Netty Client does not detect when ALPN was not used

When I tried to reproduce the APLN silence failure, I expected the following change fails our tests, but not, all tests still passed.

diff --git a/interop-testing/src/test/java/io/grpc/testing/integration/Http2NettyTest.java b/interop-testing/src/test/java/io/grpc/testing/integration/Http2NettyTest.java
index 504c815..2ae8160 100644
--- a/interop-testing/src/test/java/io/grpc/testing/integration/Http2NettyTest.java
+++ b/interop-testing/src/test/java/io/grpc/testing/integration/Http2NettyTest.java
@@ -37,6 +37,7 @@ import io.grpc.transport.netty.GrpcSslContexts;
 import io.grpc.transport.netty.NettyChannelBuilder;
 import io.grpc.transport.netty.NettyServerBuilder;

+import io.netty.handler.ssl.ApplicationProtocolConfig;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
 import org.junit.runner.RunWith;
@@ -74,7 +75,8 @@ public class Http2NettyTest extends AbstractTransportTest {
       return NettyChannelBuilder
           .forAddress(TestUtils.testServerAddress(serverPort))
           .sslContext(GrpcSslContexts.forClient().trustManager(
-                  TestUtils.loadCert("ca.pem")).build())
+                  TestUtils.loadCert("ca.pem"))
+              .applicationProtocolConfig(ApplicationProtocolConfig.DISABLED).build())
           .build();
     } catch (Exception ex) {
       throw new RuntimeException(ex);

The problem itself is not a big deal, but investigating it may expose some hidden bugs.

[ejona86]

@buchgr, that’s a pretty weak error message. Very few people would be able to figure out what’s wrong in that case.

[buchgr]

When I disable ALPN all tests in Http2NettyTest fail with

io.grpc.testing.integration.Http2NettyTest > deadlineInPast FAILED
    io.grpc.StatusRuntimeException: UNAVAILABLE

        Caused by:
        javax.net.ssl.SSLException: engine closed

Isn’t that what we want, @ejona86 ?