diff --git a/android/filegroup.go b/android/filegroup.go
index fd4a2fe49..3d1bbc533 100644
--- a/android/filegroup.go
+++ b/android/filegroup.go
@@ -23,7 +23,7 @@ import (
 
 func init() {
 	RegisterModuleType("filegroup", FileGroupFactory)
-	RegisterBp2BuildMutator("filegroup", bp2buildMutator)
+	RegisterBp2BuildMutator("filegroup", FilegroupBp2Build)
 }
 
 // https://docs.bazel.build/versions/master/be/general.html#filegroup
@@ -51,7 +51,7 @@ func (bfg *bazelFilegroup) Name() string {
 func (bfg *bazelFilegroup) GenerateAndroidBuildActions(ctx ModuleContext) {}
 
 // TODO: Create helper functions to avoid this boilerplate.
-func bp2buildMutator(ctx TopDownMutatorContext) {
+func FilegroupBp2Build(ctx TopDownMutatorContext) {
 	if m, ok := ctx.Module().(*fileGroup); ok {
 		name := "__bp2build__" + m.base().BaseModuleName()
 		ctx.CreateModule(BazelFileGroupFactory, &bazelFilegroupAttributes{
diff --git a/android/testing.go b/android/testing.go
index 76172d18e..5640c2981 100644
--- a/android/testing.go
+++ b/android/testing.go
@@ -89,7 +89,7 @@ func (ctx *TestContext) RegisterBp2BuildMutator(moduleType string, m func(TopDow
 	f := func(ctx RegisterMutatorsContext) {
 		ctx.TopDown(mutatorName, m)
 	}
-	bp2buildMutators = append(bp2buildMutators, f)
+	ctx.bp2buildMutators = append(ctx.bp2buildMutators, f)
 }
 
 func (ctx *TestContext) Register() {
@@ -100,7 +100,7 @@ func (ctx *TestContext) Register() {
 
 // RegisterForBazelConversion prepares a test context for bp2build conversion.
 func (ctx *TestContext) RegisterForBazelConversion() {
-	RegisterMutatorsForBazelConversion(ctx.Context.Context, bp2buildMutators)
+	RegisterMutatorsForBazelConversion(ctx.Context.Context, ctx.bp2buildMutators)
 }
 
 func (ctx *TestContext) ParseFileList(rootDir string, filePaths []string) (deps []string, errs []error) {
diff --git a/bp2build/build_conversion_test.go b/bp2build/build_conversion_test.go
index 367e13f75..73ca92fa1 100644
--- a/bp2build/build_conversion_test.go
+++ b/bp2build/build_conversion_test.go
@@ -270,16 +270,18 @@ func TestGenerateBazelTargetModules(t *testing.T) {
 
 func TestModuleTypeBp2Build(t *testing.T) {
 	testCases := []struct {
-		moduleTypeUnderTest        string
-		moduleTypeUnderTestFactory android.ModuleFactory
-		bp                         string
-		expectedBazelTarget        string
-		description                string
+		moduleTypeUnderTest                string
+		moduleTypeUnderTestFactory         android.ModuleFactory
+		moduleTypeUnderTestBp2BuildMutator func(android.TopDownMutatorContext)
+		bp                                 string
+		expectedBazelTarget                string
+		description                        string
 	}{
 		{
-			description:                "filegroup with no srcs",
-			moduleTypeUnderTest:        "filegroup",
-			moduleTypeUnderTestFactory: android.FileGroupFactory,
+			description:                        "filegroup with no srcs",
+			moduleTypeUnderTest:                "filegroup",
+			moduleTypeUnderTestFactory:         android.FileGroupFactory,
+			moduleTypeUnderTestBp2BuildMutator: android.FilegroupBp2Build,
 			bp: `filegroup {
 	name: "foo",
 	srcs: [],
@@ -291,9 +293,10 @@ func TestModuleTypeBp2Build(t *testing.T) {
 )`,
 		},
 		{
-			description:                "filegroup with srcs",
-			moduleTypeUnderTest:        "filegroup",
-			moduleTypeUnderTestFactory: android.FileGroupFactory,
+			description:                        "filegroup with srcs",
+			moduleTypeUnderTest:                "filegroup",
+			moduleTypeUnderTestFactory:         android.FileGroupFactory,
+			moduleTypeUnderTestBp2BuildMutator: android.FilegroupBp2Build,
 			bp: `filegroup {
 	name: "foo",
 	srcs: ["a", "b"],
@@ -307,9 +310,10 @@ func TestModuleTypeBp2Build(t *testing.T) {
 )`,
 		},
 		{
-			description:                "genrule with command line variable replacements",
-			moduleTypeUnderTest:        "genrule",
-			moduleTypeUnderTestFactory: genrule.GenRuleFactory,
+			description:                        "genrule with command line variable replacements",
+			moduleTypeUnderTest:                "genrule",
+			moduleTypeUnderTestFactory:         genrule.GenRuleFactory,
+			moduleTypeUnderTestBp2BuildMutator: genrule.GenruleBp2Build,
 			bp: `genrule {
     name: "foo",
     out: ["foo.out"],
@@ -332,9 +336,10 @@ func TestModuleTypeBp2Build(t *testing.T) {
 )`,
 		},
 		{
-			description:                "genrule using $(locations :label)",
-			moduleTypeUnderTest:        "genrule",
-			moduleTypeUnderTestFactory: genrule.GenRuleFactory,
+			description:                        "genrule using $(locations :label)",
+			moduleTypeUnderTest:                "genrule",
+			moduleTypeUnderTestFactory:         genrule.GenRuleFactory,
+			moduleTypeUnderTestBp2BuildMutator: genrule.GenruleBp2Build,
 			bp: `genrule {
     name: "foo",
     out: ["foo.out"],
@@ -357,9 +362,10 @@ func TestModuleTypeBp2Build(t *testing.T) {
 )`,
 		},
 		{
-			description:                "genrule using $(location) label should substitute first tool label automatically",
-			moduleTypeUnderTest:        "genrule",
-			moduleTypeUnderTestFactory: genrule.GenRuleFactory,
+			description:                        "genrule using $(location) label should substitute first tool label automatically",
+			moduleTypeUnderTest:                "genrule",
+			moduleTypeUnderTestFactory:         genrule.GenRuleFactory,
+			moduleTypeUnderTestBp2BuildMutator: genrule.GenruleBp2Build,
 			bp: `genrule {
     name: "foo",
     out: ["foo.out"],
@@ -383,9 +389,10 @@ func TestModuleTypeBp2Build(t *testing.T) {
 )`,
 		},
 		{
-			description:                "genrule using $(locations) label should substitute first tool label automatically",
-			moduleTypeUnderTest:        "genrule",
-			moduleTypeUnderTestFactory: genrule.GenRuleFactory,
+			description:                        "genrule using $(locations) label should substitute first tool label automatically",
+			moduleTypeUnderTest:                "genrule",
+			moduleTypeUnderTestFactory:         genrule.GenRuleFactory,
+			moduleTypeUnderTestBp2BuildMutator: genrule.GenruleBp2Build,
 			bp: `genrule {
     name: "foo",
     out: ["foo.out"],
@@ -409,9 +416,10 @@ func TestModuleTypeBp2Build(t *testing.T) {
 )`,
 		},
 		{
-			description:                "genrule without tools or tool_files can convert successfully",
-			moduleTypeUnderTest:        "genrule",
-			moduleTypeUnderTestFactory: genrule.GenRuleFactory,
+			description:                        "genrule without tools or tool_files can convert successfully",
+			moduleTypeUnderTest:                "genrule",
+			moduleTypeUnderTestFactory:         genrule.GenRuleFactory,
+			moduleTypeUnderTestBp2BuildMutator: genrule.GenruleBp2Build,
 			bp: `genrule {
     name: "foo",
     out: ["foo.out"],
@@ -436,6 +444,7 @@ func TestModuleTypeBp2Build(t *testing.T) {
 		config := android.TestConfig(buildDir, nil, testCase.bp, nil)
 		ctx := android.NewTestContext(config)
 		ctx.RegisterModuleType(testCase.moduleTypeUnderTest, testCase.moduleTypeUnderTestFactory)
+		ctx.RegisterBp2BuildMutator(testCase.moduleTypeUnderTest, testCase.moduleTypeUnderTestBp2BuildMutator)
 		ctx.RegisterForBazelConversion()
 
 		_, errs := ctx.ParseFileList(dir, []string{"Android.bp"})
diff --git a/genrule/genrule.go b/genrule/genrule.go
index 66e5652f7..ddfb4596b 100644
--- a/genrule/genrule.go
+++ b/genrule/genrule.go
@@ -47,7 +47,7 @@ func RegisterGenruleBuildComponents(ctx android.RegistrationContext) {
 		ctx.BottomUp("genrule_tool_deps", toolDepsMutator).Parallel()
 	})
 
-	android.RegisterBp2BuildMutator("genrule", bp2buildMutator)
+	android.RegisterBp2BuildMutator("genrule", GenruleBp2Build)
 }
 
 var (
@@ -794,7 +794,7 @@ func BazelGenruleFactory() android.Module {
 	return module
 }
 
-func bp2buildMutator(ctx android.TopDownMutatorContext) {
+func GenruleBp2Build(ctx android.TopDownMutatorContext) {
 	if m, ok := ctx.Module().(*Module); ok {
 		name := "__bp2build__" + m.Name()
 		// Bazel only has the "tools" attribute.