go.mod: use github.com/rogpeppe/go-internal/testscript

github.com/rogpeppe/testscript no longer maintain.
We should be use github.com/rogpeppe/go-internal/testscript which still
maintains.
Also, fix filepath.Walk logic on doc/tutorial/basics.TestScript. Might
be related github.com/rogpeppe/go-internal upstream change.

Change-Id: I16ca3f28b9138bf0fbd4cb242ce3f74fc3d66133
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/6081
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
Reviewed-by: Paul Jolly <paul@myitcv.org.uk>
diff --git a/cmd/cue/cmd/script_test.go b/cmd/cue/cmd/script_test.go
index c48d7e0..6e346e8 100644
--- a/cmd/cue/cmd/script_test.go
+++ b/cmd/cue/cmd/script_test.go
@@ -12,8 +12,8 @@
 	"strings"
 	"testing"
 
-	"github.com/rogpeppe/testscript"
-	"github.com/rogpeppe/testscript/txtar"
+	"github.com/rogpeppe/go-internal/testscript"
+	"github.com/rogpeppe/go-internal/txtar"
 
 	"cuelang.org/go/cue/errors"
 	"cuelang.org/go/cue/parser"
diff --git a/doc/tutorial/basics/script_test.go b/doc/tutorial/basics/script_test.go
index a171061..c91414e 100644
--- a/doc/tutorial/basics/script_test.go
+++ b/doc/tutorial/basics/script_test.go
@@ -8,8 +8,8 @@
 	"strings"
 	"testing"
 
-	"github.com/rogpeppe/testscript"
-	"github.com/rogpeppe/testscript/txtar"
+	"github.com/rogpeppe/go-internal/testscript"
+	"github.com/rogpeppe/go-internal/txtar"
 
 	"cuelang.org/go/cmd/cue/cmd"
 	"cuelang.org/go/cue/parser"
@@ -49,8 +49,8 @@
 
 func TestScript(t *testing.T) {
 	filepath.Walk(".", func(path string, info os.FileInfo, err error) error {
-		if !info.IsDir() {
-			return nil
+		if info.IsDir() {
+			return filepath.SkipDir
 		}
 		testscript.Run(t, testscript.Params{
 			Dir:           path,
diff --git a/go.mod b/go.mod
index 2a7d5ac..6f88451 100644
--- a/go.mod
+++ b/go.mod
@@ -10,7 +10,7 @@
 	github.com/lib/pq v1.0.0 // indirect
 	github.com/mpvl/unique v0.0.0-20150818121801-cbe035fff7de
 	github.com/pkg/errors v0.8.1 // indirect
-	github.com/rogpeppe/testscript v1.1.0
+	github.com/rogpeppe/go-internal v1.6.0
 	github.com/spf13/cobra v0.0.7
 	github.com/spf13/pflag v1.0.3
 	github.com/stretchr/testify v1.2.2
diff --git a/go.sum b/go.sum
index 901307b..92d881e 100644
--- a/go.sum
+++ b/go.sum
@@ -75,7 +75,6 @@
 github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
 github.com/oklog/ulid v1.3.1/go.mod h1:CirwcVhetQ6Lv90oh/F+FBtV6XMibvdAFo93nm5qn4U=
 github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/94hg7ilaic=
-github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
@@ -91,8 +90,8 @@
 github.com/prometheus/procfs v0.0.0-20190507164030-5867b95ac084/go.mod h1:TjEm7ze935MbeOT/UhFTIMYKhuLP4wbCsTZCD3I8kEA=
 github.com/prometheus/tsdb v0.7.1/go.mod h1:qhTCs0VvXwvX/y3TZrWD7rabWM+ijKTux40TwIPHuXU=
 github.com/rogpeppe/fastuuid v0.0.0-20150106093220-6724a57986af/go.mod h1:XWv6SoW27p1b0cqNHllgS5HIMJraePCO15w5zCzIWYg=
-github.com/rogpeppe/testscript v1.1.0 h1:NxTsoOBQ1zibxf6NDtzrjPbK56hDAteIcOTSINZHtow=
-github.com/rogpeppe/testscript v1.1.0/go.mod h1:lzMlnW8LS56mcdJoQYkrlzqOoTFCOemzt5LusJ93bDM=
+github.com/rogpeppe/go-internal v1.6.0 h1:IZRgg4sfrDH7nsAD1Y/Nwj+GzIfEwpJSLjCaNC3SbsI=
+github.com/rogpeppe/go-internal v1.6.0/go.mod h1:xXDCJY+GAPziupqXw64V24skbSoqbTEfhy4qGm1nDQc=
 github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
 github.com/sirupsen/logrus v1.2.0/go.mod h1:LxeOpSwHxABJmUn/MG1IvRgCAasNZTLOkJPxbbu5VWo=
diff --git a/internal/cuetxtar/txtar.go b/internal/cuetxtar/txtar.go
index f2b6804..658c818 100644
--- a/internal/cuetxtar/txtar.go
+++ b/internal/cuetxtar/txtar.go
@@ -28,7 +28,7 @@
 	"cuelang.org/go/cue/errors"
 	"cuelang.org/go/cue/load"
 	"github.com/google/go-cmp/cmp"
-	"github.com/rogpeppe/testscript/txtar"
+	"github.com/rogpeppe/go-internal/txtar"
 )
 
 // A TxTarTest represents a test run that process all CUE tests in the txtar