info: add additional information to error message

google-cloud-spanner/src/main/java/com/google/cloud/spanner/DatabaseAdminClientImpl.java

@@ -28,6 +28,7 @@
 import com.google.cloud.spanner.SpannerImpl.PageFetcher;
 import com.google.cloud.spanner.spi.v1.SpannerRpc;
 import com.google.cloud.spanner.spi.v1.SpannerRpc.Paginated;
+import com.google.common.base.MoreObjects;
 import com.google.common.base.Preconditions;
 import com.google.protobuf.Empty;
 import com.google.spanner.admin.database.v1.CreateDatabaseMetadata;
@@ -155,7 +156,18 @@ public Page<Database> listDatabases(String instanceId, ListOption... options) {
           @Override
           public Paginated<com.google.spanner.admin.database.v1.Database> getNextPage(
               String nextPageToken) {
-            return rpc.listDatabases(instanceName, pageSize, nextPageToken);
+            try {
+              return rpc.listDatabases(instanceName, pageSize, nextPageToken);
+            } catch (SpannerException e) {
+              throw SpannerExceptionFactory.newSpannerException(
+                  e.getErrorCode(),
+                  String.format(
+                      "Failed to list the databases of %s with pageToken %s: %s",
+                      instanceName,
+                      MoreObjects.firstNonNull(nextPageToken, "<null>"),
+                      e.getMessage()),
+                  e);
+            }
           }
 
           @Override

google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseAdminClientImplTest.java

@@ -43,6 +43,7 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -170,6 +171,39 @@ public void listDatabases() {
     assertThat(dbs.size()).isEqualTo(2);
   }
 
+  @Test
+  public void listDatabasesError() {
+    when(rpc.listDatabases(INSTANCE_NAME, 1, null))
+        .thenThrow(
+            SpannerExceptionFactory.newSpannerException(ErrorCode.INVALID_ARGUMENT, "Test error"));
+    try {
+      client.listDatabases(INSTANCE_ID, Options.pageSize(1));
+      Assert.fail("Missing expected exception");
+    } catch (SpannerException e) {
+      assertThat(e.getMessage()).contains(INSTANCE_NAME);
+      // Assert that the call was done without a page token.
+      assertThat(e.getMessage()).contains("with pageToken <null>");
+    }
+  }
+
+  @Test
+  public void listDatabaseErrorWithToken() {
+    String pageToken = "token";
+    when(rpc.listDatabases(INSTANCE_NAME, 1, null))
+        .thenReturn(new Paginated<>(ImmutableList.<Database>of(getDatabaseProto()), pageToken));
+    when(rpc.listDatabases(INSTANCE_NAME, 1, pageToken))
+        .thenThrow(
+            SpannerExceptionFactory.newSpannerException(ErrorCode.INVALID_ARGUMENT, "Test error"));
+    try {
+      Lists.newArrayList(client.listDatabases(INSTANCE_ID, Options.pageSize(1)).iterateAll());
+      Assert.fail("Missing expected exception");
+    } catch (SpannerException e) {
+      assertThat(e.getMessage()).contains(INSTANCE_NAME);
+      // Assert that the call was done without a page token.
+      assertThat(e.getMessage()).contains(String.format("with pageToken %s", pageToken));
+    }
+  }
+
   @Test
   public void getDatabaseIAMPolicy() {
     when(rpc.getDatabaseAdminIAMPolicy(DB_NAME))