diff --git a/android/makevars.go b/android/makevars.go
index 20db65a..7d8864a 100644
--- a/android/makevars.go
+++ b/android/makevars.go
@@ -142,15 +142,19 @@
 
 var singletonMakeVarsProvidersKey = NewOnceKey("singletonMakeVarsProvidersKey")
 
+func getSingletonMakevarsProviders(config Config) *[]makeVarsProvider {
+	return config.Once(singletonMakeVarsProvidersKey, func() interface{} {
+		return &[]makeVarsProvider{}
+	}).(*[]makeVarsProvider)
+}
+
 // registerSingletonMakeVarsProvider adds a singleton that implements SingletonMakeVarsProvider to
 // the list of MakeVarsProviders to run.
 func registerSingletonMakeVarsProvider(config Config, singleton SingletonMakeVarsProvider) {
 	// Singletons are registered on the Context and may be different between different Contexts,
 	// for example when running multiple tests.  Store the SingletonMakeVarsProviders in the
 	// Config so they are attached to the Context.
-	singletonMakeVarsProviders := config.Once(singletonMakeVarsProvidersKey, func() interface{} {
-		return &[]makeVarsProvider{}
-	}).(*[]makeVarsProvider)
+	singletonMakeVarsProviders := getSingletonMakevarsProviders(config)
 
 	*singletonMakeVarsProviders = append(*singletonMakeVarsProviders,
 		makeVarsProvider{pctx, singletonMakeVarsProviderAdapter(singleton)})
@@ -175,7 +179,9 @@
 	return &makeVarsSingleton{}
 }
 
-type makeVarsSingleton struct{}
+type makeVarsSingleton struct {
+	installsForTesting []byte
+}
 
 type makeVarsProvider struct {
 	pctx PackageContext
@@ -238,7 +244,7 @@
 	var katiSymlinks []katiInstall
 
 	providers := append([]makeVarsProvider(nil), makeVarsInitProviders...)
-	providers = append(providers, *ctx.Config().Get(singletonMakeVarsProvidersKey).(*[]makeVarsProvider)...)
+	providers = append(providers, *getSingletonMakevarsProviders(ctx.Config())...)
 
 	for _, provider := range providers {
 		mctx := &makeVarsContext{
@@ -313,6 +319,8 @@
 	if err := pathtools.WriteFileIfChanged(installsFile, installsBytes, 0666); err != nil {
 		ctx.Errorf(err.Error())
 	}
+
+	s.installsForTesting = installsBytes
 }
 
 func (s *makeVarsSingleton) writeVars(vars []makeVarsVariable) []byte {