diff --git a/android/testing.go b/android/testing.go
index 26f1e4d..aaf98f5 100644
--- a/android/testing.go
+++ b/android/testing.go
@@ -16,7 +16,6 @@
 
 import (
 	"fmt"
-	"path/filepath"
 	"regexp"
 	"strings"
 	"testing"
@@ -68,7 +67,11 @@
 	ctx.postDeps = append(ctx.postDeps, f)
 }
 
-func (ctx *TestContext) Register() {
+func (ctx *TestContext) Register(config Config) {
+	ctx.SetFs(config.fs)
+	if config.mockBpList != "" {
+		ctx.SetModuleListFile(config.mockBpList)
+	}
 	registerMutators(ctx.Context.Context, ctx.preArch, ctx.preDeps, ctx.postDeps)
 
 	ctx.RegisterSingletonType("env", EnvSingleton)
@@ -132,25 +135,6 @@
 		"\nall singletons: %v", name, allSingletonNames))
 }
 
-// MockFileSystem causes the Context to replace all reads with accesses to the provided map of
-// filenames to contents stored as a byte slice.
-func (ctx *TestContext) MockFileSystem(files map[string][]byte) {
-	// no module list file specified; find every file named Blueprints or Android.bp
-	pathsToParse := []string{}
-	for candidate := range files {
-		base := filepath.Base(candidate)
-		if base == "Blueprints" || base == "Android.bp" {
-			pathsToParse = append(pathsToParse, candidate)
-		}
-	}
-	if len(pathsToParse) < 1 {
-		panic(fmt.Sprintf("No Blueprint or Android.bp files found in mock filesystem: %v\n", files))
-	}
-	files[blueprint.MockModuleListFile] = []byte(strings.Join(pathsToParse, "\n"))
-
-	ctx.Context.MockFileSystem(files)
-}
-
 type testBuildProvider interface {
 	BuildParamsForTests() []BuildParams
 	RuleParamsForTests() map[blueprint.Rule]blueprint.RuleParams