Add MemcacheHelper to simplify memcache usage in tests

And make two callsites use it.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=154189438

javatests/google/registry/flows/domain/DomainApplicationInfoFlowTest.java

@@ -14,7 +14,6 @@
 
 package google.registry.flows.domain;
 
-import static com.google.appengine.tools.development.testing.LocalMemcacheServiceTestConfig.getLocalMemcacheService;
 import static com.google.common.base.Predicates.equalTo;
 import static com.google.common.io.BaseEncoding.base16;
 import static com.google.common.truth.Truth.assertThat;
@@ -24,11 +23,10 @@ import static google.registry.testing.DatastoreHelper.createTld;
 import static google.registry.testing.DatastoreHelper.persistActiveContact;
 import static google.registry.testing.DatastoreHelper.persistActiveHost;
 import static google.registry.testing.DatastoreHelper.persistResource;
+import static google.registry.testing.MemcacheHelper.clearMemcache;
 import static google.registry.testing.TestDataHelper.loadFileWithSubstitutions;
 import static google.registry.util.DatastoreServiceUtils.KEY_TO_KIND_FUNCTION;
 
-import com.google.appengine.api.memcache.MemcacheServicePb.MemcacheFlushRequest;
-import com.google.appengine.tools.development.LocalRpcService;
 import com.google.common.base.Predicate;
 import com.google.common.base.Predicates;
 import com.google.common.collect.FluentIterable;
@@ -336,8 +334,7 @@ public class DomainApplicationInfoFlowTest
     persistTestEntities(HostsState.HOSTS_EXIST, MarksState.NO_MARKS_EXIST);
     // Clear out memcache and session cache so that we count actual Datastore calls.
     ofy().clearSessionCache();
-    getLocalMemcacheService().flushAll(
+    clearMemcache();
-        new LocalRpcService.Status(), MemcacheFlushRequest.newBuilder().build());
     int numPreviousReads = RequestCapturingAsyncDatastoreService.getReads().size();
     doSuccessfulTest("domain_info_sunrise_response.xml", HostsState.HOSTS_EXIST);
     // Get all of the keys loaded in the flow, with each distinct load() call as a list of keys.

javatests/google/registry/flows/domain/DomainInfoFlowTest.java

@@ -14,7 +14,6 @@
 
 package google.registry.flows.domain;
 
-import static com.google.appengine.tools.development.testing.LocalMemcacheServiceTestConfig.getLocalMemcacheService;
 import static com.google.common.base.Predicates.equalTo;
 import static com.google.common.io.BaseEncoding.base16;
 import static com.google.common.truth.Truth.assertThat;
@@ -25,11 +24,10 @@ import static google.registry.testing.DatastoreHelper.newDomainResource;
 import static google.registry.testing.DatastoreHelper.persistActiveContact;
 import static google.registry.testing.DatastoreHelper.persistActiveHost;
 import static google.registry.testing.DatastoreHelper.persistResource;
+import static google.registry.testing.MemcacheHelper.clearMemcache;
 import static google.registry.testing.TestDataHelper.loadFileWithSubstitutions;
 import static google.registry.util.DatastoreServiceUtils.KEY_TO_KIND_FUNCTION;
 
-import com.google.appengine.api.memcache.MemcacheServicePb.MemcacheFlushRequest;
-import com.google.appengine.tools.development.LocalRpcService;
 import com.google.common.base.Predicate;
 import com.google.common.base.Predicates;
 import com.google.common.collect.FluentIterable;
@@ -641,8 +639,7 @@ public class DomainInfoFlowTest extends ResourceFlowTestCase<DomainInfoFlow, Dom
     persistTestEntities(false);
     // Clear out memcache and session cache so that we count actual Datastore calls.
     ofy().clearSessionCache();
-    getLocalMemcacheService().flushAll(
+    clearMemcache();
-        new LocalRpcService.Status(), MemcacheFlushRequest.newBuilder().build());
     int numPreviousReads = RequestCapturingAsyncDatastoreService.getReads().size();
     doSuccessfulTest("domain_info_response.xml", false);
     // Get all of the keys loaded in the flow, with each distinct load() call as a list of keys.

javatests/google/registry/testing/MemcacheHelper.java

@@ -0,0 +1,45 @@
+// Copyright 2017 The Nomulus Authors. All Rights Reserved.
+//
+// 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
+//
+//     http://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 google.registry.testing;
+
+import static com.google.appengine.tools.development.testing.LocalMemcacheServiceTestConfig.getLocalMemcacheService;
+import static google.registry.model.ofy.ObjectifyService.ofy;
+
+import com.google.appengine.api.memcache.MemcacheServicePb.MemcacheFlushRequest;
+import com.google.appengine.tools.development.LocalRpcService;
+import com.googlecode.objectify.Key;
+
+/** Utilities for manipulating memcache in tests. */
+public class MemcacheHelper {
+
+  /** Clear out memcache */
+  public static void clearMemcache() {
+    getLocalMemcacheService().flushAll(
+        new LocalRpcService.Status(), MemcacheFlushRequest.newBuilder().build());
+  }
+
+  /** Clears memcache, inserts the specific keys requested, and clears the session cache. */
+  public static void setMemcacheContents(Key<?>... keys) {
+    // Clear out the session cache. This is needed so that the calls to loadWithMemcache() below
+    // actually go to datastore and write to memcache instead of bottoming out at the session cache.
+    ofy().clearSessionCache();
+    clearMemcache();
+    // Load the entities we want to be in memcache. If an entity's type is not marked with @Cache it
+    // will be ignored.
+    ofy().loadWithMemcache().keys(keys).values();
+    // Clear out the session cache again, since it now contains the newly loaded types.
+    ofy().clearSessionCache();
+  }
+}