fix(bigtable): Fix empty RowResult semantics in TestProxy.

java-bigtable/test-proxy/src/main/java/com/google/cloud/bigtable/testproxy/CbtTestProxy.java

@@ -48,6 +48,7 @@
 import com.google.cloud.bigtable.data.v2.models.sql.SqlType;
 import com.google.cloud.bigtable.data.v2.stub.EnhancedBigtableStubSettings;
 import com.google.cloud.bigtable.testproxy.CloudBigtableV2TestProxyGrpc.CloudBigtableV2TestProxyImplBase;
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import com.google.protobuf.ByteString;
 import com.google.protobuf.util.Durations;
@@ -395,6 +396,9 @@ public void readRow(ReadRowRequest request, StreamObserver<RowResult> responseOb
             resultBuilder.setStatus(com.google.rpc.Status.getDefaultInstance()).build());
       } else {
         logger.info(String.format("readRow() did not find row: %s", request.getRowKey()));
+        responseObserver.onNext(
+            // Note that the default instance == OK
+            RowResult.newBuilder().setStatus(com.google.rpc.Status.getDefaultInstance()).build());
       }
     } catch (ApiException e) {
       responseObserver.onNext(RowResult.newBuilder().setStatus(convertStatus(e)).build());
@@ -640,6 +644,9 @@ public void readModifyWriteRow(
         logger.info(
             String.format(
                 "readModifyWriteRow() did not find row: %s", request.getRequest().getRowKey()));
+        responseObserver.onNext(
+            // Note that the default instance == OK
+            RowResult.newBuilder().setStatus(com.google.rpc.Status.getDefaultInstance()).build());
       }
     } catch (ApiException e) {
       responseObserver.onNext(RowResult.newBuilder().setStatus(convertStatus(e)).build());
@@ -815,7 +822,7 @@ private CredentialsProvider getCredentialsProvider(String accessToken) {
         OAuth2Credentials.create(new AccessToken(accessToken, null)));
   }
 
-  private final ConcurrentHashMap<String, CbtClient> idClientMap;
+  @VisibleForTesting final ConcurrentHashMap<String, CbtClient> idClientMap;
 
   private static final Pattern tablePattern =
       Pattern.compile("projects/([^/]+)/instances/([^/]+)/tables/([^/]+)");

java-bigtable/test-proxy/src/test/java/com/google/cloud/bigtable/testproxy/CbtTestProxyTest.java

@@ -0,0 +1,156 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.cloud.bigtable.testproxy;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import com.google.bigtable.v2.ReadModifyWriteRule;
+import com.google.cloud.bigtable.data.v2.BigtableDataClient;
+import com.google.cloud.bigtable.data.v2.BigtableDataSettings;
+import com.google.cloud.bigtable.data.v2.models.Filters.Filter;
+import com.google.cloud.bigtable.data.v2.models.ReadModifyWriteRow;
+import com.google.cloud.bigtable.data.v2.models.Row;
+import com.google.cloud.bigtable.data.v2.models.RowCell;
+import com.google.cloud.bigtable.testproxy.CbtTestProxy.CbtClient;
+import com.google.common.collect.ImmutableList;
+import com.google.protobuf.ByteString;
+import com.google.rpc.Code;
+import io.grpc.stub.StreamObserver;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.mockito.ArgumentCaptor;
+
+@RunWith(JUnit4.class)
+public class CbtTestProxyTest {
+
+  private static final String CLIENT_ID = "test-client";
+  private static final String TABLE_NAME =
+      "projects/my-project/instances/my-instance/tables/my-table";
+  private static final String TABLE_ID = "my-table";
+
+  private BigtableDataClient mockDataClient;
+  private CbtTestProxy proxy;
+
+  @Before
+  public void setUp() {
+    mockDataClient = mock(BigtableDataClient.class);
+    BigtableDataSettings settings =
+        BigtableDataSettings.newBuilderForEmulator(8080)
+            .setProjectId("my-project")
+            .setInstanceId("my-instance")
+            .build();
+    proxy = CbtTestProxy.create();
+    proxy.idClientMap.put(CLIENT_ID, CbtClient.create(settings, mockDataClient));
+  }
+
+  @Test
+  public void testReadRowNotFoundEmitsEmptyRowResultWithOkStatus() {
+    when(mockDataClient.readRow(eq(TABLE_ID), eq("missing-row"), any(Filter.class)))
+        .thenReturn(null);
+
+    @SuppressWarnings("unchecked")
+    StreamObserver<RowResult> responseObserver = mock(StreamObserver.class);
+    ReadRowRequest request =
+        ReadRowRequest.newBuilder()
+            .setClientId(CLIENT_ID)
+            .setTableName(TABLE_NAME)
+            .setRowKey("missing-row")
+            .build();
+
+    proxy.readRow(request, responseObserver);
+
+    ArgumentCaptor<RowResult> resultCaptor = ArgumentCaptor.forClass(RowResult.class);
+    verify(responseObserver).onNext(resultCaptor.capture());
+    verify(responseObserver).onCompleted();
+
+    RowResult result = resultCaptor.getValue();
+    assertThat(result.getStatus().getCode()).isEqualTo(Code.OK.getNumber());
+    assertThat(result.hasRow()).isFalse();
+  }
+
+  @Test
+  public void testReadRowFoundEmitsPopulatedRowResultWithOkStatus() {
+    Row row =
+        Row.create(
+            ByteString.copyFromUtf8("row-1"),
+            ImmutableList.of(
+                RowCell.create(
+                    "cf",
+                    ByteString.copyFromUtf8("col"),
+                    1000L,
+                    ImmutableList.of(),
+                    ByteString.copyFromUtf8("val"))));
+    when(mockDataClient.readRow(eq(TABLE_ID), eq("row-1"), any(Filter.class))).thenReturn(row);
+
+    @SuppressWarnings("unchecked")
+    StreamObserver<RowResult> responseObserver = mock(StreamObserver.class);
+    ReadRowRequest request =
+        ReadRowRequest.newBuilder()
+            .setClientId(CLIENT_ID)
+            .setTableName(TABLE_NAME)
+            .setRowKey("row-1")
+            .build();
+
+    proxy.readRow(request, responseObserver);
+
+    ArgumentCaptor<RowResult> resultCaptor = ArgumentCaptor.forClass(RowResult.class);
+    verify(responseObserver).onNext(resultCaptor.capture());
+    verify(responseObserver).onCompleted();
+
+    RowResult result = resultCaptor.getValue();
+    assertThat(result.getStatus().getCode()).isEqualTo(Code.OK.getNumber());
+    assertThat(result.hasRow()).isTrue();
+    assertThat(result.getRow().getKey()).isEqualTo(ByteString.copyFromUtf8("row-1"));
+  }
+
+  @Test
+  public void testReadModifyWriteRowNullEmitsEmptyRowResultWithOkStatus() {
+    when(mockDataClient.readModifyWriteRow(any(ReadModifyWriteRow.class))).thenReturn(null);
+
+    @SuppressWarnings("unchecked")
+    StreamObserver<RowResult> responseObserver = mock(StreamObserver.class);
+    ReadModifyWriteRowRequest request =
+        ReadModifyWriteRowRequest.newBuilder()
+            .setClientId(CLIENT_ID)
+            .setRequest(
+                com.google.bigtable.v2.ReadModifyWriteRowRequest.newBuilder()
+                    .setTableName(TABLE_NAME)
+                    .setRowKey(ByteString.copyFromUtf8("rmw-row"))
+                    .addRules(
+                        ReadModifyWriteRule.newBuilder()
+                            .setFamilyName("cf")
+                            .setColumnQualifier(ByteString.copyFromUtf8("col"))
+                            .setAppendValue(ByteString.copyFromUtf8("v"))))
+            .build();
+
+    proxy.readModifyWriteRow(request, responseObserver);
+
+    ArgumentCaptor<RowResult> resultCaptor = ArgumentCaptor.forClass(RowResult.class);
+    verify(responseObserver).onNext(resultCaptor.capture());
+    verify(responseObserver).onCompleted();
+
+    RowResult result = resultCaptor.getValue();
+    assertThat(result.getStatus().getCode()).isEqualTo(Code.OK.getNumber());
+    assertThat(result.hasRow()).isFalse();
+  }
+}