Transfer ownership in ReflectionMetadataHook.Register instead of cloning

src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/CompositeSourceGeneratedReflectionDataProvider.cs

@@ -222,7 +222,7 @@ private static SourceGeneratedReflectionDataProvider BuildMergedSnapshot(IReadOn
  };
  }
 
- private static void MergeInto<TKey, TValue>(Dictionary<TKey, TValue> target, Dictionary<TKey, TValue> source)
+ private static void MergeInto<TKey, TValue>(Dictionary<TKey, TValue> target, IReadOnlyDictionary<TKey, TValue> source)
  where TKey : notnull
  {
  foreach (KeyValuePair<TKey, TValue> kvp in source)

src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/ReflectionMetadataHook.cs

@@ -52,8 +52,8 @@ public static class ReflectionMetadataHook
  /// <param name="types">All types directly annotated with <c>[TestClass]</c> in the assembly.</param>
  /// <param name="testMethods">
  /// A map from each test class to its <c>[TestMethod]</c>-annotated <see cref="MethodInfo"/>
- /// set. The dictionary and arrays are copied defensively; the caller may mutate the inputs
- /// after the call.
+ /// set. Ownership transfers to the adapter: the source generator hands over freshly-built
+ /// collections and must not mutate them after the call (see the remarks on the full overload).
  /// </param>
  /// <remarks>
  /// Do not call this method from hand-written code; it is meant to be invoked exclusively from
@@ -120,8 +120,21 @@ public static void Register(
  /// assigns it directly.
  /// </param>
  /// <remarks>
+ /// <para>
  /// Do not call this method from hand-written code; it is meant to be invoked exclusively from
  /// the <c>[ModuleInitializer]</c> emitted by the MSTest source generator.
+ /// </para>
+ /// <para>
+ /// <b>Ownership transfer.</b> The adapter takes ownership of every collection passed in
+ /// (the <paramref name="types"/> array, the <paramref name="assemblyAttributes"/> array, and
+ /// each dictionary with its value arrays) and stores them without cloning; the read-only
+ /// dictionaries are held as-is behind <see cref="IReadOnlyDictionary{TKey, TValue}"/>. Callers
+ /// MUST hand over freshly-built collections and MUST NOT mutate them after the call returns;
+ /// the source generator (the only intended caller) already emits fresh, throwaway collections
+ /// that satisfy this. This is a contract about ownership and mutation, not caller identity: it
+ /// trades the previous defensive copies for zero-copy startup on the understanding that the
+ /// inputs are the adapter's to keep.
+ /// </para>
  /// </remarks>
  [EditorBrowsable(EditorBrowsableState.Never)]
  public static void Register(
@@ -174,29 +187,14 @@ public static void Register(
  throw new ArgumentNullException(nameof(propertySetters));
  }
 
- var typesCopy = (Type[])types.Clone();
-
- var testMethodsCopy = new Dictionary<Type, MethodInfo[]>(testMethods.Count);
- foreach (KeyValuePair<Type, MethodInfo[]> kvp in testMethods)
- {
- testMethodsCopy[kvp.Key] = (MethodInfo[])kvp.Value.Clone();
- }
-
- var typeAttributesCopy = new Dictionary<Type, Attribute[]>(typeAttributes.Count);
- foreach (KeyValuePair<Type, Attribute[]> kvp in typeAttributes)
- {
- typeAttributesCopy[kvp.Key] = (Attribute[])kvp.Value.Clone();
- }
-
- object[] assemblyAttributesCopy = (object[])assemblyAttributes.Clone();
-
- var methodInvokersCopy = new Dictionary<MethodInfo, Func<object?, object?[]?, object?>>(methodInvokers.Count);
- foreach (KeyValuePair<MethodInfo, Func<object?, object?[]?, object?>> kvp in methodInvokers)
- {
- methodInvokersCopy[kvp.Key] = kvp.Value;
- }
-
- var constructorInvokersCopy = new Dictionary<Type, SourceGeneratedReflectionDataProvider.ConstructorInvoker[]>(constructorInvokers.Count);
+ // Ownership transfer (see the remarks on this method): the source generator hands over
+ // freshly-built, throwaway collections and never mutates them after the call, so we store
+ // the passed arrays and read-only dictionaries directly instead of copying them.
+ //
+ // ConstructorInvokerInfo (public struct) still has to be projected onto the adapter's
+ // internal ConstructorInvoker type; this is a representation change, not a defensive copy,
+ // and the parameter-type arrays are taken by reference.
+ var constructorInvokersMap = new Dictionary<Type, SourceGeneratedReflectionDataProvider.ConstructorInvoker[]>(constructorInvokers.Count);
  foreach (KeyValuePair<Type, ConstructorInvokerInfo[]> kvp in constructorInvokers)
  {
  var invokers = new SourceGeneratedReflectionDataProvider.ConstructorInvoker[kvp.Value.Length];
@@ -205,26 +203,20 @@ public static void Register(
  ConstructorInvokerInfo info = kvp.Value[i];
  invokers[i] = new SourceGeneratedReflectionDataProvider.ConstructorInvoker
  {
- Parameters = (Type[])info.ParameterTypes.Clone(),
+ Parameters = info.ParameterTypes,
  Invoker = info.Invoker,
  };
  }
 
- constructorInvokersCopy[kvp.Key] = invokers;
- }
-
- var propertySettersCopy = new Dictionary<PropertyInfo, Action<object?, object?>>(propertySetters.Count);
- foreach (KeyValuePair<PropertyInfo, Action<object?, object?>> kvp in propertySetters)
- {
- propertySettersCopy[kvp.Key] = kvp.Value;
+ constructorInvokersMap[kvp.Key] = invokers;
  }
 
  // TypesByName must always match Type.FullName at runtime (see comment in the source
  // generator emitter): compute it on the runtime side from typeof(T).FullName so the
  // generator emits less code and the same FullName conventions are honored for nested
  // and generic types.
- var typesByName = new Dictionary<string, Type>(typesCopy.Length, StringComparer.Ordinal);
- foreach (Type type in typesCopy)
+ var typesByName = new Dictionary<string, Type>(types.Length, StringComparer.Ordinal);
+ foreach (Type type in types)
  {
  if (type.FullName is { } fullName)
  {
@@ -236,14 +228,14 @@ public static void Register(
  {
  Assembly = assembly,
  AssemblyName = assembly.GetName().Name ?? string.Empty,
- Types = typesCopy,
+ Types = types,
  TypesByName = typesByName,
- TypeMethods = testMethodsCopy,
- TypeAttributes = typeAttributesCopy,
- AssemblyAttributes = assemblyAttributesCopy,
- TypeMethodInvokers = methodInvokersCopy,
- TypeConstructorsInvoker = constructorInvokersCopy,
- TypePropertySetters = propertySettersCopy,
+ TypeMethods = testMethods,
+ TypeAttributes = typeAttributes,
+ AssemblyAttributes = assemblyAttributes,
+ TypeMethodInvokers = methodInvokers,
+ TypeConstructorsInvoker = constructorInvokersMap,
+ TypePropertySetters = propertySetters,
  };
 
  lock (Lock)

src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionDataProvider.cs

@@ -33,13 +33,13 @@ internal class SourceGeneratedReflectionDataProvider
  /// <summary>
  /// Gets a lookup of types by full name.
  /// </summary>
- public Dictionary<string, Type> TypesByName { get; init; } = [];
+ public IReadOnlyDictionary<string, Type> TypesByName { get; init; } = new Dictionary<string, Type>();
 
  /// <summary>
  /// Gets attributes declared on each type. The array contains attribute instances
  /// already inflated by the source generator so no reflection call is required to read them.
  /// </summary>
- public Dictionary<Type, Attribute[]> TypeAttributes { get; init; } = [];
+ public IReadOnlyDictionary<Type, Attribute[]> TypeAttributes { get; init; } = new Dictionary<Type, Attribute[]>();
 
  /// <summary>
  /// Gets attribute instances declared at the assembly level.
@@ -50,7 +50,7 @@ internal class SourceGeneratedReflectionDataProvider
  /// Gets the properties declared on each type that MSTest may inspect (for example
  /// <c>TestContext</c> properties or properties referenced by <c>DynamicData</c>).
  /// </summary>
- public Dictionary<Type, PropertyInfo[]> TypeProperties { get; init; } = [];
+ public IReadOnlyDictionary<Type, PropertyInfo[]> TypeProperties { get; init; } = new Dictionary<Type, PropertyInfo[]>();
 
  /// <summary>
  /// Gets the methods declared on each type that the source generator was able to surface
@@ -62,36 +62,36 @@ internal class SourceGeneratedReflectionDataProvider
  /// source for <c>BindingFlags.DeclaredOnly</c>-style enumerations; the reflection-backed
  /// fallback is responsible for completeness.
  /// </remarks>
- public Dictionary<Type, MethodInfo[]> TypeMethods { get; init; } = [];
+ public IReadOnlyDictionary<Type, MethodInfo[]> TypeMethods { get; init; } = new Dictionary<Type, MethodInfo[]>();
 
  /// <summary>
  /// Gets source-location data for each type's methods so navigation in the IDE works
  /// without a PDB round-trip.
  /// </summary>
- public Dictionary<string, TypeLocation> TypeMethodLocations { get; init; } = [];
+ public IReadOnlyDictionary<string, TypeLocation> TypeMethodLocations { get; init; } = new Dictionary<string, TypeLocation>();
 
  /// <summary>
  /// Gets attributes declared on each method, keyed by the <see cref="MethodInfo"/> instance
  /// that the source-generator resolved at startup. Keying by <see cref="MethodInfo"/>
  /// (rather than method name) preserves the ability to distinguish overloaded methods.
  /// </summary>
- public Dictionary<MethodInfo, Attribute[]> TypeMethodAttributes { get; init; } = [];
+ public IReadOnlyDictionary<MethodInfo, Attribute[]> TypeMethodAttributes { get; init; } = new Dictionary<MethodInfo, Attribute[]>();
 
  /// <summary>
  /// Gets constructors declared on each type. These are returned by
  /// <c>GetDeclaredConstructors</c>.
  /// </summary>
- public Dictionary<Type, ConstructorInfo[]> TypeConstructors { get; init; } = [];
+ public IReadOnlyDictionary<Type, ConstructorInfo[]> TypeConstructors { get; init; } = new Dictionary<Type, ConstructorInfo[]>();
 
  /// <summary>
  /// Gets a lookup of properties on a type by property name.
  /// </summary>
- public Dictionary<Type, Dictionary<string, PropertyInfo>> TypePropertiesByName { get; init; } = [];
+ public IReadOnlyDictionary<Type, Dictionary<string, PropertyInfo>> TypePropertiesByName { get; init; } = new Dictionary<Type, Dictionary<string, PropertyInfo>>();
 
  /// <summary>
  /// Gets the constructor invokers that allow instantiating types without reflection.
  /// </summary>
- public Dictionary<Type, ConstructorInvoker[]> TypeConstructorsInvoker { get; init; } = [];
+ public IReadOnlyDictionary<Type, ConstructorInvoker[]> TypeConstructorsInvoker { get; init; } = new Dictionary<Type, ConstructorInvoker[]>();
 
  /// <summary>
  /// Gets the delegate-based invokers for test methods and fixtures, keyed by the
@@ -102,14 +102,14 @@ internal class SourceGeneratedReflectionDataProvider
  /// a <see cref="System.Threading.Tasks.ValueTask"/> is converted with <c>AsTask()</c>, and any
  /// return value is discarded — so callers can simply await the result.
  /// </summary>
- public Dictionary<MethodInfo, Func<object?, object?[]?, object?>> TypeMethodInvokers { get; init; } = [];
+ public IReadOnlyDictionary<MethodInfo, Func<object?, object?[]?, object?>> TypeMethodInvokers { get; init; } = new Dictionary<MethodInfo, Func<object?, object?[]?, object?>>();
 
  /// <summary>
  /// Gets the delegate-based property setters, keyed by the <see cref="PropertyInfo"/> the
  /// adapter holds (today: the <c>TestContext</c> property). Each delegate assigns the value
  /// directly instead of calling <see cref="PropertyInfo.SetValue(object, object)"/>.
  /// </summary>
- public Dictionary<PropertyInfo, Action<object?, object?>> TypePropertySetters { get; init; } = [];
+ public IReadOnlyDictionary<PropertyInfo, Action<object?, object?>> TypePropertySetters { get; init; } = new Dictionary<PropertyInfo, Action<object?, object?>>();
 
  /// <summary>
  /// Returns the snapshot of merged metadata that callers should read. Single-assembly

test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/SourceGeneration/SourceGeneratedReflectionOperationsTests.cs

@@ -34,7 +34,7 @@ public void GetTestMethodInvoker_ReturnsRegisteredDelegate_AndInvokesWithoutRefl
 
  var provider = new SourceGeneratedReflectionDataProvider
  {
- TypeMethodInvokers = { [add] = invoker },
+ TypeMethodInvokers = new Dictionary<MethodInfo, Func<object?, object?[]?, object?>> { [add] = invoker },
  };
  var operations = new SourceGeneratedReflectionOperations(provider);
 
@@ -67,7 +67,7 @@ public void GetConstructorInvoker_CreatesInstance_WithoutActivator()
  ];
  var provider = new SourceGeneratedReflectionDataProvider
  {
- TypeConstructorsInvoker = { [typeof(Sample)] = invokers },
+ TypeConstructorsInvoker = new Dictionary<Type, SourceGeneratedReflectionDataProvider.ConstructorInvoker[]> { [typeof(Sample)] = invokers },
  };
  var operations = new SourceGeneratedReflectionOperations(provider);
 
@@ -99,7 +99,7 @@ public void GetConstructorInvoker_FallsBackToReflection_WhenArgumentsDoNotMatchR
  ];
  var provider = new SourceGeneratedReflectionDataProvider
  {
- TypeConstructorsInvoker = { [typeof(Sample)] = invokers },
+ TypeConstructorsInvoker = new Dictionary<Type, SourceGeneratedReflectionDataProvider.ConstructorInvoker[]> { [typeof(Sample)] = invokers },
  };
  var operations = new SourceGeneratedReflectionOperations(provider);
 
@@ -119,7 +119,7 @@ public void GetPropertySetter_AssignsValue_WithoutSetValue()
 
  var provider = new SourceGeneratedReflectionDataProvider
  {
- TypePropertySetters = { [property] = setter },
+ TypePropertySetters = new Dictionary<PropertyInfo, Action<object?, object?>> { [property] = setter },
  };
  var operations = new SourceGeneratedReflectionOperations(provider);