Add httpResponseCode Prelude trait

docs/source/1.0/spec/core/http-traits.rst

@@ -805,6 +805,23 @@ Serialization rules:
     Smithy models SHOULD carefully consider the maximum allowed length of each
     member that is bound to an HTTP query string or path.
 
+.. _httpResponseCode-trait:
+
+``httpResponseCode`` trait
+==========================
+
+Summary
+    Indicates that the structure member represents an HTTP response
+    status code.
+Trait selector
+    ``structure > member :test(> integer)``
+Value type
+    Annotation trait.
+
+The value MAY differ from the HTTP status code provided on the response.
+Explicitly modeling this as a field can be helpful for services that wish to
+provide different response codes for an operation, like 200 or 201 for a PUT
+operation.
 
 .. _cors-trait:
 

smithy-model/src/main/java/software/amazon/smithy/model/traits/HttpResponseCodeTrait.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.smithy.model.traits;
+
+import software.amazon.smithy.model.node.Node;
+import software.amazon.smithy.model.node.ObjectNode;
+import software.amazon.smithy.model.shapes.ShapeId;
+
+/**
+ * Indicates that the structure member represents the HTTP response
+ * status code. This MAY differ from the HTTP status code provided
+ * in the response.
+ */
+public final class HttpResponseCodeTrait  extends AnnotationTrait {
+    public static final ShapeId ID = ShapeId.from("smithy.api#httpResponseCode");
+
+    public HttpResponseCodeTrait(ObjectNode node) {
+        super(ID, node);
+    }
+
+    public HttpResponseCodeTrait() {
+        this(Node.objectNode());
+    }
+
+    public static final class Provider extends AnnotationTrait.Provider<HttpResponseCodeTrait> {
+        public Provider() {
+            super(ID, HttpResponseCodeTrait::new);
+        }
+    }
+}

smithy-model/src/main/resources/META-INF/services/software.amazon.smithy.model.traits.TraitService

@@ -18,6 +18,7 @@ software.amazon.smithy.model.traits.HttpLabelTrait$Provider
 software.amazon.smithy.model.traits.HttpPayloadTrait$Provider
 software.amazon.smithy.model.traits.HttpPrefixHeadersTrait$Provider
 software.amazon.smithy.model.traits.HttpQueryTrait$Provider
+software.amazon.smithy.model.traits.HttpResponseCodeTrait$Provider
 software.amazon.smithy.model.traits.HttpTrait$Provider
 software.amazon.smithy.model.traits.IdempotencyTokenTrait$Provider
 software.amazon.smithy.model.traits.IdempotentTrait$Provider

smithy-model/src/main/resources/software/amazon/smithy/model/loader/prelude.smithy

@@ -574,6 +574,14 @@ structure httpPayload {}
 @tags(["diff.error.const"])
 integer httpError
 
+/// Indicates that the structure member represents the HTTP response
+/// status code. The value MAY differ from the HTTP status code provided
+/// on the response.
+@trait(selector: "structure > member :test(> integer)",
+        structurallyExclusive: "member")
+@tags(["diff.error.const"])
+structure httpResponseCode {}
+
 /// Defines how a service supports cross-origin resource sharing.
 @trait(selector: "service")
 @tags(["diff.error.remove"])

smithy-model/src/test/java/software/amazon/smithy/model/traits/HttpResponseCodeTraitTest.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.smithy.model.traits;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.instanceOf;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Optional;
+import org.junit.jupiter.api.Test;
+import software.amazon.smithy.model.node.Node;
+import software.amazon.smithy.model.shapes.ShapeId;
+
+public class HttpResponseCodeTraitTest {
+    @Test
+    public void loadsTrait() {
+        TraitFactory provider = TraitFactory.createServiceFactory();
+        Optional<Trait> trait = provider.createTrait(
+                ShapeId.from("smithy.api#httpResponseCode"), ShapeId.from("ns.qux#Foo$bar"), Node.objectNode());
+
+        assertTrue(trait.isPresent());
+        assertThat(trait.get(), instanceOf(HttpResponseCodeTrait.class));
+        assertThat(trait.get().toNode(), equalTo(Node.objectNode()));
+    }
+}