Merge pull request #317 from soundcloud/support-proto3-optional

Add support for 'optional' in proto3 files

README.md

@@ -22,3 +22,6 @@ Please ensure that `sbt scalafmtCheckAll +test scripted` passes when submitting
 
 * IntelliJ [doesn't run plugins][intellij] during project build. Before importing,
  `sbt compile` may be necessary.
+
+* In order to run the full test suite (i.e. the unit tests & the end-to-end tests
+ for code-generation) use `sbt +test scripted`

codegen/src/main/scala/com/soundcloud/twinagle/codegen/ServerClientCodeGenerator.scala

@@ -43,7 +43,8 @@ object ServerClientCodeGenerator extends CodeGenApp {
           for {
             file        <- request.filesToGenerate
             serviceFile <- generateServiceFiles(file, implicits)
-          } yield serviceFile
+          } yield serviceFile,
+          supportedFeatures = Set(CodeGeneratorResponse.Feature.FEATURE_PROTO3_OPTIONAL)
         )
       case Left(error) =>
         CodeGenResponse.fail(error)

codegen/src/sbt-test/generator/e2e/src/main/protobuf/optional_fields.proto

@@ -0,0 +1,14 @@
+// A small test case for support of optional fields in proto3.
+
+syntax = "proto3";
+
+package proto.test;
+
+message IHaveOptionalFields {
+  optional int32 maybe_int = 1;
+  optional string maybe_string = 2;
+}
+
+service OptionalFieldsTest {
+  rpc DoSomething(IHaveOptionalFields) returns (IHaveOptionalFields);
+}

codegen/src/sbt-test/generator/e2e/src/test/scala/proto/test/OptionalFieldsSpec.scala

@@ -0,0 +1,33 @@
+package proto.test
+
+import com.twitter.util.Future
+import com.soundcloud.twinagle.ServerBuilder
+
+import org.specs2.mutable.Specification
+
+class OptionalFieldsSpec extends Specification {
+  // if this compiles, we're good
+  "Proto files with optional scalar values are generated correctly" in {
+    val svc = new OptionalFieldsTestService {
+      override def doSomething(req: IHaveOptionalFields): Future[IHaveOptionalFields] = {
+        iTakeAnOptionInt(req.maybeInt)
+        iTakeAnOptionString(req.maybeString)
+        Future.value(req)
+      }
+
+      @annotation.nowarn
+      private def iTakeAnOptionInt[T](a: T)(implicit ev: T =:= Option[Int]): Unit = ()
+
+      @annotation.nowarn
+      private def iTakeAnOptionString[T](a: T)(implicit ev: T =:= Option[String]): Unit = ()
+    }
+
+    val httpService = ServerBuilder()
+      .register(svc)
+      .build
+
+    new OptionalFieldsTestClientProtobuf(httpService)
+    new OptionalFieldsTestClientJson(httpService)
+    ok
+  }
+}

codegen/src/sbt-test/generator/e2e/src/test/scala/twitch/twirp/example/haberdasher/HaberdasherSpec.scala

@@ -14,7 +14,7 @@ class HaberdasherSpec extends Specification {
           Hat(
             size = size.inches,
             color = "brown",
-            name = "bowler"
+            name = "bowler",
           )
         )
       } else {