Fix deprecation semantics to align with the GraphQL spec

src/HotChocolate/Core/src/Abstractions/GraphQLDeprecatedAttribute.cs

@@ -19,7 +19,7 @@ public sealed class GraphQLDeprecatedAttribute : Attribute
     /// <param name="deprecationReason">The deprecation reason.</param>
     public GraphQLDeprecatedAttribute(string deprecationReason)
     {
-        ArgumentException.ThrowIfNullOrEmpty(deprecationReason);
+        ArgumentException.ThrowIfNullOrWhiteSpace(deprecationReason);
 
         DeprecationReason = deprecationReason;
     }

src/HotChocolate/Core/src/Types.Abstractions/Serialization/SchemaDebugFormatter.cs

@@ -15,7 +15,7 @@ public static ObjectTypeDefinitionNode Format(IObjectTypeDefinition type)
                 DirectiveNames.Deprecated.Name,
                 new ArgumentNode(
                     DirectiveNames.Deprecated.Arguments.Reason,
-                    type.DeprecationReason ?? DirectiveNames.Deprecated.Arguments.DefaultReason));
+                    type.DeprecationReason));
 
             directives.Insert(0, deprecatedDirective);
         }
@@ -91,8 +91,7 @@ public static DirectiveDefinitionNode Format(IDirectiveDefinition directiveDefin
                 DirectiveNames.Deprecated.Name,
                 new ArgumentNode(
                     DirectiveNames.Deprecated.Arguments.Reason,
-                    directiveDefinition.DeprecationReason
-                        ?? DirectiveNames.Deprecated.Arguments.DefaultReason));
+                    directiveDefinition.DeprecationReason));
 
             directives.Insert(0, deprecatedDirective);
         }
@@ -119,7 +118,7 @@ public static FieldDefinitionNode Format(IOutputFieldDefinition field)
                 DirectiveNames.Deprecated.Name,
                 new ArgumentNode(
                     DirectiveNames.Deprecated.Arguments.Reason,
-                    field.DeprecationReason ?? DirectiveNames.Deprecated.Arguments.DefaultReason));
+                    field.DeprecationReason));
 
             directives.Insert(0, deprecatedDirective);
         }
@@ -145,7 +144,7 @@ public static InputValueDefinitionNode Format(IInputValueDefinition field)
                 DirectiveNames.Deprecated.Name,
                 new ArgumentNode(
                     DirectiveNames.Deprecated.Arguments.Reason,
-                    field.DeprecationReason ?? DirectiveNames.Deprecated.Arguments.DefaultReason));
+                    field.DeprecationReason));
 
             directives.Insert(0, deprecatedDirective);
         }
@@ -171,7 +170,7 @@ public static EnumValueDefinitionNode Format(IEnumValue value)
                 DirectiveNames.Deprecated.Name,
                 new ArgumentNode(
                     DirectiveNames.Deprecated.Arguments.Reason,
-                    value.DeprecationReason ?? DirectiveNames.Deprecated.Arguments.DefaultReason));
+                    value.DeprecationReason));
 
             directives.Insert(0, deprecatedDirective);
         }

src/HotChocolate/Core/src/Types.Abstractions/Serialization/SchemaFormatter.cs

@@ -631,17 +631,10 @@ private static List<DirectiveNode> ApplyDeprecatedDirective(
             return directives;
         }
 
-        private static DirectiveNode CreateDeprecatedDirective(string? reason = null)
-        {
-            if (string.IsNullOrEmpty(reason))
-            {
-                reason = DirectiveNames.Deprecated.Arguments.DefaultReason;
-            }
-
-            return new DirectiveNode(
+        private static DirectiveNode CreateDeprecatedDirective(string reason)
+            => new(
                 new NameNode(DirectiveNames.Deprecated.Name),
                 [new ArgumentNode(DirectiveNames.Deprecated.Arguments.Reason, reason)]);
-        }
 
         private static StringValueNode? CreateDescription(string? description)
         {

src/HotChocolate/Core/src/Types.Abstractions/Types/IDirectiveDefinition.cs

@@ -52,8 +52,6 @@ public interface IDirectiveDefinition
     IReadOnlyDirectiveCollection IDirectivesProvider.Directives
         => EmptyCollections.Directives;
 
-    bool IDeprecationProvider.IsDeprecated => false;
-
     string? IDeprecationProvider.DeprecationReason => null;
 
     /// <summary>

src/HotChocolate/Core/src/Types.Abstractions/Types/IObjectTypeDefinition.cs

@@ -25,7 +25,5 @@ public interface IObjectTypeDefinition
     , IDeprecationProvider
     , ISyntaxNodeProvider<ObjectTypeDefinitionNode>
 {
-    bool IDeprecationProvider.IsDeprecated => false;
-
     string? IDeprecationProvider.DeprecationReason => null;
 }

src/HotChocolate/Core/src/Types.Abstractions/Types/Provider/IDeprecationProvider.cs

@@ -1,3 +1,5 @@
+using System.Diagnostics.CodeAnalysis;
+
 #pragma warning disable IDE0130 // Namespace does not match folder structure
 // ReSharper disable once CheckNamespace
 namespace HotChocolate.Types;
@@ -10,12 +12,24 @@ public interface IDeprecationProvider : ITypeSystemMember
 {
     /// <summary>
     /// Defines if this <see cref="ITypeSystemMember"/> is deprecated.
+    /// This is <c>true</c> if a <see cref="DeprecationReason"/> is present.
+    /// </summary>
+    [MemberNotNullWhen(true, nameof(DeprecationReason))]
+    bool IsDeprecated => DeprecationReason is not null;
+
+    /// <summary>
+    /// Defines if this <see cref="ITypeSystemMember"/> is deprecated without
+    /// a specific deprecation reason being provided.
     /// </summary>
-    bool IsDeprecated { get; }
+    bool HasDefaultDeprecationReason
+        => string.Equals(
+            DeprecationReason,
+            DirectiveNames.Deprecated.Arguments.DefaultReason,
+            StringComparison.Ordinal);
 
     /// <summary>
     /// Gets the deprecation reason of this <see cref="ITypeSystemMember"/>,
-    /// or <c>null</c> if no reason was provided.
+    /// or <c>null</c> if this member is not deprecated.
     /// </summary>
     string? DeprecationReason { get; }
 }

src/HotChocolate/Core/src/Types/Types/Contracts/EnumValue.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics.CodeAnalysis;
 using HotChocolate.Configuration;
 using HotChocolate.Features;
 using HotChocolate.Language;
@@ -37,11 +38,14 @@ public abstract class EnumValue
 
     /// <summary>
     /// Defines if this enum value is deprecated.
+    /// This is <c>true</c> if a <see cref="DeprecationReason"/> is present.
     /// </summary>
-    public abstract bool IsDeprecated { get; }
+    [MemberNotNullWhen(true, nameof(DeprecationReason))]
+    public bool IsDeprecated => DeprecationReason is not null;
 
     /// <summary>
-    /// Gets the deprecation reason for this enum value.
+    /// Gets the deprecation reason for this enum value,
+    /// or <c>null</c> if this enum value is not deprecated.
     /// </summary>
     public abstract string? DeprecationReason { get; }
 

src/HotChocolate/Core/src/Types/Types/DefaultEnumValue.cs

@@ -27,8 +27,9 @@ public DefaultEnumValue(EnumValueConfiguration configuration)
             ? configuration.RuntimeValue.ToString()!
             : configuration.Name;
         Description = configuration.Description;
-        DeprecationReason = configuration.DeprecationReason;
-        IsDeprecated = !string.IsNullOrEmpty(configuration.DeprecationReason);
+        DeprecationReason = string.IsNullOrWhiteSpace(configuration.DeprecationReason)
+            ? null
+            : configuration.DeprecationReason;
         Value = configuration.RuntimeValue;
         Features = configuration.GetFeatures();
     }
@@ -37,8 +38,6 @@ public DefaultEnumValue(EnumValueConfiguration configuration)
 
     public override string? Description { get; }
 
-    public override bool IsDeprecated { get; }
-
     public override string? DeprecationReason { get; }
 
     public override object Value { get; }

src/HotChocolate/Core/src/Types/Types/Descriptors/ArgumentDescriptorBase~1.cs

@@ -27,7 +27,7 @@ protected ArgumentDescriptorBase(IDescriptorContext context)
     /// <inheritdoc cref="IArgumentDescriptor.Deprecated(string)"/>
     protected void Deprecated(string? reason)
     {
-        if (string.IsNullOrEmpty(reason))
+        if (string.IsNullOrWhiteSpace(reason))
         {
             Deprecated();
         }

src/HotChocolate/Core/src/Types/Types/Descriptors/Configurations/DirectiveTypeConfiguration.cs

@@ -57,7 +57,7 @@ public DirectiveTypeConfiguration(
     /// <summary>
     /// Defines if this directive is deprecated.
     /// </summary>
-    public bool IsDeprecated => !string.IsNullOrEmpty(DeprecationReason);
+    public bool IsDeprecated => !string.IsNullOrWhiteSpace(DeprecationReason);
 
     /// <summary>
     /// Gets the list of directives that are annotated to this directive.

src/HotChocolate/Core/src/Types/Types/Descriptors/Configurations/EnumValueConfiguration.cs

@@ -37,7 +37,7 @@ public EnumValueConfiguration(
     /// <summary>
     /// Defines if this enum value is deprecated.
     /// </summary>
-    public bool IsDeprecated => !string.IsNullOrEmpty(DeprecationReason);
+    public bool IsDeprecated => !string.IsNullOrWhiteSpace(DeprecationReason);
 
     /// <summary>
     /// Defines if this enum value is ignored

src/HotChocolate/Core/src/Types/Types/Descriptors/Configurations/FieldConfiguration.cs

@@ -29,7 +29,7 @@ public string? DeprecationReason
         get => _deprecationReason;
         set
         {
-            if (string.IsNullOrEmpty(value))
+            if (string.IsNullOrWhiteSpace(value))
             {
                 Flags &= ~CoreFieldFlags.Deprecated;
             }

src/HotChocolate/Core/src/Types/Types/Descriptors/DirectiveTypeDescriptor.cs

@@ -106,7 +106,7 @@ public IDirectiveTypeDescriptor Description(string value)
 
     public IDirectiveTypeDescriptor Deprecated(string? reason)
     {
-        if (string.IsNullOrEmpty(reason))
+        if (string.IsNullOrWhiteSpace(reason))
         {
             return Deprecated();
         }

src/HotChocolate/Core/src/Types/Types/Descriptors/EnumValueDescriptor.cs

@@ -77,7 +77,7 @@ public IEnumValueDescriptor Description(string value)
 
     public IEnumValueDescriptor Deprecated(string reason)
     {
-        if (string.IsNullOrEmpty(reason))
+        if (string.IsNullOrWhiteSpace(reason))
         {
             return Deprecated();
         }

src/HotChocolate/Core/src/Types/Types/Descriptors/ObjectTypeDescriptor.cs

@@ -265,7 +265,7 @@ public IObjectTypeDescriptor Deprecated(string? reason)
             throw ThrowHelper.ObjectDeprecationNotEnabled(Configuration.Name);
         }
 
-        Configuration.DeprecationReason = string.IsNullOrEmpty(reason)
+        Configuration.DeprecationReason = string.IsNullOrWhiteSpace(reason)
             ? DirectiveNames.Deprecated.Arguments.DefaultReason
             : reason;
 

src/HotChocolate/Core/src/Types/Types/Descriptors/OutputFieldDescriptorBase.cs

@@ -123,7 +123,7 @@ protected void Argument(
 
     public void Deprecated(string? reason)
     {
-        if (string.IsNullOrEmpty(reason))
+        if (string.IsNullOrWhiteSpace(reason))
         {
             Deprecated();
         }

src/HotChocolate/Core/src/Types/Types/DirectiveType.Initialization.cs

@@ -67,8 +67,9 @@ protected override void OnCompleteType(
         _inputParser = context.DescriptorContext.InputParser;
 
         Locations = configuration.Locations;
-        IsDeprecated = !string.IsNullOrEmpty(configuration.DeprecationReason);
-        DeprecationReason = configuration.DeprecationReason;
+        DeprecationReason = string.IsNullOrWhiteSpace(configuration.DeprecationReason)
+            ? null
+            : configuration.DeprecationReason;
         Arguments = OnCompleteFields(context, configuration);
         IsPublic = configuration.IsPublic
             || context.DescriptorContext.Options.DisableInternalDirectives;

src/HotChocolate/Core/src/Types/Types/DirectiveType.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics.CodeAnalysis;
 using HotChocolate.Language;
 using HotChocolate.Resolvers;
 using HotChocolate.Types.Descriptors.Configurations;
@@ -91,11 +92,14 @@ IReadOnlyDirectiveCollection IDirectivesProvider.Directives
 
     /// <summary>
     /// Defines if this directive is deprecated.
+    /// This is <c>true</c> if a <see cref="DeprecationReason"/> is present.
     /// </summary>
-    public bool IsDeprecated { get; private set; }
+    [MemberNotNullWhen(true, nameof(DeprecationReason))]
+    public bool IsDeprecated => DeprecationReason is not null;
 
     /// <summary>
-    /// Gets the deprecation reason of this directive.
+    /// Gets the deprecation reason of this directive,
+    /// or <c>null</c> if this directive is not deprecated.
     /// </summary>
     public string? DeprecationReason { get; private set; }
 

src/HotChocolate/Core/src/Types/Types/Factories/SdlToTypeSystemHelper.cs

@@ -44,7 +44,7 @@ public static void AddDirectives<TOwner>(
         if (directive.Arguments.Count != 0
             && directive.Arguments[0].Name.Value == DirectiveNames.Deprecated.Arguments.Reason
             && directive.Arguments[0].Value is StringValueNode s
-            && !string.IsNullOrEmpty(s.Value))
+            && !string.IsNullOrWhiteSpace(s.Value))
         {
             return s.Value;
         }
@@ -57,7 +57,7 @@ public static string DeprecationReason(this DirectiveNode directive)
         if (directive.Arguments.Count != 0
             && directive.Arguments[0].Name.Value == DirectiveNames.Deprecated.Arguments.Reason
             && directive.Arguments[0].Value is StringValueNode s
-            && !string.IsNullOrEmpty(s.Value))
+            && !string.IsNullOrWhiteSpace(s.Value))
         {
             return s.Value;
         }

src/HotChocolate/Core/src/Types/Types/FieldBase.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics.CodeAnalysis;
 using HotChocolate.Configuration;
 using HotChocolate.Features;
 using HotChocolate.Language;
@@ -37,8 +38,9 @@ protected FieldBase(FieldConfiguration configuration, int index)
 
         Name = configuration.Name.EnsureGraphQLName();
         Description = configuration.Description;
-        IsDeprecated = !string.IsNullOrEmpty(configuration.DeprecationReason);
-        DeprecationReason = configuration.DeprecationReason;
+        DeprecationReason = string.IsNullOrWhiteSpace(configuration.DeprecationReason)
+            ? null
+            : configuration.DeprecationReason;
         Flags = configuration.Flags;
         DeclaringType = null!;
         DeclaringMember = null!;
@@ -66,7 +68,6 @@ protected FieldBase(FieldBase original, IType type)
         Index = original.Index;
         Name = original.Name;
         Description = original.Description;
-        IsDeprecated = original.IsDeprecated;
         DeprecationReason = original.DeprecationReason;
         DeclaringType = original.DeclaringType;
         DeclaringMember = original.DeclaringMember;
@@ -106,7 +107,8 @@ IReadOnlyDirectiveCollection IDirectivesProvider.Directives
         => Directives.AsReadOnlyDirectiveCollection();
 
     /// <inheritdoc />
-    public bool IsDeprecated { get; }
+    [MemberNotNullWhen(true, nameof(DeprecationReason))]
+    public bool IsDeprecated => DeprecationReason is not null;
 
     /// <inheritdoc />
     public string? DeprecationReason { get; }

src/HotChocolate/Core/src/Types/Types/ObjectType.Initialization.cs

@@ -61,8 +61,9 @@ protected override void OnCompleteType(
     {
         base.OnCompleteType(context, configuration);
 
-        IsDeprecated = !string.IsNullOrEmpty(configuration.DeprecationReason);
-        DeprecationReason = configuration.DeprecationReason;
+        DeprecationReason = string.IsNullOrWhiteSpace(configuration.DeprecationReason)
+            ? null
+            : configuration.DeprecationReason;
 
         if (ValidateFields(context, configuration))
         {

src/HotChocolate/Core/src/Types/Types/ObjectType.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics.CodeAnalysis;
 using HotChocolate.Language;
 using HotChocolate.Resolvers;
 using HotChocolate.Types.Descriptors.Configurations;
@@ -83,7 +84,8 @@ IReadOnlyFieldDefinitionCollection<IOutputFieldDefinition> IComplexTypeDefinitio
         => Fields.AsReadOnlyFieldDefinitionCollection();
 
     /// <inheritdoc />
-    public bool IsDeprecated { get; private set; }
+    [MemberNotNullWhen(true, nameof(DeprecationReason))]
+    public bool IsDeprecated => DeprecationReason is not null;
 
     /// <inheritdoc />
     public string? DeprecationReason { get; private set; }

src/HotChocolate/Core/test/Types.Abstractions.Tests/Serialization/SchemaDebugFormatterTests.cs

@@ -36,31 +36,4 @@ type Foo implements Bar @deprecated(reason: "Use Bar.") @example {
             }
             """);
     }
-
-    [Fact]
-    public void Format_Should_UseDefaultReason_When_ObjectTypeHasNoDeprecationReason()
-    {
-        // arrange
-        // the deprecation state is set programmatically, so the formatter synthesizes @deprecated
-        const string sdl =
-            """
-            type Foo {
-              id: ID
-            }
-            """;
-        var schema = SchemaParser.Parse(Encoding.UTF8.GetBytes(sdl));
-        var fooType = (MutableObjectTypeDefinition)schema.Types["Foo"];
-        fooType.IsDeprecated = true;
-
-        // act
-        var syntaxNode = SchemaDebugFormatter.Format(fooType);
-
-        // assert
-        syntaxNode.ToString().MatchInlineSnapshot(
-            """
-            type Foo @deprecated(reason: "No longer supported.") {
-              id: ID
-            }
-            """);
-    }
 }

src/HotChocolate/Core/test/Types.Tests/Types/Descriptors/ObjectTypeDescriptorTests.cs

@@ -250,6 +250,7 @@ public void Deprecated_NoReason_SetsDefaultReason()
     [Theory]
     [InlineData(null)]
     [InlineData("")]
+    [InlineData("   ")]
     public void Deprecated_EmptyReason_SetsDefaultReason(string? reason)
     {
         // arrange