interop-test: add test case for "pick_first" picking behavior (#5554)

New fields are added to the test protos according to grpc/grpc-proto#51

This test needs to be run in an environment where "pick_first" or "grpclb" with child policy "pick_first" is configured.

Author: zhangkun83

interop-testing/build.gradle

@@ -26,7 +26,8 @@ dependencies {
             libraries.truth
     compileOnly libraries.javax_annotation
     runtime libraries.opencensus_impl,
-            libraries.netty_tcnative
+            libraries.netty_tcnative,
+            project(':grpc-grpclb')
     testCompile project(':grpc-context').sourceSets.test.output,
             libraries.mockito
 }

interop-testing/src/main/java/io/grpc/testing/integration/AbstractInteropTest.java

@@ -491,6 +491,26 @@ public void serverCompressedUnary() throws Exception {
         Collections.singleton(goldenResponse));
   }
 
+  /**
+   * Assuming "pick_first" policy is used, tests that all requests are sent to the same server.
+   */
+  public void pickFirstUnary() throws Exception {
+    SimpleRequest request = SimpleRequest.newBuilder()
+        .setResponseSize(1)
+        .setFillServerId(true)
+        .setPayload(Payload.newBuilder().setBody(ByteString.copyFrom(new byte[1])))
+        .build();
+
+    SimpleResponse firstResponse = blockingStub.unaryCall(request);
+    // Increase the chance of all servers are connected, in case the channel should be doing
+    // round_robin instead.
+    Thread.sleep(5000);
+    for (int i = 0; i < 100; i++) {
+      SimpleResponse response = blockingStub.unaryCall(request);
+      assertThat(response.getServerId()).isEqualTo(firstResponse.getServerId());
+    }
+  }
+
   @Test
   public void serverStreaming() throws Exception {
     final StreamingOutputCallRequest request = StreamingOutputCallRequest.newBuilder()

interop-testing/src/main/java/io/grpc/testing/integration/TestCases.java

@@ -53,7 +53,8 @@ public enum TestCases {
   CANCEL_AFTER_BEGIN("cancel stream after starting it"),
   CANCEL_AFTER_FIRST_RESPONSE("cancel on first response"),
   TIMEOUT_ON_SLEEPING_SERVER("timeout before receiving a response"),
-  VERY_LARGE_REQUEST("very large request");
+  VERY_LARGE_REQUEST("very large request"),
+  PICK_FIRST_UNARY("all requests are sent to one server despite multiple servers are resolved");
 
   private final String description;
 

interop-testing/src/main/java/io/grpc/testing/integration/TestServiceClient.java

@@ -377,6 +377,11 @@ private void runTest(TestCases testCase) throws Exception {
         break;
       }
 
+      case PICK_FIRST_UNARY: {
+        tester.pickFirstUnary();
+        break;
+      }
+
       default:
         throw new IllegalArgumentException("Unknown test case: " + testCase);
     }

interop-testing/src/main/proto/grpc/testing/messages.proto

@@ -68,6 +68,9 @@ message SimpleRequest {
 
   // Whether the server should expect this request to be compressed.
   BoolValue expect_compressed = 8;
+
+  // Whether SimpleResponse should include server_id.
+  bool fill_server_id = 9;
 }
 
 // Unary response, as configured by the request.
@@ -79,6 +82,9 @@ message SimpleResponse {
   string username = 2;
   // OAuth scope.
   string oauth_scope = 3;
+  // Server ID. This must be unique among different server instances,
+  // but the same across all RPC's made to a particular server instance.
+  string server_id = 4;
 }
 
 message SimpleContext {

interop-testing/src/test/java/io/grpc/testing/integration/TestCasesTest.java

@@ -72,7 +72,8 @@ public void testCaseNamesShouldMapToEnums() {
     String[] additionalTestCases = {
       "client_compressed_unary_noprobe",
       "client_compressed_streaming_noprobe",
-      "very_large_request"
+      "very_large_request",
+      "pick_first_unary"
     };
 
     assertEquals(testCases.length + additionalTestCases.length, TestCases.values().length);