Add container property to aconfig_declarations.

Bug: 311155208
Test: Unit test
Change-Id: I7b187138856d0144203961e82b6dad5e2f8eed9d

aconfig/codegen/testing.go

@@ -0,0 +1,25 @@
+// Copyright (C) 2021 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 codegen
+
+import (
+	"android/soong/aconfig"
+	"android/soong/android"
+)
+
+var PrepareForTestWithAconfigBuildComponents = android.FixtureRegisterWithContext(func(ctx android.RegistrationContext) {
+	ctx.RegisterModuleType("aconfig_declarations", aconfig.DeclarationsFactory)
+	RegisterBuildComponents(ctx)
+})