diff --git a/apex/apex_test.go b/apex/apex_test.go
index 1006a62..898b9e9 100644
--- a/apex/apex_test.go
+++ b/apex/apex_test.go
@@ -70,20 +70,16 @@
 // deprecated
 type testCustomizer func(fs map[string][]byte, config android.Config)
 
-func withFiles(files map[string][]byte) testCustomizer {
-	return func(fs map[string][]byte, config android.Config) {
-		for k, v := range files {
-			fs[k] = v
-		}
-	}
+func withFiles(files android.MockFS) android.FixturePreparer {
+	return files.AddToFixture()
 }
 
-func withTargets(targets map[android.OsType][]android.Target) testCustomizer {
-	return func(fs map[string][]byte, config android.Config) {
+func withTargets(targets map[android.OsType][]android.Target) android.FixturePreparer {
+	return android.FixtureModifyConfig(func(config android.Config) {
 		for k, v := range targets {
 			config.Targets[k] = v
 		}
-	}
+	})
 }
 
 // withNativeBridgeTargets sets configuration with targets including:
@@ -91,32 +87,38 @@
 // - X86 (secondary)
 // - Arm64 on X86_64 (native bridge)
 // - Arm on X86 (native bridge)
-func withNativeBridgeEnabled(_ map[string][]byte, config android.Config) {
-	config.Targets[android.Android] = []android.Target{
-		{Os: android.Android, Arch: android.Arch{ArchType: android.X86_64, ArchVariant: "silvermont", Abi: []string{"arm64-v8a"}},
-			NativeBridge: android.NativeBridgeDisabled, NativeBridgeHostArchName: "", NativeBridgeRelativePath: ""},
-		{Os: android.Android, Arch: android.Arch{ArchType: android.X86, ArchVariant: "silvermont", Abi: []string{"armeabi-v7a"}},
-			NativeBridge: android.NativeBridgeDisabled, NativeBridgeHostArchName: "", NativeBridgeRelativePath: ""},
-		{Os: android.Android, Arch: android.Arch{ArchType: android.Arm64, ArchVariant: "armv8-a", Abi: []string{"arm64-v8a"}},
-			NativeBridge: android.NativeBridgeEnabled, NativeBridgeHostArchName: "x86_64", NativeBridgeRelativePath: "arm64"},
-		{Os: android.Android, Arch: android.Arch{ArchType: android.Arm, ArchVariant: "armv7-a-neon", Abi: []string{"armeabi-v7a"}},
-			NativeBridge: android.NativeBridgeEnabled, NativeBridgeHostArchName: "x86", NativeBridgeRelativePath: "arm"},
-	}
+var withNativeBridgeEnabled = android.FixtureModifyConfig(
+	func(config android.Config) {
+		config.Targets[android.Android] = []android.Target{
+			{Os: android.Android, Arch: android.Arch{ArchType: android.X86_64, ArchVariant: "silvermont", Abi: []string{"arm64-v8a"}},
+				NativeBridge: android.NativeBridgeDisabled, NativeBridgeHostArchName: "", NativeBridgeRelativePath: ""},
+			{Os: android.Android, Arch: android.Arch{ArchType: android.X86, ArchVariant: "silvermont", Abi: []string{"armeabi-v7a"}},
+				NativeBridge: android.NativeBridgeDisabled, NativeBridgeHostArchName: "", NativeBridgeRelativePath: ""},
+			{Os: android.Android, Arch: android.Arch{ArchType: android.Arm64, ArchVariant: "armv8-a", Abi: []string{"arm64-v8a"}},
+				NativeBridge: android.NativeBridgeEnabled, NativeBridgeHostArchName: "x86_64", NativeBridgeRelativePath: "arm64"},
+			{Os: android.Android, Arch: android.Arch{ArchType: android.Arm, ArchVariant: "armv7-a-neon", Abi: []string{"armeabi-v7a"}},
+				NativeBridge: android.NativeBridgeEnabled, NativeBridgeHostArchName: "x86", NativeBridgeRelativePath: "arm"},
+		}
+	},
+)
+
+func withManifestPackageNameOverrides(specs []string) android.FixturePreparer {
+	return android.FixtureModifyProductVariables(func(variables android.FixtureProductVariables) {
+		variables.ManifestPackageNameOverrides = specs
+	})
 }
 
-func withManifestPackageNameOverrides(specs []string) testCustomizer {
-	return func(fs map[string][]byte, config android.Config) {
-		config.TestProductVariables.ManifestPackageNameOverrides = specs
-	}
-}
+var withBinder32bit = android.FixtureModifyProductVariables(
+	func(variables android.FixtureProductVariables) {
+		variables.Binder32bit = proptools.BoolPtr(true)
+	},
+)
 
-func withBinder32bit(_ map[string][]byte, config android.Config) {
-	config.TestProductVariables.Binder32bit = proptools.BoolPtr(true)
-}
-
-func withUnbundledBuild(_ map[string][]byte, config android.Config) {
-	config.TestProductVariables.Unbundled_build = proptools.BoolPtr(true)
-}
+var withUnbundledBuild = android.FixtureModifyProductVariables(
+	func(variables android.FixtureProductVariables) {
+		variables.Unbundled_build = proptools.BoolPtr(true)
+	},
+)
 
 var emptyFixtureFactory = android.NewFixtureFactory(&buildDir)