From afe8d2c6a556571174b6250c40b0be6834b2dc34 Mon Sep 17 00:00:00 2001
From: Andreas Bergmeier <abergmeier@gmx.net>
Date: Mon, 19 Mar 2018 00:49:43 +0100
Subject: [PATCH] Make DataFile work with Bazel, too.

Use new file skylarktest/bazeltest.go for handling Bazel.

- Update comment for DataFile to something more helpful.
- DataFile can now be replaced with Bazel variant
---
 eval_test.go                 |  4 ++--
 resolve/resolve_test.go      |  2 +-
 skylarkstruct/struct_test.go |  2 +-
 skylarktest/bazeltest.go     | 25 +++++++++++++++++++++++++
 skylarktest/skylarktest.go   | 14 ++++++++------
 syntax/parse_test.go         |  2 +-
 6 files changed, 38 insertions(+), 11 deletions(-)
 create mode 100644 skylarktest/bazeltest.go

diff --git a/eval_test.go b/eval_test.go
index e4d3e3d..6ab91bc 100644
--- a/eval_test.go
+++ b/eval_test.go
@@ -92,7 +92,7 @@ func TestEvalExpr(t *testing.T) {
 }
 
 func TestExecFile(t *testing.T) {
-	testdata := skylarktest.DataFile("skylark", ".")
+	testdata := skylarktest.DataFile("", ".")
 	thread := &skylark.Thread{Load: load}
 	skylarktest.SetReporter(thread, t)
 	for _, file := range []string{
@@ -342,7 +342,7 @@ f()
 }
 
 func Benchmark(b *testing.B) {
-	testdata := skylarktest.DataFile("skylark", ".")
+	testdata := skylarktest.DataFile("", ".")
 	thread := new(skylark.Thread)
 	for _, file := range []string{
 		"testdata/benchmark.sky",
diff --git a/resolve/resolve_test.go b/resolve/resolve_test.go
index c2fd9fd..e8cfb0d 100644
--- a/resolve/resolve_test.go
+++ b/resolve/resolve_test.go
@@ -15,7 +15,7 @@ import (
 )
 
 func TestResolve(t *testing.T) {
-	filename := skylarktest.DataFile("skylark/resolve", "testdata/resolve.sky")
+	filename := skylarktest.DataFile("resolve", "testdata/resolve.sky")
 	for _, chunk := range chunkedfile.Read(filename, t) {
 		f, err := syntax.Parse(filename, chunk.Source, 0)
 		if err != nil {
diff --git a/skylarkstruct/struct_test.go b/skylarkstruct/struct_test.go
index 8700c8a..e886a4e 100644
--- a/skylarkstruct/struct_test.go
+++ b/skylarkstruct/struct_test.go
@@ -24,7 +24,7 @@ func init() {
 }
 
 func Test(t *testing.T) {
-	testdata := skylarktest.DataFile("skylark/skylarkstruct", ".")
+	testdata := skylarktest.DataFile("skylarkstruct", ".")
 	thread := &skylark.Thread{Load: load}
 	skylarktest.SetReporter(thread, t)
 	filename := filepath.Join(testdata, "testdata/struct.sky")
diff --git a/skylarktest/bazeltest.go b/skylarktest/bazeltest.go
new file mode 100644
index 0000000..13197cc
--- /dev/null
+++ b/skylarktest/bazeltest.go
@@ -0,0 +1,25 @@
+// +build bazel
+
+// Copyright 2018 The Bazel Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Rebinds DataFile, so that it builds data paths as expected by Bazel.
+
+package skylarktest
+
+import (
+	"os"
+	"path/filepath"
+)
+
+func init() {
+	testDir := os.Getenv("TEST_SRCDIR")
+	DataFile = func(subdir, filename string) string {
+		// Late check testDir, to only panic when we actually need it.
+		if testDir == "" {
+			panic("Environment variable TEST_SRCDIR unset or empty.")
+		}
+		return filepath.Join(testDir, "com_github_google_skylark", subdir, filename)
+	}
+}
diff --git a/skylarktest/skylarktest.go b/skylarktest/skylarktest.go
index 9b71f0b..b526643 100644
--- a/skylarktest/skylarktest.go
+++ b/skylarktest/skylarktest.go
@@ -66,7 +66,7 @@ func LoadAssertModule() (skylark.StringDict, error) {
 			"struct":  skylark.NewBuiltin("struct", skylarkstruct.Make),
 			"freeze":  skylark.NewBuiltin("freeze", freeze),
 		}
-		filename := DataFile("skylark/skylarktest", "assert.sky")
+		filename := DataFile("skylarktest", "assert.sky")
 		thread := new(skylark.Thread)
 		assertErr = skylark.ExecFile(thread, filename, nil, globals)
 		// Expose only these items:
@@ -134,9 +134,11 @@ func freeze(thread *skylark.Thread, _ *skylark.Builtin, args skylark.Tuple, kwar
 }
 
 // DataFile returns the effective filename of the specified
-// test data resource.  The function abstracts differences between
-// 'go build', under which a test runs in its package directory,
-// and Blaze, under which a test runs in the root of the tree.
-var DataFile = func(pkgdir, filename string) string {
-	return filepath.Join(build.Default.GOPATH, "src/github.com/google", pkgdir, filename)
+// test data resource. The function abstracts differences between
+// - 'go build' (under which a test runs in its package directory),
+// - Blaze (under which a test runs in the root of the tree) and
+// - Bazel/rules_go (under which a test runs in a different package directory)
+// The default behavior works for 'go build'.
+var DataFile = func(subdir, filename string) string {
+	return filepath.Join(build.Default.GOPATH, "src/github.com/google/skylark", subdir, filename)
 }
diff --git a/syntax/parse_test.go b/syntax/parse_test.go
index d511d3f..e57b6df 100644
--- a/syntax/parse_test.go
+++ b/syntax/parse_test.go
@@ -332,7 +332,7 @@ func writeTree(out *bytes.Buffer, x reflect.Value) {
 }
 
 func TestParseErrors(t *testing.T) {
-	filename := skylarktest.DataFile("skylark/syntax", "testdata/errors.sky")
+	filename := skylarktest.DataFile("syntax", "testdata/errors.sky")
 	for _, chunk := range chunkedfile.Read(filename, t) {
 		_, err := syntax.Parse(filename, chunk.Source, 0)
 		switch err := err.(type) {