Add some exception messages (#389)

* Add some exception messages

* Code style changes

src/neo-vm/EvaluationStack.cs

@@ -50,7 +50,7 @@ IEnumerator IEnumerable.GetEnumerator()
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         internal void Insert(int index, StackItem item)
         {
-            if (index > innerList.Count) throw new InvalidOperationException();
+            if (index > innerList.Count) throw new InvalidOperationException($"Insert out of bounds: {index}/{innerList.Count}");
             innerList.Insert(innerList.Count - index, item);
             referenceCounter.AddStackReference(item);
         }
@@ -68,11 +68,11 @@ internal void MoveTo(EvaluationStack stack, int count = -1)
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public StackItem Peek(int index = 0)
         {
-            if (index >= innerList.Count) throw new InvalidOperationException();
+            if (index >= innerList.Count) throw new InvalidOperationException($"Peek out of bounds: {index}/{innerList.Count}");
             if (index < 0)
             {
                 index += innerList.Count;
-                if (index < 0) throw new InvalidOperationException();
+                if (index < 0) throw new InvalidOperationException($"Peek out of bounds: {index}/{innerList.Count}");
             }
             return innerList[innerList.Count - index - 1];
         }
@@ -118,7 +118,7 @@ internal T Remove<T>(int index) where T : StackItem
                     throw new ArgumentOutOfRangeException(nameof(index));
             }
             index = innerList.Count - index - 1;
-            if (!(innerList[index] is T item))
+            if (innerList[index] is not T item)
                 throw new InvalidCastException($"The item can't be casted to type {typeof(T)}");
             innerList.RemoveAt(index);
             referenceCounter.RemoveStackReference(item);

src/neo-vm/ExecutionEngine.cs

@@ -368,7 +368,7 @@ private void ExecuteInstruction()
                         if (context_pop.EvaluationStack != stack_eval)
                         {
                             if (context_pop.RVCount >= 0 && context_pop.EvaluationStack.Count != context_pop.RVCount)
-                                throw new InvalidOperationException();
+                                throw new InvalidOperationException("RVCount doesn't match with EvaluationStack");
                             context_pop.EvaluationStack.CopyTo(stack_eval);
                         }
                         if (InvocationStack.Count == 0)
@@ -1046,19 +1046,13 @@ private void ExecuteInstruction()
                     }
                 case OpCode.VALUES:
                     {
-                        IEnumerable<StackItem> values;
                         var x = Pop();
-                        switch (x)
+                        IEnumerable<StackItem> values = x switch
                         {
-                            case VMArray array:
-                                values = array;
-                                break;
-                            case Map map:
-                                values = map.Values;
-                                break;
-                            default:
-                                throw new InvalidOperationException($"Invalid type for {instruction.OpCode}: {x.Type}");
-                        }
+                            VMArray array => array,
+                            Map map => map.Values,
+                            _ => throw new InvalidOperationException($"Invalid type for {instruction.OpCode}: {x.Type}"),
+                        };
                         VMArray newArray = new VMArray(ReferenceCounter);
                         foreach (StackItem item in values)
                             if (item is Struct s)
@@ -1145,7 +1139,7 @@ private void ExecuteInstruction()
                                     int index = key.ToInt32();
                                     if (index < 0 || index >= buffer.Size)
                                         throw new InvalidOperationException($"The value {index} is out of range.");
-                                    if (!(value is PrimitiveType p))
+                                    if (value is not PrimitiveType p)
                                         throw new InvalidOperationException($"Value must be a primitive type in {instruction.OpCode}");
                                     int b = p.ToInt32();
                                     if (b < sbyte.MinValue || b > byte.MaxValue)
@@ -1381,7 +1375,7 @@ private void HandleException()
         protected virtual void LoadContext(ExecutionContext context)
         {
             if (InvocationStack.Count >= Limits.MaxInvocationStackSize)
-                throw new InvalidOperationException();
+                throw new InvalidOperationException($"MaxInvocationStackSize exceed: {InvocationStack.Count}");
             InvocationStack.Push(context);
             if (EntryContext is null) EntryContext = context;
             CurrentContext = context;

src/neo-vm/Instruction.cs

@@ -161,7 +161,7 @@ internal Instruction(byte[] script, int ip)
             {
                 ip += operandSizePrefix;
                 if (ip + operandSize > script.Length)
-                    throw new InvalidOperationException();
+                    throw new InvalidOperationException($"Instrucion out of bounds. InstructionPointer: {ip}, operandSize: {operandSize}, length: {script.Length}");
                 Operand = new ReadOnlyMemory<byte>(script, ip, operandSize);
             }
         }

src/neo-vm/ReferenceCounter.cs

@@ -21,7 +21,7 @@ private class Entry
         internal void AddReference(StackItem referred, CompoundType parent)
         {
             references_count++;
-            if (!(referred is CompoundType compound)) return;
+            if (referred is not CompoundType compound) return;
             if (!counter.TryGetValue(compound, out Entry tracing))
             {
                 tracing = new Entry();
@@ -46,7 +46,7 @@ internal void AddReference(StackItem referred, CompoundType parent)
         internal void AddStackReference(StackItem referred)
         {
             references_count++;
-            if (!(referred is CompoundType compound)) return;
+            if (referred is not CompoundType compound) return;
             if (counter.TryGetValue(compound, out Entry entry))
                 entry.StackReferences++;
             else
@@ -108,7 +108,7 @@ internal int CheckZeroReferred()
         internal void RemoveReference(StackItem referred, CompoundType parent)
         {
             references_count--;
-            if (!(referred is CompoundType compound)) return;
+            if (referred is not CompoundType compound) return;
             Entry entry = counter[compound];
             entry.ObjectReferences[parent] -= 1;
             if (entry.StackReferences == 0)
@@ -118,7 +118,7 @@ internal void RemoveReference(StackItem referred, CompoundType parent)
         internal void RemoveStackReference(StackItem referred)
         {
             references_count--;
-            if (!(referred is CompoundType item_compound)) return;
+            if (referred is not CompoundType item_compound) return;
             if (--counter[item_compound].StackReferences == 0)
                 zero_referred.Add(item_compound);
         }

src/neo-vm/Types/ByteString.cs

@@ -25,7 +25,7 @@ public override bool Equals(StackItem other)
             if (Size > MaxComparableSize)
                 throw new InvalidOperationException("The operand exceeds the maximum comparable size.");
             if (ReferenceEquals(this, other)) return true;
-            if (!(other is ByteString b)) return false;
+            if (other is not ByteString b) return false;
             if (b.Size > MaxComparableSize)
                 throw new InvalidOperationException("The operand exceeds the maximum comparable size.");
             return GetSpan().SequenceEqual(b.GetSpan());
@@ -50,7 +50,7 @@ public override int GetHashCode()
 
         public override BigInteger GetInteger()
         {
-            if (Size > Integer.MaxSize) throw new InvalidCastException();
+            if (Size > Integer.MaxSize) throw new InvalidCastException($"MaxSize exceed: {Size}");
             return new BigInteger(GetSpan());
         }
 

src/neo-vm/Types/Integer.cs

@@ -26,7 +26,7 @@ public Integer(BigInteger value)
             else
             {
                 Size = value.GetByteCount();
-                if (Size > MaxSize) throw new ArgumentException();
+                if (Size > MaxSize) throw new ArgumentException($"MaxSize exceed: {Size}");
             }
             this.value = value;
         }

src/neo-vm/Types/InteropInterface.cs

@@ -12,7 +12,7 @@ public class InteropInterface : StackItem
 
         public InteropInterface(object value)
         {
-            _object = value ?? throw new ArgumentException();
+            _object = value ?? throw new ArgumentNullException(nameof(value));
         }
 
         public override bool Equals(StackItem other)
@@ -35,7 +35,7 @@ public override int GetHashCode()
         public override T GetInterface<T>()
         {
             if (_object is T t) return t;
-            throw new InvalidCastException();
+            throw new InvalidCastException($"The item can't be casted to type {typeof(T)}");
         }
     }
 }

src/neo-vm/Types/Map.cs

@@ -21,7 +21,7 @@ public StackItem this[PrimitiveType key]
             set
             {
                 if (key.Size > MaxKeySize)
-                    throw new ArgumentException();
+                    throw new ArgumentException($"MaxKeySize exceed: {key.Size}");
                 if (ReferenceCounter != null)
                 {
                     if (dictionary.TryGetValue(key, out StackItem old_value))

src/neo-vm/Types/Null.cs

@@ -11,7 +11,7 @@ internal Null() { }
         public override StackItem ConvertTo(StackItemType type)
         {
             if (type == StackItemType.Any || !Enum.IsDefined(typeof(StackItemType), type))
-                throw new InvalidCastException();
+                throw new InvalidCastException($"Type can't be converted to StackItemType: {type}");
             return this;
         }
 

src/neo-vm/Types/PrimitiveType.cs

@@ -39,7 +39,7 @@ public sealed override ReadOnlySpan<byte> GetSpan()
         public int ToInt32()
         {
             BigInteger i = GetInteger();
-            if (i < int.MinValue || i > int.MaxValue) throw new InvalidCastException();
+            if (i < int.MinValue || i > int.MaxValue) throw new InvalidCastException($"{i} can't be converted to a valid integer value");
             return (int)i;
         }
 

src/neo-vm/Types/Struct.cs

@@ -53,7 +53,7 @@ public override StackItem ConvertTo(StackItemType type)
 
         public override bool Equals(StackItem other)
         {
-            if (!(other is Struct s)) return false;
+            if (other is not Struct s) return false;
             Stack<StackItem> stack1 = new Stack<StackItem>();
             Stack<StackItem> stack2 = new Stack<StackItem>();
             stack1.Push(this);
@@ -65,7 +65,7 @@ public override bool Equals(StackItem other)
                 if (a is Struct sa)
                 {
                     if (ReferenceEquals(a, b)) continue;
-                    if (!(b is Struct sb)) return false;
+                    if (b is not Struct sb) return false;
                     if (sa.Count != sb.Count) return false;
                     foreach (StackItem item in sa)
                         stack1.Push(item);

tests/neo-vm.Tests/UtStackItem.cs

@@ -59,7 +59,7 @@ public void HashCodeTest()
 
             Assert.IsTrue(itemA.GetHashCode() == itemB.GetHashCode());
 
-            var script = new Script(new byte[0]);
+            var script = new Script(System.Array.Empty<byte>());
             itemA = new Pointer(script, 123);
             itemB = new Pointer(script, 123);
             itemC = new Pointer(script, 1234);
@@ -71,7 +71,7 @@ public void HashCodeTest()
         [TestMethod]
         public void NullTest()
         {
-            StackItem nullItem = new byte[0];
+            StackItem nullItem = System.Array.Empty<byte>();
             Assert.AreNotEqual(StackItem.Null, nullItem);
 
             nullItem = new Null();

tests/neo-vm.Tests/UtStruct.cs

@@ -28,9 +28,7 @@ public void Clone()
         }
 
         [TestMethod]
-#pragma warning disable xUnit1024 // Test methods cannot have overloads
         public void Equals()
-#pragma warning restore xUnit1024 // Test methods cannot have overloads
         {
             Struct s1 = new Struct { 1, new Struct { 2 } };
             Struct s2 = new Struct { 1, new Struct { 2 } };

tests/neo-vm.Tests/UtUnsafe.cs

@@ -9,7 +9,7 @@ public class UtUnsafe
         [TestMethod]
         public void NotZero()
         {
-            Assert.IsFalse(Unsafe.NotZero(new byte[0]));
+            Assert.IsFalse(Unsafe.NotZero(System.Array.Empty<byte>()));
             Assert.IsFalse(Unsafe.NotZero(new byte[4]));
             Assert.IsFalse(Unsafe.NotZero(new byte[8]));
             Assert.IsFalse(Unsafe.NotZero(new byte[11]));