diff --git a/javatests/google/registry/batch/DeleteProberDataActionTest.java b/javatests/google/registry/batch/DeleteProberDataActionTest.java
index e27faf3e4..1b5dcf986 100644
--- a/javatests/google/registry/batch/DeleteProberDataActionTest.java
+++ b/javatests/google/registry/batch/DeleteProberDataActionTest.java
@@ -23,10 +23,8 @@ import static google.registry.testing.DatastoreHelper.persistResource;
 import static google.registry.testing.DatastoreHelper.persistSimpleResource;
 import static google.registry.util.DateTimeUtils.START_OF_TIME;
 
-import com.google.common.base.Optional;
 import com.google.common.collect.ImmutableSet;
 import com.googlecode.objectify.Key;
-import google.registry.mapreduce.MapreduceRunner;
 import google.registry.model.ImmutableObject;
 import google.registry.model.billing.BillingEvent;
 import google.registry.model.billing.BillingEvent.Reason;
@@ -74,7 +72,7 @@ public class DeleteProberDataActionTest extends MapreduceTestCase<DeleteProberDa
     persistResource(Registry.get("oa-canary.test").asBuilder().setTldType(TldType.TEST).build());
 
     action = new DeleteProberDataAction();
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>of(5), Optional.<Integer>absent());
+    action.mrRunner = makeDefaultRunner();
     action.response = new FakeResponse();
     action.isDryRun = false;
   }
diff --git a/javatests/google/registry/batch/ExpandRecurringBillingEventsActionTest.java b/javatests/google/registry/batch/ExpandRecurringBillingEventsActionTest.java
index db89d2d28..24d3f0678 100644
--- a/javatests/google/registry/batch/ExpandRecurringBillingEventsActionTest.java
+++ b/javatests/google/registry/batch/ExpandRecurringBillingEventsActionTest.java
@@ -32,7 +32,6 @@ import com.google.common.collect.ImmutableSortedMap;
 import com.google.common.collect.Iterables;
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.VoidWork;
-import google.registry.mapreduce.MapreduceRunner;
 import google.registry.model.billing.BillingEvent;
 import google.registry.model.billing.BillingEvent.Flag;
 import google.registry.model.billing.BillingEvent.Reason;
@@ -71,7 +70,7 @@ public class ExpandRecurringBillingEventsActionTest
   @Before
   public void init() {
     action = new ExpandRecurringBillingEventsAction();
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>of(5), Optional.<Integer>absent());
+    action.mrRunner = makeDefaultRunner();
     action.clock = clock;
     action.cursorTimeParam = Optional.absent();
     createTld("tld");
diff --git a/javatests/google/registry/export/ExportDomainListsActionTest.java b/javatests/google/registry/export/ExportDomainListsActionTest.java
index 97e9cd170..14720650a 100644
--- a/javatests/google/registry/export/ExportDomainListsActionTest.java
+++ b/javatests/google/registry/export/ExportDomainListsActionTest.java
@@ -28,9 +28,7 @@ import com.google.appengine.tools.cloudstorage.GcsFilename;
 import com.google.appengine.tools.cloudstorage.GcsService;
 import com.google.appengine.tools.cloudstorage.ListOptions;
 import com.google.appengine.tools.cloudstorage.ListResult;
-import com.google.common.base.Optional;
 import com.google.common.base.Splitter;
-import google.registry.mapreduce.MapreduceRunner;
 import google.registry.model.registry.Registry;
 import google.registry.model.registry.Registry.TldType;
 import google.registry.testing.ExceptionRule;
@@ -60,7 +58,7 @@ public class ExportDomainListsActionTest extends MapreduceTestCase<ExportDomainL
     persistResource(Registry.get("testtld").asBuilder().setTldType(TldType.TEST).build());
 
     action = new ExportDomainListsAction();
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>absent(), Optional.<Integer>absent());
+    action.mrRunner = makeDefaultRunner();
     action.response = new FakeResponse();
     action.gcsBucket = "outputbucket";
     action.gcsBufferSize = 500;
diff --git a/javatests/google/registry/flows/async/DeleteContactsAndHostsActionTest.java b/javatests/google/registry/flows/async/DeleteContactsAndHostsActionTest.java
index 6441d8966..7b6be957b 100644
--- a/javatests/google/registry/flows/async/DeleteContactsAndHostsActionTest.java
+++ b/javatests/google/registry/flows/async/DeleteContactsAndHostsActionTest.java
@@ -55,13 +55,11 @@ import static org.joda.time.Duration.standardSeconds;
 import com.google.appengine.api.taskqueue.QueueFactory;
 import com.google.appengine.api.taskqueue.TaskOptions;
 import com.google.appengine.api.taskqueue.TaskOptions.Method;
-import com.google.common.base.Optional;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.googlecode.objectify.Key;
-import google.registry.mapreduce.MapreduceRunner;
 import google.registry.model.EppResource;
 import google.registry.model.contact.ContactAddress;
 import google.registry.model.contact.ContactPhoneNumber;
@@ -133,7 +131,7 @@ public class DeleteContactsAndHostsActionTest
 
     action = new DeleteContactsAndHostsAction();
     action.clock = clock;
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>of(5), Optional.<Integer>of(2));
+    action.mrRunner = makeDefaultRunner();
     action.response = new FakeResponse();
     action.retrier = new Retrier(new FakeSleeper(clock), 1);
     action.queue = getQueue(QUEUE_ASYNC_DELETE);
diff --git a/javatests/google/registry/flows/async/DnsRefreshForHostRenameActionTest.java b/javatests/google/registry/flows/async/DnsRefreshForHostRenameActionTest.java
index 430447fbf..be03b203d 100644
--- a/javatests/google/registry/flows/async/DnsRefreshForHostRenameActionTest.java
+++ b/javatests/google/registry/flows/async/DnsRefreshForHostRenameActionTest.java
@@ -26,11 +26,9 @@ import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
 import static org.mockito.Mockito.verifyZeroInteractions;
 
-import com.google.common.base.Optional;
 import com.google.common.collect.ImmutableSet;
 import com.googlecode.objectify.Key;
 import google.registry.dns.DnsQueue;
-import google.registry.mapreduce.MapreduceRunner;
 import google.registry.model.host.HostResource;
 import google.registry.request.HttpException.BadRequestException;
 import google.registry.testing.ExceptionRule;
@@ -64,7 +62,7 @@ public class DnsRefreshForHostRenameActionTest
   private void runMapreduce(String hostKeyString) throws Exception {
     action = new DnsRefreshForHostRenameAction();
     action.hostKeyString = hostKeyString;
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>of(5), Optional.<Integer>absent());
+    action.mrRunner = makeDefaultRunner();
     action.response = new FakeResponse();
     action.run();
     executeTasksUntilEmpty("mapreduce");
diff --git a/javatests/google/registry/flows/async/RefreshDnsOnHostRenameActionTest.java b/javatests/google/registry/flows/async/RefreshDnsOnHostRenameActionTest.java
index 14e03ec5f..0b40badb6 100644
--- a/javatests/google/registry/flows/async/RefreshDnsOnHostRenameActionTest.java
+++ b/javatests/google/registry/flows/async/RefreshDnsOnHostRenameActionTest.java
@@ -33,10 +33,8 @@ import static org.joda.time.Duration.millis;
 import static org.joda.time.Duration.standardHours;
 import static org.joda.time.Duration.standardSeconds;
 
-import com.google.common.base.Optional;
 import com.google.common.collect.ImmutableSet;
 import com.googlecode.objectify.Key;
-import google.registry.mapreduce.MapreduceRunner;
 import google.registry.model.host.HostResource;
 import google.registry.testing.ExceptionRule;
 import google.registry.testing.FakeClock;
@@ -79,7 +77,7 @@ public class RefreshDnsOnHostRenameActionTest
 
     action = new RefreshDnsOnHostRenameAction();
     action.clock = clock;
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>of(5), Optional.<Integer>absent());
+    action.mrRunner = makeDefaultRunner();
     action.pullQueue = getQueue(QUEUE_ASYNC_HOST_RENAME);
     action.response = new FakeResponse();
     action.retrier = new Retrier(new FakeSleeper(clock), 1);
diff --git a/javatests/google/registry/rde/RdeContactImportActionTest.java b/javatests/google/registry/rde/RdeContactImportActionTest.java
index d6577247d..d9d27f8ad 100644
--- a/javatests/google/registry/rde/RdeContactImportActionTest.java
+++ b/javatests/google/registry/rde/RdeContactImportActionTest.java
@@ -58,7 +58,7 @@ public class RdeContactImportActionTest extends MapreduceTestCase<RdeContactImpo
   @Before
   public void before() throws Exception {
     response = new FakeResponse();
-    mrRunner = new MapreduceRunner(Optional.<Integer>absent(), Optional.<Integer>absent());
+    mrRunner = makeDefaultRunner();
     action = new RdeContactImportAction(
         mrRunner,
         response,
diff --git a/javatests/google/registry/rde/RdeStagingActionTest.java b/javatests/google/registry/rde/RdeStagingActionTest.java
index 3f0b5fffb..953f10994 100644
--- a/javatests/google/registry/rde/RdeStagingActionTest.java
+++ b/javatests/google/registry/rde/RdeStagingActionTest.java
@@ -36,14 +36,12 @@ import static java.util.Arrays.asList;
 import com.google.appengine.tools.cloudstorage.GcsFilename;
 import com.google.appengine.tools.cloudstorage.GcsService;
 import com.google.appengine.tools.cloudstorage.GcsServiceFactory;
-import com.google.common.base.Optional;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.net.InetAddresses;
 import com.googlecode.objectify.VoidWork;
 import google.registry.keyring.api.Keyring;
 import google.registry.keyring.api.PgpHelper;
-import google.registry.mapreduce.MapreduceRunner;
 import google.registry.model.common.Cursor;
 import google.registry.model.common.Cursor.CursorType;
 import google.registry.model.host.HostResource;
@@ -123,7 +121,7 @@ public class RdeStagingActionTest extends MapreduceTestCase<RdeStagingAction> {
     inject.setStaticField(Ofy.class, "clock", clock);
     action = new RdeStagingAction();
     action.clock = clock;
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>absent(), Optional.<Integer>absent());
+    action.mrRunner = makeDefaultRunner();
     action.reducer = new RdeStagingReducer();
     action.reducer.ghostrydeBufferSize = 31337;
     action.reducer.lockTimeout = Duration.standardHours(1);
diff --git a/javatests/google/registry/testing/mapreduce/BUILD b/javatests/google/registry/testing/mapreduce/BUILD
index 330ee3e44..799edcaff 100644
--- a/javatests/google/registry/testing/mapreduce/BUILD
+++ b/javatests/google/registry/testing/mapreduce/BUILD
@@ -26,6 +26,8 @@ java_library(
         "//third_party/java/mockito",
         "//third_party/java/servlet/servlet_api",
         "//third_party/java/truth",
+        "//java/google/registry/config",
+        "//java/google/registry/mapreduce",
         "//java/google/registry/model",
         "//java/google/registry/util",
         "//javatests/google/registry/testing",
diff --git a/javatests/google/registry/testing/mapreduce/MapreduceTestCase.java b/javatests/google/registry/testing/mapreduce/MapreduceTestCase.java
index a17bd90f6..d6a198cad 100644
--- a/javatests/google/registry/testing/mapreduce/MapreduceTestCase.java
+++ b/javatests/google/registry/testing/mapreduce/MapreduceTestCase.java
@@ -32,6 +32,9 @@ import com.google.appengine.tools.pipeline.impl.servlets.PipelineServlet;
 import com.google.appengine.tools.pipeline.impl.servlets.TaskHandler;
 import com.google.apphosting.api.ApiProxy;
 import com.google.common.base.CharMatcher;
+import com.google.common.base.Optional;
+import google.registry.config.RegistryEnvironment;
+import google.registry.mapreduce.MapreduceRunner;
 import google.registry.testing.AppEngineRule;
 import google.registry.testing.FakeClock;
 import google.registry.testing.ShardableTestCase;
@@ -84,6 +87,11 @@ public abstract class MapreduceTestCase<T> extends ShardableTestCase {
     proxy.setProperty(LocalBlobstoreService.NO_STORAGE_PROPERTY, "true");
   }
 
+  protected MapreduceRunner makeDefaultRunner() {
+    int numBuckets = RegistryEnvironment.get().config().getEppResourceIndexBucketCount();
+    return new MapreduceRunner(Optional.<Integer>of(numBuckets), Optional.<Integer>of(1));
+  }
+
   protected List<QueueStateInfo.TaskStateInfo> getTasks(String queueName) {
     return taskQueue.getQueueStateInfo().get(queueName).getTaskInfo();
   }
diff --git a/javatests/google/registry/tools/server/GenerateZoneFilesActionTest.java b/javatests/google/registry/tools/server/GenerateZoneFilesActionTest.java
index e9e4b09a0..daadbee36 100644
--- a/javatests/google/registry/tools/server/GenerateZoneFilesActionTest.java
+++ b/javatests/google/registry/tools/server/GenerateZoneFilesActionTest.java
@@ -31,13 +31,11 @@ import static org.joda.time.Duration.standardDays;
 
 import com.google.appengine.tools.cloudstorage.GcsFilename;
 import com.google.appengine.tools.cloudstorage.GcsService;
-import com.google.common.base.Optional;
 import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.googlecode.objectify.Key;
-import google.registry.mapreduce.MapreduceRunner;
 import google.registry.model.domain.secdns.DelegationSignerData;
 import google.registry.model.host.HostResource;
 import google.registry.testing.FakeClock;
@@ -97,7 +95,7 @@ public class GenerateZoneFilesActionTest extends MapreduceTestCase<GenerateZoneF
         .build());
 
     GenerateZoneFilesAction action = new GenerateZoneFilesAction();
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>absent(), Optional.<Integer>absent());
+    action.mrRunner = makeDefaultRunner();
     action.bucket = "zonefiles-bucket";
     action.gcsBufferSize = 123;
     action.datastoreRetention = standardDays(29);
diff --git a/javatests/google/registry/tools/server/KillAllCommitLogsActionTest.java b/javatests/google/registry/tools/server/KillAllCommitLogsActionTest.java
index 471e79f8f..10e03bf6d 100644
--- a/javatests/google/registry/tools/server/KillAllCommitLogsActionTest.java
+++ b/javatests/google/registry/tools/server/KillAllCommitLogsActionTest.java
@@ -27,12 +27,10 @@ import static google.registry.util.DateTimeUtils.START_OF_TIME;
 import static java.util.Arrays.asList;
 
 import com.google.appengine.api.datastore.Entity;
-import com.google.common.base.Optional;
 import com.google.common.base.Predicate;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
-import google.registry.mapreduce.MapreduceRunner;
 import google.registry.model.ImmutableObject;
 import google.registry.model.ofy.CommitLogBucket;
 import google.registry.model.ofy.CommitLogCheckpoint;
@@ -59,7 +57,7 @@ public class KillAllCommitLogsActionTest extends MapreduceTestCase<KillAllCommit
 
   private void runMapreduce() throws Exception {
     action = new KillAllCommitLogsAction();
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>absent(), Optional.<Integer>absent());
+    action.mrRunner = makeDefaultRunner();
     action.response = new FakeResponse();
     action.run();
     executeTasksUntilEmpty("mapreduce");
diff --git a/javatests/google/registry/tools/server/KillAllEppResourcesActionTest.java b/javatests/google/registry/tools/server/KillAllEppResourcesActionTest.java
index 770640eff..7e6b5261a 100644
--- a/javatests/google/registry/tools/server/KillAllEppResourcesActionTest.java
+++ b/javatests/google/registry/tools/server/KillAllEppResourcesActionTest.java
@@ -32,12 +32,10 @@ import static google.registry.util.DateTimeUtils.START_OF_TIME;
 import static java.util.Arrays.asList;
 
 import com.google.appengine.api.datastore.Entity;
-import com.google.common.base.Optional;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.Iterables;
 import com.googlecode.objectify.Key;
-import google.registry.mapreduce.MapreduceRunner;
 import google.registry.model.EppResource;
 import google.registry.model.ImmutableObject;
 import google.registry.model.billing.BillingEvent;
@@ -84,7 +82,7 @@ public class KillAllEppResourcesActionTest extends MapreduceTestCase<KillAllEppR
 
   private void runMapreduce() throws Exception {
     action = new KillAllEppResourcesAction();
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>absent(), Optional.<Integer>absent());
+    action.mrRunner = makeDefaultRunner();
     action.response = new FakeResponse();
     action.run();
     executeTasksUntilEmpty("mapreduce");
diff --git a/javatests/google/registry/tools/server/ResaveAllEppResourcesActionTest.java b/javatests/google/registry/tools/server/ResaveAllEppResourcesActionTest.java
index e3de78f07..2cf93d3bd 100644
--- a/javatests/google/registry/tools/server/ResaveAllEppResourcesActionTest.java
+++ b/javatests/google/registry/tools/server/ResaveAllEppResourcesActionTest.java
@@ -18,8 +18,6 @@ import static com.google.common.truth.Truth.assertThat;
 import static google.registry.model.ofy.ObjectifyService.ofy;
 import static google.registry.testing.DatastoreHelper.persistActiveContact;
 
-import com.google.common.base.Optional;
-import google.registry.mapreduce.MapreduceRunner;
 import google.registry.model.contact.ContactResource;
 import google.registry.testing.FakeResponse;
 import google.registry.testing.mapreduce.MapreduceTestCase;
@@ -37,7 +35,7 @@ public class ResaveAllEppResourcesActionTest
   @Before
   public void init() {
     action = new ResaveAllEppResourcesAction();
-    action.mrRunner = new MapreduceRunner(Optional.<Integer>of(5), Optional.<Integer>absent());
+    action.mrRunner = makeDefaultRunner();
     action.response = new FakeResponse();
   }