Propagate StatusException trailers in GrpcExceptionHandlerInterceptor

Ensure that trailers from StatusException returned by
GrpcExceptionHandler are used when closing the ServerCall.

Closes: gh-332

Signed-off-by: Andrey Litvitski <[email protected]>

Author: therepanic

spring-grpc-core/src/main/java/org/springframework/grpc/server/exception/GrpcExceptionHandlerInterceptor.java

@@ -44,6 +44,7 @@
  * returns a null.
  *
  * @author Dave Syer
+ * @author Andrey Litvitski
  * @see ServerInterceptor
  * @see GrpcExceptionHandler
  */
@@ -81,7 +82,7 @@ public <ReqT, RespT> Listener<ReqT> interceptCall(ServerCall<ReqT, RespT> call,
 			this.logger.trace("Failed to start exception handler call", t);
 			StatusException statusEx = fallbackHandler.handleException(t);
 			exceptionHandledServerCall.close(statusEx != null ? statusEx.getStatus() : Status.fromThrowable(t),
-					headers(t));
+					headers(statusEx != null ? statusEx : t));
 			return new Listener<>() {
 			};
 		}

spring-grpc-core/src/test/java/org/springframework/grpc/server/exception/GrpcExceptionHandlerInterceptorTests.java

@@ -17,11 +17,35 @@
 package org.springframework.grpc.server.exception;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
 
 import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentCaptor;
 
 import org.springframework.grpc.server.exception.GrpcExceptionHandlerInterceptor.FallbackHandler;
 
+import com.google.protobuf.Any;
+import com.google.protobuf.Empty;
+import com.google.rpc.Code;
+import com.google.rpc.Status;
+import io.grpc.Metadata;
+import io.grpc.MethodDescriptor;
+import io.grpc.ServerCall;
+import io.grpc.ServerCallHandler;
+import io.grpc.ServerInterceptor;
+import io.grpc.StatusException;
+import io.grpc.protobuf.ProtoUtils;
+import io.grpc.protobuf.StatusProto;
+
+/**
+ * Tests for {@link GrpcExceptionHandlerInterceptor}.
+ *
+ * @author Dave Syer
+ * @author Andrey Litvitski
+ */
 public class GrpcExceptionHandlerInterceptorTests {
 
 	@Test
@@ -30,4 +54,38 @@ void testNullStatusHandled() {
 			.isNotNull();
 	}
 
+	@Test
+	void propagatesTrailersFromStatusExceptionWhenStartCallThrows() {
+		Status statusWithDetails = Status.newBuilder()
+			.setCode(Code.PERMISSION_DENIED_VALUE)
+			.setMessage("access denied")
+			.addDetails(Any.pack(Empty.getDefaultInstance()))
+			.build();
+		StatusException statusEx = StatusProto.toStatusException(statusWithDetails);
+		GrpcExceptionHandler handler = ex -> statusEx;
+		ServerInterceptor interceptor = new GrpcExceptionHandlerInterceptor(handler);
+		@SuppressWarnings("unchecked")
+		ServerCall<Empty, Empty> call = mock(ServerCall.class);
+		MethodDescriptor<Empty, Empty> method = MethodDescriptor.<Empty, Empty>newBuilder()
+			.setType(MethodDescriptor.MethodType.UNARY)
+			.setFullMethodName("test/Test")
+			.setRequestMarshaller(ProtoUtils.marshaller(Empty.getDefaultInstance()))
+			.setResponseMarshaller(ProtoUtils.marshaller(Empty.getDefaultInstance()))
+			.build();
+		when(call.getMethodDescriptor()).thenReturn(method);
+		ServerCallHandler<Empty, Empty> next = (c, headers) -> {
+			throw new RuntimeException("boom");
+		};
+		interceptor.interceptCall(call, new Metadata(), next);
+		ArgumentCaptor<io.grpc.Status> statusCaptor = ArgumentCaptor.forClass(io.grpc.Status.class);
+		ArgumentCaptor<Metadata> trailersCaptor = ArgumentCaptor.forClass(Metadata.class);
+		verify(call, times(1)).close(statusCaptor.capture(), trailersCaptor.capture());
+		io.grpc.Status closedStatus = statusCaptor.getValue();
+		Metadata closedTrailers = trailersCaptor.getValue();
+		assertThat(closedStatus.getCode()).isEqualTo(io.grpc.Status.Code.PERMISSION_DENIED);
+		Status extracted = StatusProto.fromThrowable(new StatusException(closedStatus, closedTrailers));
+		assertThat(extracted).isNotNull();
+		assertThat(extracted).isEqualTo(statusWithDetails);
+	}
+
 }