2 files changed, 50 insertions, 0 deletions
diff --git a/android/paths.go b/android/paths.go
index 024432eae..c841372dc 100644
--- a/android/paths.go
+++ b/android/paths.go
@@ -118,6 +118,9 @@ type Path interface {
 type WritablePath interface {
 	Path
 
+	// return the path to the build directory.
+	buildDir() string
+
 	// the writablePath method doesn't directly do anything,
 	// but it allows a struct to distinguish between whether or not it implements the WritablePath interface
 	writablePath()
@@ -848,7 +851,12 @@ func (p OutputPath) WithoutRel() OutputPath {
 	return p
 }
 
+func (p OutputPath) buildDir() string {
+	return p.config.buildDir
+}
+
 var _ Path = OutputPath{}
+var _ WritablePath = OutputPath{}
 
 // PathForOutput joins the provided paths and returns an OutputPath that is
 // validated to not escape the build dir.
@@ -1151,6 +1159,13 @@ type InstallPath struct {
 	baseDir string // "../" for Make paths to convert "out/soong" to "out", "" for Soong paths
 }
 
+func (p InstallPath) buildDir() string {
+	return p.config.buildDir
+}
+
+var _ Path = InstallPath{}
+var _ WritablePath = InstallPath{}
+
 func (p InstallPath) writablePath() {}
 
 func (p InstallPath) String() string {
@@ -1302,6 +1317,10 @@ type PhonyPath struct {
 
 func (p PhonyPath) writablePath() {}
 
+func (p PhonyPath) buildDir() string {
+	return p.config.buildDir
+}
+
 var _ Path = PhonyPath{}
 var _ WritablePath = PhonyPath{}
 
diff --git a/android/testing.go b/android/testing.go
index aaf98f595..4f0591b1d 100644
--- a/android/testing.go
+++ b/android/testing.go
@@ -16,6 +16,7 @@ package android
 
 import (
 	"fmt"
+	"path/filepath"
 	"regexp"
 	"strings"
 	"testing"
@@ -411,3 +412,33 @@ func AndroidMkDataForTest(t *testing.T, config Config, bpPath string, mod bluepr
 	data.fillInData(config, bpPath, mod)
 	return data
 }
+
+// Normalize the path for testing.
+//
+// If the path is relative to the build directory then return the relative path
+// to avoid tests having to deal with the dynamically generated build directory.
+//
+// Otherwise, return the supplied path as it is almost certainly a source path
+// that is relative to the root of the source tree.
+//
+// The build and source paths should be distinguishable based on their contents.
+func NormalizePathForTesting(path Path) string {
+	p := path.String()
+	if w, ok := path.(WritablePath); ok {
+		rel, err := filepath.Rel(w.buildDir(), p)
+		if err != nil {
+			panic(err)
+		}
+		return rel
+	}
+	return p
+}
+
+func NormalizePathsForTesting(paths Paths) []string {
+	var result []string
+	for _, path := range paths {
+		relative := NormalizePathForTesting(path)
+		result = append(result, relative)
+	}
+	return result
+}