fix(.net): missing dynamic type checking for collection-nested unions (#3720)

The .NET runtime type checking was not checking type unions that are nested within a collection (list or map), although this is necessary since the `is <type>` guard does not allow making any assumption about the contents of the collection. This adds the missing checks, and replaces the guard clauses with a `switch` statement using pattern matching, resulting in somewhat more elegant code (also with better `null` safety). --- By submitting this pull request, I confirm that my contribution is made under the terms of the [Apache 2.0 license]. [Apache 2.0 license]: https://www.apache.org/licenses/LICENSE-2.0

Author: RomainMuller

packages/@jsii/dotnet-runtime-test/test/Amazon.JSII.Runtime.IntegrationTests/TypeCheckingTests.cs

@@ -73,5 +73,29 @@ public void AnonymousObjectIsValid()
  Assert.IsType<AnonymousObject>(anonymousObject);
  Assert.Equal("A", UseOptions.Consume(anonymousObject));
  }
+
+ [Fact(DisplayName = Prefix + nameof(NestedUnion))]
+ public void NestedUnion()
+ {
+ var exception1 = Assert.Throws<System.ArgumentException>(() =>
+ new ClassWithNestedUnion(new object[] { 1337.42 }));
+ Assert.Equal("Expected argument unionProperty[0] to be one of: System.Collections.Generic.IDictionary<string, object>, object[]; received System.Double (Parameter 'unionProperty')", exception1.Message);
+
+ var exception2 = Assert.Throws<System.ArgumentException>(() =>
+ new ClassWithNestedUnion(new object[]
+ { new object[] { new StructA { RequiredString = "present" }, 1337 } }));
+ Assert.Equal("Expected argument unionProperty[0][1] to be one of: Amazon.JSII.Tests.CalculatorNamespace.IStructA, Amazon.JSII.Tests.CalculatorNamespace.IStructB; received System.Int32 (Parameter 'unionProperty')", exception2.Message);
+
+ var exception3 = Assert.Throws<System.ArgumentException>(() =>
+ new ClassWithNestedUnion(new object[]
+ {
+ new Dictionary<string, object>
+ {
+ { "good", new StructA { RequiredString = "present" } },
+ { "bad", "Not a StructA or StructB" }
+ }
+ }));
+ Assert.Equal("Expected argument unionProperty[0][\"bad\"] to be one of: Amazon.JSII.Tests.CalculatorNamespace.IStructA, Amazon.JSII.Tests.CalculatorNamespace.IStructB; received System.String (Parameter 'unionProperty')", exception3.Message);
+ }
  }
 }

packages/jsii-calc/lib/compliance.ts

@@ -3074,3 +3074,11 @@ export class ClassWithCollectionOfUnions {
 export interface StructWithCollectionOfUnionts {
  readonly unionProperty: Array<Record<string, StructA | StructB>>;
 }
+
+export class ClassWithNestedUnion {
+ public constructor(
+ public unionProperty: Array<
+ Array<StructA | StructB> | Record<string, StructA | StructB>
+ >,
+ ) {}
+}

packages/jsii-calc/test/assembly.jsii

@@ -2976,6 +2976,136 @@
  ],
  "symbolId": "lib/compliance:ClassWithMutableObjectLiteralProperty"
  },
+ "jsii-calc.ClassWithNestedUnion": {
+ "assembly": "jsii-calc",
+ "docs": {
+ "stability": "stable"
+ },
+ "fqn": "jsii-calc.ClassWithNestedUnion",
+ "initializer": {
+ "docs": {
+ "stability": "stable"
+ },
+ "locationInModule": {
+ "filename": "lib/compliance.ts",
+ "line": 3079
+ },
+ "parameters": [
+ {
+ "name": "unionProperty",
+ "type": {
+ "collection": {
+ "elementtype": {
+ "union": {
+ "types": [
+ {
+ "collection": {
+ "elementtype": {
+ "union": {
+ "types": [
+ {
+ "fqn": "jsii-calc.StructA"
+ },
+ {
+ "fqn": "jsii-calc.StructB"
+ }
+ ]
+ }
+ },
+ "kind": "map"
+ }
+ },
+ {
+ "collection": {
+ "elementtype": {
+ "union": {
+ "types": [
+ {
+ "fqn": "jsii-calc.StructA"
+ },
+ {
+ "fqn": "jsii-calc.StructB"
+ }
+ ]
+ }
+ },
+ "kind": "array"
+ }
+ }
+ ]
+ }
+ },
+ "kind": "array"
+ }
+ }
+ }
+ ]
+ },
+ "kind": "class",
+ "locationInModule": {
+ "filename": "lib/compliance.ts",
+ "line": 3078
+ },
+ "name": "ClassWithNestedUnion",
+ "properties": [
+ {
+ "docs": {
+ "stability": "stable"
+ },
+ "locationInModule": {
+ "filename": "lib/compliance.ts",
+ "line": 3080
+ },
+ "name": "unionProperty",
+ "type": {
+ "collection": {
+ "elementtype": {
+ "union": {
+ "types": [
+ {
+ "collection": {
+ "elementtype": {
+ "union": {
+ "types": [
+ {
+ "fqn": "jsii-calc.StructA"
+ },
+ {
+ "fqn": "jsii-calc.StructB"
+ }
+ ]
+ }
+ },
+ "kind": "map"
+ }
+ },
+ {
+ "collection": {
+ "elementtype": {
+ "union": {
+ "types": [
+ {
+ "fqn": "jsii-calc.StructA"
+ },
+ {
+ "fqn": "jsii-calc.StructB"
+ }
+ ]
+ }
+ },
+ "kind": "array"
+ }
+ }
+ ]
+ }
+ },
+ "kind": "array"
+ }
+ }
+ }
+ ],
+ "symbolId": "lib/compliance:ClassWithNestedUnion"
+ },
  "jsii-calc.ClassWithPrivateConstructorAndAutomaticProperties": {
  "assembly": "jsii-calc",
  "docs": {
@@ -18001,5 +18131,5 @@
  }
  },
  "version": "3.20.120",
- "fingerprint": "w4jjSmxpafX7pHdksFL0F5FZxa/zM6MB8oFCANIU05k="
+ "fingerprint": "LBLJQQycukWu6zWQmp2/IbKS/Sfd+4e2zWrX+1KA+Aw="
 }