when obj.GetType().GetMethod(nameof(ToString), Type.EmptyTypes)!.DeclaringType == typeof(object):
-                    return arg.GetType().GetNonMangledTypeName();
-
-                default:
-                    return arg.ToString() ?? string.Empty;
-            }
-       }
+            static bool HasDefaultToString(object obj)
+                => obj.GetType().GetMethod(nameof(ToString), Type.EmptyTypes)!.DeclaringType == typeof(object);
+        }
     }
 }

src/NSubstitute/Core/Arguments/ArgumentMatchInfo.cs

@@ -11,9 +11,9 @@ public ArgumentMatchInfo(int index, object? argument, IArgumentSpecification spe
 
         private readonly object? _argument;
         private readonly IArgumentSpecification _specification;
-        public int Index { get; private set; }
+        public int Index { get; }
 
-        public bool IsMatch { get { return _specification.IsSatisfiedBy(_argument); } }
+        public bool IsMatch => _specification.IsSatisfiedBy(_argument);
 
         public string DescribeNonMatch()
         {

src/NSubstitute/Core/Arguments/ArgumentMatcher.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Diagnostics.CodeAnalysis;
+using NSubstitute.Exceptions;
 
 namespace NSubstitute.Core.Arguments
 {
@@ -13,28 +14,20 @@ public static class ArgumentMatcher
         {
             if (argumentMatcher == null) throw new ArgumentNullException(nameof(argumentMatcher));
 
-            IArgumentMatcher nonGenericMatcher;
-            if (argumentMatcher is IDescribeNonMatches)
+            IArgumentMatcher nonGenericMatcher = argumentMatcher switch
             {
-                nonGenericMatcher = new GenericToNonGenericMatcherProxyWithDescribe<T>(argumentMatcher);
-            }
-            else
-            {
-                nonGenericMatcher = new GenericToNonGenericMatcherProxy<T>(argumentMatcher);
-            }
+                IDescribeNonMatches => new GenericToNonGenericMatcherProxyWithDescribe<T>(argumentMatcher),
+                _                   => new GenericToNonGenericMatcherProxy<T>(argumentMatcher)
+            };
 
             return ref EnqueueArgSpecification<T>(new ArgumentSpecification(typeof(T), nonGenericMatcher));
         }
 
-        internal static ref T? Enqueue<T>(IArgumentMatcher argumentMatcher)
-        {
-            return ref EnqueueArgSpecification<T>(new ArgumentSpecification(typeof(T), argumentMatcher));
-        }
+        internal static ref T? Enqueue<T>(IArgumentMatcher argumentMatcher) =>
+            ref EnqueueArgSpecification<T>(new ArgumentSpecification(typeof(T), argumentMatcher));
 
-        internal static ref T? Enqueue<T>(IArgumentMatcher argumentMatcher, Action<object?> action)
-        {
-            return ref EnqueueArgSpecification<T>(new ArgumentSpecification(typeof(T), argumentMatcher, action));
-        }
+        internal static ref T? Enqueue<T>(IArgumentMatcher argumentMatcher, Action<object?> action) =>
+            ref EnqueueArgSpecification<T>(new ArgumentSpecification(typeof(T), argumentMatcher, action));
 
         private static ref T? EnqueueArgSpecification<T>(IArgumentSpecification specification)
         {
@@ -51,14 +44,14 @@ public GenericToNonGenericMatcherProxy(IArgumentMatcher<T> matcher)
                 _matcher = matcher;
             }
 
-            public bool IsSatisfiedBy(object? argument) => _matcher.IsSatisfiedBy((T) argument!);
+            public bool IsSatisfiedBy(object? argument) => _matcher.IsSatisfiedBy((T?) argument!);
         }
 
         private class GenericToNonGenericMatcherProxyWithDescribe<T> : GenericToNonGenericMatcherProxy<T>, IDescribeNonMatches
         {
             public GenericToNonGenericMatcherProxyWithDescribe(IArgumentMatcher<T> matcher) : base(matcher)
             {
-                if (matcher as IDescribeNonMatches == null) throw new ArgumentException("Should implement IDescribeNonMatches type.");
+                if (matcher is not IDescribeNonMatches) throw new SubstituteInternalException("Should implement IDescribeNonMatches type.");
             }
 
             public string DescribeFor(object? argument) => ((IDescribeNonMatches) _matcher).DescribeFor(argument);

src/NSubstitute/Core/Arguments/ArgumentSpecification.cs

@@ -4,8 +4,8 @@ namespace NSubstitute.Core.Arguments
 {
     public class ArgumentSpecification : IArgumentSpecification
     {
-        private static readonly Action<object?> NoOpAction = x => { };
- 
+        private static readonly Action<object?> NoOpAction = _ => { };
+
         private readonly IArgumentMatcher _matcher;
         private readonly Action<object?> _action;
         public Type ForType { get; }
@@ -22,26 +22,40 @@ public ArgumentSpecification(Type forType, IArgumentMatcher matcher, Action<obje
 
         public bool IsSatisfiedBy(object? argument)
         {
-            if (!IsCompatibleWith(argument)) return false;
-            try { return _matcher.IsSatisfiedBy(argument); }
-            catch { return false; }
+            if (!IsCompatibleWith(argument))
+            {
+                return false;
+            }
+
+            try
+            {
+                return _matcher.IsSatisfiedBy(argument);
+            }
+            catch
+            {
+                return false;
+            }
         }
 
         public string DescribeNonMatch(object? argument)
         {
-            var describable = _matcher as IDescribeNonMatches;
-            if (describable == null) return string.Empty;
+            if (!IsCompatibleWith(argument))
+            {
+                return GetIncompatibleTypeMessage(argument);
+            }
 
-            return IsCompatibleWith(argument) ? describable.DescribeFor(argument) : GetIncompatibleTypeMessage(argument);
+            return _matcher is IDescribeNonMatches describe
+                ? describe.DescribeFor(argument)
+                : string.Empty;
         }
 
         public string FormatArgument(object? argument)
         {
             var isSatisfiedByArg = IsSatisfiedBy(argument);
-            var matcherFormatter = _matcher as IArgumentFormatter;
-            return matcherFormatter == null
-                ? ArgumentFormatter.Default.Format(argument, !isSatisfiedByArg)
-                : matcherFormatter.Format(argument, isSatisfiedByArg);
+
+            return _matcher is IArgumentFormatter matcherFormatter
+                ? matcherFormatter.Format(argument, highlight: !isSatisfiedByArg)
+                : ArgumentFormatter.Default.Format(argument, highlight: !isSatisfiedByArg);
         }
 
         public override string ToString() => _matcher.ToString() ?? string.Empty;
@@ -63,19 +77,18 @@ public void RunAction(object? argument)
 
         private void RunActionIfTypeIsCompatible(object? argument)
         {
-            if (!argument.IsCompatibleWith(ForType)) return;
-            _action(argument);
+            if (argument.IsCompatibleWith(ForType))
+            {
+                _action(argument);
+            }
         }
 
-        private bool IsCompatibleWith(object? argument)
-        {
-            return argument.IsCompatibleWith(ForType);
-        }
+        private bool IsCompatibleWith(object? argument) => argument.IsCompatibleWith(ForType);
 
         private string GetIncompatibleTypeMessage(object? argument)
         {
             var argumentType = argument == null ? typeof(object) : argument.GetType();
-            return string.Format("Expected an argument compatible with type {0}. Actual type was {1}.", ForType, argumentType);
+            return $"Expected an argument compatible with type '{ForType}'. Actual type was '{argumentType}'.";
         }
     }
 }

src/NSubstitute/Core/Arguments/ArgumentSpecificationCompatibilityTester.cs

@@ -9,7 +9,7 @@ public class ArgumentSpecificationCompatibilityTester : IArgumentSpecificationCo
 
         public ArgumentSpecificationCompatibilityTester(IDefaultChecker defaultChecker)
         {
-            _defaultChecker = defaultChecker ?? throw new ArgumentNullException(nameof(defaultChecker));
+            _defaultChecker = defaultChecker;
         }
 
         public bool IsSpecificationCompatible(IArgumentSpecification specification, object? argumentValue, Type argumentType)

src/NSubstitute/Core/Arguments/ArrayContentsArgumentMatcher.cs

@@ -18,20 +18,18 @@ public bool IsSatisfiedBy(object? argument)
             if (argument != null)
             {
                 var argumentArray = ((IEnumerable) argument).Cast<object>().ToArray();
-                if (argumentArray.Length == _argumentSpecifications.Count())
+                if (argumentArray.Length == _argumentSpecifications.Length)
                 {
-                    return
-                        _argumentSpecifications.Select(
-                            (value, index) => value.IsSatisfiedBy(argumentArray[index])).All(x => x);
+                    return _argumentSpecifications
+                        .Select((spec, index) => spec.IsSatisfiedBy(argumentArray[index]))
+                        .All(x => x);
                 }
             }
+
             return false;
         }
 
-        public override string ToString()
-        {
-            return string.Join(", ", _argumentSpecifications.Select(x => x.ToString()));
-        }
+        public override string ToString() => string.Join(", ", _argumentSpecifications.Select(x => x.ToString()));
 
         public string Format(object? argument, bool highlight)
         {