pkg/test: remove check that GOPATH is set

We can also use the implicit one, so don't require an explicit one.

Change-Id: Ie4712be849f40b8f8cc30f99d019dd863944289f

internal/osutil/paths.go

@@ -275,12 +275,19 @@ func NewJSONConfigParser() *jsonconfig.ConfigParser {
 // GoPackagePath returns the path to the provided Go package's
 // source directory.
 // pkg may be a path prefix without any *.go files.
-// The error is os.ErrNotExist if GOPATH is unset or the directory
-// doesn't exist in any GOPATH component.
+// The error is os.ErrNotExist if GOPATH is unset.
 func GoPackagePath(pkg string) (path string, err error) {
 	gp := os.Getenv("GOPATH")
 	if gp == "" {
-		return path, os.ErrNotExist
+		cmd := exec.Command("go", "env", "GOPATH")
+		out, err := cmd.Output()
+		if err != nil {
+			return "", fmt.Errorf("could not run 'go env GOPATH': %v, %s", err, out)
+		}
+		gp = strings.TrimSpace(string(out))
+		if gp == "" {
+			return "", os.ErrNotExist
+		}
 	}
 	for _, p := range filepath.SplitList(gp) {
 		dir := filepath.Join(p, "src", filepath.FromSlash(pkg))

pkg/test/world.go

@@ -57,9 +57,6 @@ type World struct {
 
 // pkSourceRoot returns the root of the source tree, or an error.
 func pkSourceRoot() (string, error) {
-	if os.Getenv("GOPATH") == "" {
-		return "", errors.New("GOPATH environment variable isn't set; required to run Perkeep integration tests")
-	}
 	root, err := osutil.GoPackagePath("perkeep.org")
 	if err == os.ErrNotExist {
 		return "", errors.New("directory \"perkeep.org\" not found under GOPATH/src; can't run Perkeep integration tests")
@@ -68,14 +65,14 @@ func pkSourceRoot() (string, error) {
 }
 
 // NewWorld returns a new test world.
-// It requires that GOPATH is set to find the "perkeep.org" root.
+// It uses the GOPATH (explicit or implicit) to find the "perkeep.org" root.
 func NewWorld() (*World, error) {
 	return WorldFromConfig("server-config.json")
 }
 
 // WorldFromConfig returns a new test world based on the given configuration file.
 // This cfg is the server config relative to pkg/test/testdata.
-// It requires that GOPATH is set to find the "perkeep.org" root.
+// It uses the GOPATH (explicit or implicit) to find the "perkeep.org" root.
 func WorldFromConfig(cfg string) (*World, error) {
 	root, err := pkSourceRoot()
 	if err != nil {