Add test for NPE in account index query

This is a test for regression caused by: I3c4616d08e. As the consequence
index collection instances were not correctly propagated into plugin's
Guice injectors.

Bug: Issue 8398
Change-Id: I3f99fecec49c72e9d565f6b5e55b7fd73bf62bdc
diff --git a/BUILD b/BUILD
index d6d4eeb..9ccdae9 100644
--- a/BUILD
+++ b/BUILD
@@ -1,4 +1,5 @@
-load("//tools/bzl:plugin.bzl", "gerrit_plugin")
+load("//tools/bzl:junit.bzl", "junit_tests")
+load("//tools/bzl:plugin.bzl", "gerrit_plugin", "PLUGIN_DEPS", "PLUGIN_TEST_DEPS")
 
 gerrit_plugin(
     name = "singleusergroup",
@@ -9,3 +10,13 @@
     ],
     resources = glob(["src/main/resources/**/*"]),
 )
+
+junit_tests(
+    name = "singleusergroup_tests",
+    srcs = glob(["src/test/java/**/*Test.java"]),
+    tags = ["replication"],
+    visibility = ["//visibility:public"],
+    deps = PLUGIN_TEST_DEPS + PLUGIN_DEPS + [
+        ":singleusergroup__plugin",
+    ],
+)
diff --git a/src/test/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroupTest.java b/src/test/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroupTest.java
new file mode 100644
index 0000000..d403cc4
--- /dev/null
+++ b/src/test/java/com/googlesource/gerrit/plugins/singleusergroup/SingleUserGroupTest.java
@@ -0,0 +1,39 @@
+// Copyright (C) 2018 The Android Open Source Project
+//
+// 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 com.googlesource.gerrit.plugins.singleusergroup;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.gerrit.acceptance.LightweightPluginDaemonTest;
+import com.google.gerrit.acceptance.NoHttpd;
+import com.google.gerrit.acceptance.TestPlugin;
+import com.google.gerrit.extensions.common.GroupInfo;
+import java.util.Map;
+import org.junit.Test;
+
+@NoHttpd
+@TestPlugin(
+  name = "singleusergroup",
+  sysModule = "com.googlesource.gerrit.plugins.singleusergroup.SingleUserGroup$Module"
+)
+public class SingleUserGroupTest extends LightweightPluginDaemonTest {
+  @Test
+  public void testSuggestion() throws Exception {
+    // No ability to modify account and therefore no ACL to see secondary email
+    setApiUser(user);
+    Map<String, GroupInfo> groups = gApi.groups().list().withSuggest("adm").getAsMap();
+    assertThat(groups).containsKey("user/Administrator (admin)");
+  }
+}