From 29cf2ada75ea60ab29c367cf3b90d7f119a37e8b Mon Sep 17 00:00:00 2001
From: Novo <eunovo9@gmail.com>
Date: Wed, 1 Oct 2025 17:24:06 +0200
Subject: [PATCH 1/2] test default PassField impl handles output parameters

Tests that output parameter result is captured from server call and added to response.
---
 test/mp/test/foo.capnp | 1 +
 test/mp/test/foo.h     | 1 +
 test/mp/test/test.cpp  | 3 +++
 3 files changed, 5 insertions(+)

diff --git a/test/mp/test/foo.capnp b/test/mp/test/foo.capnp
index 75e4617d..d42bba05 100644
--- a/test/mp/test/foo.capnp
+++ b/test/mp/test/foo.capnp
@@ -13,6 +13,7 @@ $Proxy.includeTypes("mp/test/foo-types.h");
 
 interface FooInterface $Proxy.wrap("mp::test::FooImplementation") {
     add @0 (a :Int32, b :Int32) -> (result :Int32);
+    addOut @19 (a :Int32, b :Int32) -> (ret :Int32);
     mapSize @1 (map :List(Pair(Text, Text))) -> (result :Int32);
     pass @2 (arg :FooStruct) -> (result :FooStruct);
     raise @3 (arg :FooStruct) -> (error :FooStruct $Proxy.exception("mp::test::FooStruct"));
diff --git a/test/mp/test/foo.h b/test/mp/test/foo.h
index 70bf4ff1..dbbce36a 100644
--- a/test/mp/test/foo.h
+++ b/test/mp/test/foo.h
@@ -62,6 +62,7 @@ class FooImplementation
 {
 public:
     int add(int a, int b) { return a + b; }
+    void addOut(int a, int b, int& out) { out = a + b; }
     int mapSize(const std::map<std::string, std::string>& map) { return map.size(); }
     FooStruct pass(FooStruct foo) { return foo; }
     void raise(FooStruct foo) { throw foo; }
diff --git a/test/mp/test/test.cpp b/test/mp/test/test.cpp
index 225d00d5..35ca4d6c 100644
--- a/test/mp/test/test.cpp
+++ b/test/mp/test/test.cpp
@@ -113,6 +113,9 @@ KJ_TEST("Call FooInterface methods")
     ProxyClient<messages::FooInterface>* foo = setup.client.get();
 
     KJ_EXPECT(foo->add(1, 2) == 3);
+    int ret;
+    foo->addOut(3, 4, ret);
+    KJ_EXPECT(ret == 7);
 
     FooStruct in;
     in.name = "name";

From 6db669628387b481b0d5726f011eb45025f31ccf Mon Sep 17 00:00:00 2001
From: Novo <eunovo9@gmail.com>
Date: Wed, 1 Oct 2025 22:02:32 +0200
Subject: [PATCH 2/2] test In|Out parameter

---
 test/mp/test/foo.capnp | 1 +
 test/mp/test/foo.h     | 1 +
 test/mp/test/test.cpp  | 2 ++
 3 files changed, 4 insertions(+)

diff --git a/test/mp/test/foo.capnp b/test/mp/test/foo.capnp
index d42bba05..67bc8e4f 100644
--- a/test/mp/test/foo.capnp
+++ b/test/mp/test/foo.capnp
@@ -14,6 +14,7 @@ $Proxy.includeTypes("mp/test/foo-types.h");
 interface FooInterface $Proxy.wrap("mp::test::FooImplementation") {
     add @0 (a :Int32, b :Int32) -> (result :Int32);
     addOut @19 (a :Int32, b :Int32) -> (ret :Int32);
+    addInOut @20 (x :Int32, sum :Int32) -> (sum :Int32);
     mapSize @1 (map :List(Pair(Text, Text))) -> (result :Int32);
     pass @2 (arg :FooStruct) -> (result :FooStruct);
     raise @3 (arg :FooStruct) -> (error :FooStruct $Proxy.exception("mp::test::FooStruct"));
diff --git a/test/mp/test/foo.h b/test/mp/test/foo.h
index dbbce36a..8415f6f0 100644
--- a/test/mp/test/foo.h
+++ b/test/mp/test/foo.h
@@ -63,6 +63,7 @@ class FooImplementation
 public:
     int add(int a, int b) { return a + b; }
     void addOut(int a, int b, int& out) { out = a + b; }
+    void addInOut(int x, int& sum) { sum += x; }
     int mapSize(const std::map<std::string, std::string>& map) { return map.size(); }
     FooStruct pass(FooStruct foo) { return foo; }
     void raise(FooStruct foo) { throw foo; }
diff --git a/test/mp/test/test.cpp b/test/mp/test/test.cpp
index 35ca4d6c..9273dfae 100644
--- a/test/mp/test/test.cpp
+++ b/test/mp/test/test.cpp
@@ -116,6 +116,8 @@ KJ_TEST("Call FooInterface methods")
     int ret;
     foo->addOut(3, 4, ret);
     KJ_EXPECT(ret == 7);
+    foo->addInOut(3, ret);
+    KJ_EXPECT(ret == 10);
 
     FooStruct in;
     in.name = "name";