Phase 5: generated-client vs generated-server integration harness

README.md

@@ -20,7 +20,7 @@ See [`docs/PLAN.md`](docs/PLAN.md) for the full phased plan and
 | 2 | Codegen plugin + type generation | ✅ Done — types generated for both fixtures, golden+compile+behavior tested ([docs/design/codegen-architecture.md](docs/design/codegen-architecture.md)) |
 | 3 | Client generation (restJson1 + rpcv2Cbor) | ✅ Done — serde + clients for both protocols with typed errors ([docs/generated-types.md](docs/generated-types.md)); ~240 official protocol conformance cases green (documented exclusions) |
 | 4 | Server generation (restJson1 + rpcv2Cbor) | ✅ Done — handlers, routing, serde, all HTTP bindings incl. `@httpPayload`/`@httpPrefixHeaders`, constraint validation, parser strictness, content negotiation; ~1,175 official conformance cases green ([docs/server-guide.md](docs/server-guide.md)) |
-| 5 | Generated-client ↔ generated-server integration harness | Not started |
+| 5 | Generated-client ↔ generated-server integration harness | ✅ Done — every fixture ships a generated integration suite: seeded random round-trips over loopback and real sockets, per-error mapping, unknown-member tolerance, mutation-checked ([docs/design/integration-testing.md](docs/design/integration-testing.md)) |
 | 6 | Bazel rules, CLI, packaging (BCR + Maven Central), docs site | Not started |
 | 7 | Hardening, fuzzing, v0.1.0 | Not started |
 | 8 | Bidirectional streaming (event streams, WebSockets) | Not started |

codegen/smithy-cpp-codegen/build.gradle.kts

@@ -20,6 +20,7 @@ fun registerFixtureTask(
         "--runtime-target", "//runtime:core",
         "--output", File(repoRoot, outputPath).absolutePath,
         "--tests-package", "//" + outputPath,
+        "--integration-tests", "true",
     )
     doFirst {
         project.delete(File(repoRoot, outputPath))
@@ -42,6 +43,24 @@ val generateCafeFixture = registerFixtureTask(
     "examples/cafe/generated",
 )
 
+// The kitchen-sink round-trip fixture: one model, two protocol variants, so the
+// Phase 5 integration matrix covers REST and RPC with the same shapes.
+val generateRoundTripRestFixture = registerFixtureTask(
+    "generateRoundTripRestFixture",
+    "examples/roundtrip/model/roundtrip.smithy",
+    "example.roundtrip#RoundTripRest",
+    "example::roundtrip::rest",
+    "examples/roundtrip/rest/generated",
+)
+
+val generateRoundTripRpcFixture = registerFixtureTask(
+    "generateRoundTripRpcFixture",
+    "examples/roundtrip/model/roundtrip.smithy",
+    "example.roundtrip#RoundTripRpc",
+    "example::roundtrip::rpc",
+    "examples/roundtrip/rpc/generated",
+)
+
 // The official protocol-test suite models, kept off the main runtime classpath
 // so ordinary fixture generation doesn't assemble them.
 val protocolTestModels: Configuration by configurations.creating
@@ -131,7 +150,12 @@ tasks.register("generateProtocolTests") {
 tasks.register("generateFixtures") {
     group = "smithy-cpp"
     description = "Regenerates all checked-in generated code under examples/ (the goldens)"
-    dependsOn(generateWeatherFixture, generateCafeFixture)
+    dependsOn(
+        generateWeatherFixture,
+        generateCafeFixture,
+        generateRoundTripRestFixture,
+        generateRoundTripRpcFixture,
+    )
 }
 
 tasks.withType<Test>().configureEach {

codegen/smithy-cpp-codegen/src/main/java/io/smithycpp/codegen/CppCodegenRunner.java

@@ -41,6 +41,7 @@ public static void main(String[] args) {
     String output = null;
     String testsPackage = null;
     boolean malformedTests = false;
+    boolean integrationTests = false;
     List<String> omitOperations = new ArrayList<>();
     for (int i = 0; i + 1 < args.length; i += 2) {
       switch (args[i]) {
@@ -52,6 +53,7 @@ public static void main(String[] args) {
         case "--tests-package" -> testsPackage = args[i + 1];
         case "--omit-operation" -> omitOperations.add(args[i + 1]);
         case "--malformed-tests" -> malformedTests = Boolean.parseBoolean(args[i + 1]);
+        case "--integration-tests" -> integrationTests = Boolean.parseBoolean(args[i + 1]);
         default -> throw new IllegalArgumentException("unknown argument: " + args[i]);
       }
     }
@@ -87,6 +89,9 @@ public static void main(String[] args) {
     if (malformedTests) {
       settings.withMember("malformedTests", true);
     }
+    if (integrationTests) {
+      settings.withMember("integrationTests", true);
+    }
 
     PluginContext context =
         PluginContext.builder()

codegen/smithy-cpp-codegen/src/main/java/io/smithycpp/codegen/CppSettings.java

@@ -22,18 +22,21 @@ public final class CppSettings {
   private final String runtimeTarget;
   private final String testsPackage;
   private final boolean malformedTests;
+  private final boolean integrationTests;
 
   private CppSettings(
       ShapeId service,
       String namespace,
       String runtimeTarget,
       String testsPackage,
-      boolean malformedTests) {
+      boolean malformedTests,
+      boolean integrationTests) {
     this.service = service;
     this.namespace = namespace;
     this.runtimeTarget = runtimeTarget;
     this.testsPackage = testsPackage;
     this.malformedTests = malformedTests;
+    this.integrationTests = integrationTests;
   }
 
   public static CppSettings fromNode(ObjectNode node) {
@@ -43,11 +46,13 @@ public static CppSettings fromNode(ObjectNode node) {
         node.getStringMemberOrDefault("runtimeTarget", "@smithy_cpp//runtime:core");
     String testsPackage = node.getStringMemberOrDefault("testsPackage", null);
     boolean malformedTests = node.getBooleanMemberOrDefault("malformedTests", false);
+    boolean integrationTests = node.getBooleanMemberOrDefault("integrationTests", false);
     if (!namespace.matches("[A-Za-z_][A-Za-z0-9_]*(::[A-Za-z_][A-Za-z0-9_]*)*")) {
       throw new IllegalArgumentException(
           "cpp-codegen: 'namespace' must be a C++ namespace like a::b, got: " + namespace);
     }
-    return new CppSettings(service, namespace, runtimeTarget, testsPackage, malformedTests);
+    return new CppSettings(
+        service, namespace, runtimeTarget, testsPackage, malformedTests, integrationTests);
   }
 
   public ShapeId service() {
@@ -110,6 +115,15 @@ public boolean malformedTests() {
     return malformedTests;
   }
 
+  /**
+   * Whether to generate tests/integration_test.cc: generated client vs generated server over
+   * loopback and real sockets with random round-trips (PLAN Phase 5). Per-module, like the
+   * conformance suites.
+   */
+  public boolean integrationTests() {
+    return integrationTests;
+  }
+
   @Override
   public boolean equals(Object other) {
     if (!(other instanceof CppSettings that)) {
@@ -119,11 +133,13 @@ public boolean equals(Object other) {
         && namespace.equals(that.namespace)
         && runtimeTarget.equals(that.runtimeTarget)
         && Objects.equals(testsPackage, that.testsPackage)
-        && malformedTests == that.malformedTests;
+        && malformedTests == that.malformedTests
+        && integrationTests == that.integrationTests;
   }
 
   @Override
   public int hashCode() {
-    return Objects.hash(service, namespace, runtimeTarget, testsPackage, malformedTests);
+    return Objects.hash(
+        service, namespace, runtimeTarget, testsPackage, malformedTests, integrationTests);
   }
 }

codegen/smithy-cpp-codegen/src/main/java/io/smithycpp/codegen/DirectedCppCodegen.java

@@ -91,7 +91,12 @@ public void generateService(GenerateServiceDirective<CppContext, CppSettings> di
                     hasMalformedTests)
                 .run();
           }
-          TestsBuildFileGenerator.run(directive.context(), hasProtocolTests, hasMalformedTests);
+          boolean hasIntegrationTests = directive.settings().integrationTests();
+          if (hasIntegrationTests) {
+            new IntegrationTestGenerator(directive.context(), service, protocol, operations).run();
+          }
+          TestsBuildFileGenerator.run(
+              directive.context(), hasProtocolTests, hasMalformedTests, hasIntegrationTests);
         }
       }
     }