fix: Properly SerDe recusive union shapes (enums) (#474)

* Prevents Union shapes from being boxed during preprocessing

* Fixes up tests

Author: Ed Paulosky

smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/model/RecursiveShapeBoxer.kt

@@ -12,14 +12,15 @@ import software.amazon.smithy.model.shapes.MapShape
 import software.amazon.smithy.model.shapes.MemberShape
 import software.amazon.smithy.model.shapes.SetShape
 import software.amazon.smithy.model.shapes.Shape
+import software.amazon.smithy.model.shapes.UnionShape
 import software.amazon.smithy.model.transform.ModelTransformer
 import software.amazon.smithy.swift.codegen.customtraits.SwiftBoxTrait
 
 object RecursiveShapeBoxer {
     /**
      * Transform a model which may contain recursive shapes into a model annotated with [SwiftBoxTrait]
      *
-     * When recursive shapes do NOT go through a List, Map, or Set, they must be boxed in Swift. This function will
+     * When recursive shapes do NOT go through a List, Map, Union, or Set, they must be boxed in Swift. This function will
      * iteratively find loops & add the `SwiftBoxTrait` trait in a deterministic way until it reaches a fixed point.
      *
      * This function MUST be deterministic (always choose the same shapes to `Box`). If it is not, that is a bug. Even so
@@ -84,6 +85,7 @@ object RecursiveShapeBoxer {
             when (it) {
                 is ListShape,
                 is MapShape,
+                is UnionShape,
                 is SetShape -> true
                 else -> it.hasTrait(SwiftBoxTrait::class.java)
             }

smithy-swift-codegen/src/test/kotlin/UnionEncodeGeneratorTests.kt

@@ -6,15 +6,27 @@
 import io.kotest.matchers.string.shouldContainOnlyOnce
 import org.junit.jupiter.api.Assertions
 import org.junit.jupiter.api.Test
+import software.amazon.smithy.model.Model
 import software.amazon.smithy.swift.codegen.model.AddOperationShapes
+import software.amazon.smithy.swift.codegen.model.HashableShapeTransformer
+import software.amazon.smithy.swift.codegen.model.NestedShapeTransformer
+import software.amazon.smithy.swift.codegen.model.RecursiveShapeBoxer
 
 class UnionEncodeGeneratorTests {
     var model = javaClass.getResource("http-binding-protocol-generator-test.smithy").asSmithy()
     private fun newTestContext(): TestContext {
-        val settings = model.defaultSettings()
-        model = AddOperationShapes.execute(model, settings.getService(model), settings.moduleName)
+        model = preprocessModel(model)
         return model.newTestContext()
     }
+    private fun preprocessModel(model: Model): Model {
+        val settings = model.defaultSettings()
+        var resolvedModel = model
+        resolvedModel = AddOperationShapes.execute(resolvedModel, settings.getService(resolvedModel), settings.moduleName)
+        resolvedModel = RecursiveShapeBoxer.transform(resolvedModel)
+        resolvedModel = HashableShapeTransformer.transform(resolvedModel)
+        resolvedModel = NestedShapeTransformer.transform(resolvedModel, settings.getService(resolvedModel))
+        return resolvedModel
+    }
     val newTestContext = newTestContext()
     init {
         newTestContext.generator.generateSerializers(newTestContext.generationCtx)
@@ -60,7 +72,7 @@ class UnionEncodeGeneratorTests {
         contents.shouldSyntacticSanityCheck()
         val expectedContents =
             """
-            extension MyUnion: Swift.Codable {
+            extension ExampleClientTypes.MyUnion: Swift.Codable {
                 enum CodingKeys: Swift.String, Swift.CodingKey {
                     case blobvalue = "blobValue"
                     case booleanvalue = "booleanValue"
@@ -141,7 +153,7 @@ class UnionEncodeGeneratorTests {
                         self = .inheritedtimestamp(inheritedtimestamp)
                         return
                     }
-                    let enumvalueDecoded = try values.decodeIfPresent(FooEnum.self, forKey: .enumvalue)
+                    let enumvalueDecoded = try values.decodeIfPresent(ExampleClientTypes.FooEnum.self, forKey: .enumvalue)
                     if let enumvalue = enumvalueDecoded {
                         self = .enumvalue(enumvalue)
                         return
@@ -174,7 +186,7 @@ class UnionEncodeGeneratorTests {
                         self = .mapvalue(mapvalue)
                         return
                     }
-                    let structurevalueDecoded = try values.decodeIfPresent(GreetingWithErrorsOutput.self, forKey: .structurevalue)
+                    let structurevalueDecoded = try values.decodeIfPresent(ExampleClientTypes.GreetingWithErrorsOutput.self, forKey: .structurevalue)
                     if let structurevalue = structurevalueDecoded {
                         self = .structurevalue(structurevalue)
                         return
@@ -185,4 +197,48 @@ class UnionEncodeGeneratorTests {
             """.trimIndent()
         contents.shouldContainOnlyOnce(expectedContents)
     }
+
+    @Test
+    fun `it generates codable conformance for a recursive union`() {
+        val contents = getModelFileContents("example", "IndirectEnum+Codable.swift", newTestContext.manifest)
+        contents.shouldSyntacticSanityCheck()
+        val expectedContents =
+            """
+            extension ExampleClientTypes.IndirectEnum: Swift.Codable {
+                enum CodingKeys: Swift.String, Swift.CodingKey {
+                    case other
+                    case sdkUnknown
+                    case some
+                }
+
+                public func encode(to encoder: Swift.Encoder) throws {
+                    var container = encoder.container(keyedBy: CodingKeys.self)
+                    switch self {
+                        case let .other(other):
+                            try container.encode(other, forKey: .other)
+                        case let .some(some):
+                            try container.encode(some, forKey: .some)
+                        case let .sdkUnknown(sdkUnknown):
+                            try container.encode(sdkUnknown, forKey: .sdkUnknown)
+                    }
+                }
+
+                public init (from decoder: Swift.Decoder) throws {
+                    let values = try decoder.container(keyedBy: CodingKeys.self)
+                    let someDecoded = try values.decodeIfPresent(ExampleClientTypes.IndirectEnum.self, forKey: .some)
+                    if let some = someDecoded {
+                        self = .some(some)
+                        return
+                    }
+                    let otherDecoded = try values.decodeIfPresent(Swift.String.self, forKey: .other)
+                    if let other = otherDecoded {
+                        self = .other(other)
+                        return
+                    }
+                    self = .sdkUnknown("")
+                }
+            }
+            """.trimIndent()
+        contents.shouldContainOnlyOnce(expectedContents)
+    }
 }

smithy-swift-codegen/src/test/kotlin/serde/xml/UnionEncodeXMLGenerationTests.kt

@@ -74,8 +74,8 @@ class UnionEncodeXMLGenerationTests {
                             let datavalueDecoded = try containerValues.decode(ClientRuntime.Data.self, forKey: .datavalue)
                             self = .datavalue(datavalueDecoded)
                         case .unionvalue:
-                            let unionvalueDecoded = try containerValues.decode(Box<RestXmlProtocolClientTypes.XmlUnionShape>.self, forKey: .unionvalue)
-                            self = .unionvalue(unionvalueDecoded.value)
+                            let unionvalueDecoded = try containerValues.decode(RestXmlProtocolClientTypes.XmlUnionShape.self, forKey: .unionvalue)
+                            self = .unionvalue(unionvalueDecoded)
                         case .structvalue:
                             let structvalueDecoded = try containerValues.decode(RestXmlProtocolClientTypes.XmlNestedUnionStruct.self, forKey: .structvalue)
                             self = .structvalue(structvalueDecoded)

smithy-swift-codegen/src/test/resources/http-binding-protocol-generator-test.smithy

@@ -18,6 +18,7 @@ service Example {
         ListInput,
         MapInput,
         EnumInput,
+        IndirectEnumOperation,
         TimestampInput,
         BlobInput,
         EmptyInputAndEmptyOutput,
@@ -1029,6 +1030,12 @@ operation JsonUnions {
     output: UnionInputOutput,
 }
 
+@http(uri: "/IndirectEnumOperation", method: "POST")
+operation IndirectEnumOperation {
+    input: IndirectEnumInputOutput
+    output: IndirectEnumInputOutput
+}
+
 @timestampFormat("http-date")
 timestamp CommonTimestamp
 
@@ -1362,4 +1369,14 @@ structure IdempotencyTokenWithoutHttpPayloadTraitOnTokenInput {
     @httpHeader("token")
     @idempotencyToken
     token: String,
-}
+}
+
+union IndirectEnum {
+    some: IndirectEnum
+    other: String
+}
+
+structure IndirectEnumInputOutput {
+    value: IndirectEnum
+}
+