diff --git a/cmd/cue/cmd/cmd_test.go b/cmd/cue/cmd/cmd_test.go
deleted file mode 100644
index 7eec347..0000000
--- a/cmd/cue/cmd/cmd_test.go
+++ /dev/null
@@ -1,60 +0,0 @@
-// Copyright 2018 The CUE Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package cmd
-
-import (
-	"os"
-	"testing"
-
-	"cuelang.org/go/cue/errors"
-	"github.com/spf13/cobra"
-)
-
-func TestCmd(t *testing.T) {
-	cfg := printConfig(t)
-
-	testCases := []string{
-		"echo",
-		"run",
-		"run_list",
-		"baddisplay",
-		"errcode",
-		"http",
-		"print",
-	}
-	defer func() {
-		stdout = os.Stdout
-		stderr = os.Stderr
-	}()
-	for _, name := range testCases {
-		c := newRootCmd()
-		run := func(cmd *cobra.Command, args []string) error {
-			stdout = cmd.OutOrStdout()
-			stderr = c.Stderr()
-
-			tools, _ := buildTools(c, args)
-			cmd, err := addCustom(c, c.root, "command", name, tools)
-			if err != nil {
-				return err
-			}
-			err = executeTasks("command", name, tools)
-			if err != nil {
-				errors.Print(stdout, err, cfg)
-			}
-			return nil
-		}
-		runCommand(t, &cobra.Command{RunE: run}, "cmd_"+name)
-	}
-}
diff --git a/cmd/cue/cmd/common_test.go b/cmd/cue/cmd/common_test.go
index 8348106..018531c 100644
--- a/cmd/cue/cmd/common_test.go
+++ b/cmd/cue/cmd/common_test.go
@@ -16,17 +16,10 @@
 
 import (
 	"flag"
-	"fmt"
-	"io"
-	"io/ioutil"
 	"os"
-	"path/filepath"
-	"regexp"
 	"testing"
 
 	"cuelang.org/go/cue/errors"
-	"github.com/spf13/cobra"
-	"golang.org/x/sync/errgroup"
 )
 
 var _ = errors.Print
@@ -48,77 +41,3 @@
 		ToSlash: true,
 	}
 }
-
-func runCommand(t *testing.T, cmd *cobra.Command, name string, args ...string) {
-	t.Helper()
-
-	const dir = "./testdata"
-
-	cfg := printConfig(t)
-
-	_ = filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
-		t.Run(path, func(t *testing.T) {
-			if err != nil {
-				t.Fatal(err)
-			}
-			if !info.IsDir() || dir == path {
-				return
-			}
-			testfile := filepath.Join(path, name+".out")
-			bWant, err := ioutil.ReadFile(testfile)
-			if err != nil {
-				// Don't write the file if it doesn't exist, even in *update
-				// mode. We don't want to need to support all commands for all
-				// directories. Touch the file and use *update to create it.
-				return
-			}
-
-			extra := args
-			if len(args) == 0 {
-				extra = append(args, "./"+path)
-			}
-			cmd.SetArgs(extra)
-			rOut, wOut := io.Pipe()
-			cmd.SetOutput(wOut)
-			var bOut []byte
-			g := errgroup.Group{}
-			g.Go(func() error {
-				defer wOut.Close()
-				defer func() {
-					switch err := recover().(type) {
-					case nil:
-					case panicError:
-						errors.Print(wOut, err.Err, cfg)
-					case error:
-						errors.Print(wOut, err, cfg)
-					default:
-						fmt.Fprintln(wOut, err)
-					}
-				}()
-				return cmd.Execute()
-			})
-			g.Go(func() error {
-				bOut, err = ioutil.ReadAll(rOut)
-				re := regexp.MustCompile(`exit status \d`)
-				bOut = re.ReplaceAll(bOut, []byte("non-zero exist code"))
-				return err
-			})
-			if err := g.Wait(); err != nil {
-				t.Error(err)
-			}
-			if *update {
-				_ = ioutil.WriteFile(testfile, bOut, 0644)
-				return
-			}
-			got, want := string(bOut), string(bWant)
-			if got != want {
-				t.Errorf("\n got: %v\nwant: %v", got, want)
-			}
-		})
-		return nil
-	})
-}
-
-func TestLoadError(t *testing.T) {
-	runCommand(t, newEvalCmd(newRootCmd()), "loaderr", "non-existing", ".")
-}
diff --git a/cmd/cue/cmd/eval_test.go b/cmd/cue/cmd/eval_test.go
deleted file mode 100644
index 56c4c5a..0000000
--- a/cmd/cue/cmd/eval_test.go
+++ /dev/null
@@ -1,29 +0,0 @@
-// Copyright 2018 The CUE Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package cmd
-
-import "testing"
-
-func TestEval(t *testing.T) {
-	runCommand(t, newEvalCmd(newRootCmd()), "eval")
-
-	cmd := newEvalCmd(newRootCmd())
-	mustParseFlags(t, cmd, "-c", "-a")
-	runCommand(t, cmd, "eval_conc")
-
-	cmd = newEvalCmd(newRootCmd())
-	mustParseFlags(t, cmd, "-c", "-e", "b.a.b", "-e", "b.idx")
-	runCommand(t, cmd, "eval_expr")
-}
diff --git a/cmd/cue/cmd/export_test.go b/cmd/cue/cmd/export_test.go
deleted file mode 100644
index 9b9aac5..0000000
--- a/cmd/cue/cmd/export_test.go
+++ /dev/null
@@ -1,22 +0,0 @@
-// Copyright 2019 CUE Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package cmd
-
-import "testing"
-
-func TestExport(t *testing.T) {
-	runCommand(t, newExportCmd(newRootCmd()), "export")
-	runCommand(t, newExportCmd(newRootCmd()), "export_err")
-}
diff --git a/cmd/cue/cmd/fmt_test.go b/cmd/cue/cmd/fmt_test.go
deleted file mode 100644
index 7ecefab..0000000
--- a/cmd/cue/cmd/fmt_test.go
+++ /dev/null
@@ -1,22 +0,0 @@
-// Copyright 2019 CUE Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package cmd
-
-import "testing"
-
-func TestFmt(t *testing.T) {
-	cmd := newFmtCmd(newRootCmd())
-	runCommand(t, cmd, "fmt")
-}
diff --git a/cmd/cue/cmd/import_test.go b/cmd/cue/cmd/import_test.go
deleted file mode 100644
index c892fbd..0000000
--- a/cmd/cue/cmd/import_test.go
+++ /dev/null
@@ -1,42 +0,0 @@
-// Copyright 2018 The CUE Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package cmd
-
-import (
-	"testing"
-)
-
-func TestImport(t *testing.T) {
-	cmd := newImportCmd(newRootCmd())
-	mustParseFlags(t, cmd,
-		"-o", "-", "-f", "--files")
-	runCommand(t, cmd, "import_files")
-
-	cmd = newImportCmd(newRootCmd())
-	mustParseFlags(t, cmd,
-		"-o", "-", "-f", "-l", `"\(strings.ToLower(kind))" "\(name)"`)
-	runCommand(t, cmd, "import_path")
-
-	cmd = newImportCmd(newRootCmd())
-	mustParseFlags(t, cmd,
-		"-o", "-", "-f", "-l", `"\(strings.ToLower(kind))"`, "--list")
-	runCommand(t, cmd, "import_list")
-
-	cmd = newImportCmd(newRootCmd())
-	mustParseFlags(t, cmd,
-		"-o", "-", "-f", "--list",
-		"-l", `"\(strings.ToLower(kind))" "\(name)"`, "--recursive")
-	runCommand(t, cmd, "import_hoiststr")
-}
diff --git a/cmd/cue/cmd/root.go b/cmd/cue/cmd/root.go
index bf13a2a..2f89cb4 100644
--- a/cmd/cue/cmd/root.go
+++ b/cmd/cue/cmd/root.go
@@ -16,7 +16,9 @@
 
 import (
 	"context"
+	"fmt"
 	"io"
+	"os"
 	"strings"
 
 	"cuelang.org/go/cue/errors"
@@ -100,8 +102,19 @@
 	return c
 }
 
-// Main runs the cue tool. It loads the tool flags.
-func Main(ctx context.Context, args []string) (err error) {
+// Main runs the cue tool and returns the code for passing to os.Exit.
+func Main() int {
+	err := mainErr(context.Background(), os.Args[1:])
+	if err != nil {
+		if err != ErrPrintedError {
+			fmt.Fprintln(os.Stderr, err)
+		}
+		return 1
+	}
+	return 0
+}
+
+func mainErr(ctx context.Context, args []string) error {
 	cmd, err := New(args)
 	if err != nil {
 		return err
@@ -296,5 +309,5 @@
 }
 
 func exit() {
-	panic(panicError{errors.New("terminating because of errors")})
+	panic(panicError{ErrPrintedError})
 }
diff --git a/cmd/cue/cmd/script_test.go b/cmd/cue/cmd/script_test.go
new file mode 100644
index 0000000..0bb50a4
--- /dev/null
+++ b/cmd/cue/cmd/script_test.go
@@ -0,0 +1,21 @@
+package cmd
+
+import (
+	"os"
+	"testing"
+
+	"github.com/rogpeppe/testscript"
+)
+
+func TestScript(t *testing.T) {
+	testscript.Run(t, testscript.Params{
+		Dir:           "testdata/script",
+		UpdateScripts: *update,
+	})
+}
+
+func TestMain(m *testing.M) {
+	os.Exit(testscript.RunMain(m, map[string]func() int{
+		"cue": Main,
+	}))
+}
diff --git a/cmd/cue/cmd/testdata/cue.mod b/cmd/cue/cmd/testdata/cue.mod
deleted file mode 100644
index ab9fbdd..0000000
--- a/cmd/cue/cmd/testdata/cue.mod
+++ /dev/null
@@ -1,14 +0,0 @@
-// Copyright 2019 CUE Authors
-// 
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-// 
-//     http://www.apache.org/licenses/LICENSE-2.0
-// 
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
diff --git a/cmd/cue/cmd/testdata/export/export.cue b/cmd/cue/cmd/testdata/export/export.cue
deleted file mode 100644
index 5110493..0000000
--- a/cmd/cue/cmd/testdata/export/export.cue
+++ /dev/null
@@ -1,13 +0,0 @@
-package export
-
-One :: 1
-
-def: *One | int
-
-a: string
-a: "foo"
-
-s t u: "bar"
-s t v: {a: 1} | *{b: 2}
-
-l: [1, 2, 3]
diff --git a/cmd/cue/cmd/testdata/export/export.out b/cmd/cue/cmd/testdata/export/export.out
deleted file mode 100644
index 5911b5c..0000000
--- a/cmd/cue/cmd/testdata/export/export.out
+++ /dev/null
@@ -1,17 +0,0 @@
-{
-    "def": 1,
-    "a": "foo",
-    "s": {
-        "t": {
-            "u": "bar",
-            "v": {
-                "b": 2
-            }
-        }
-    },
-    "l": [
-        1,
-        2,
-        3
-    ]
-}
diff --git a/cmd/cue/cmd/testdata/exporterr/export_err.cue b/cmd/cue/cmd/testdata/exporterr/export_err.cue
deleted file mode 100644
index 480a942..0000000
--- a/cmd/cue/cmd/testdata/exporterr/export_err.cue
+++ /dev/null
@@ -1,5 +0,0 @@
-package exporterr
-
-a: {
-	b: [0, 1, {c: int}, 3]
-}
diff --git a/cmd/cue/cmd/testdata/exporterr/export_err.out b/cmd/cue/cmd/testdata/exporterr/export_err.out
deleted file mode 100644
index 8ce55eb..0000000
--- a/cmd/cue/cmd/testdata/exporterr/export_err.out
+++ /dev/null
@@ -1 +0,0 @@
-cue: marshal error at path a.b.2.c: cannot convert incomplete value "int" to JSON
diff --git a/cmd/cue/cmd/testdata/fmt/error.cue b/cmd/cue/cmd/testdata/fmt/error.cue
deleted file mode 100644
index 60465d6..0000000
--- a/cmd/cue/cmd/testdata/fmt/error.cue
+++ /dev/null
@@ -1,4 +0,0 @@
-import a.b "foo"
-
-a: 2
-bb: 3
\ No newline at end of file
diff --git a/cmd/cue/cmd/testdata/fmt/fmt.out b/cmd/cue/cmd/testdata/fmt/fmt.out
deleted file mode 100644
index 231cb6d..0000000
--- a/cmd/cue/cmd/testdata/fmt/fmt.out
+++ /dev/null
@@ -1,2 +0,0 @@
-expected 'STRING', found '.':
-    ./testdata/fmt/error.cue:1:9
diff --git a/cmd/cue/cmd/testdata/hello/cmd_echo.out b/cmd/cue/cmd/testdata/hello/cmd_echo.out
deleted file mode 100644
index ea2fd5c..0000000
--- a/cmd/cue/cmd/testdata/hello/cmd_echo.out
+++ /dev/null
@@ -1,2 +0,0 @@
-Hello World!
-
diff --git a/cmd/cue/cmd/testdata/hello/data.cue b/cmd/cue/cmd/testdata/hello/data.cue
deleted file mode 100644
index edbb1b6..0000000
--- a/cmd/cue/cmd/testdata/hello/data.cue
+++ /dev/null
@@ -1,3 +0,0 @@
-package hello
-
-who :: "World"
diff --git a/cmd/cue/cmd/testdata/hello/eval.out b/cmd/cue/cmd/testdata/hello/eval.out
deleted file mode 100644
index f8492ce..0000000
--- a/cmd/cue/cmd/testdata/hello/eval.out
+++ /dev/null
@@ -1,2 +0,0 @@
-who ::   "World"
-message: "Hello World!"
diff --git a/cmd/cue/cmd/testdata/hello/eval_conc.out b/cmd/cue/cmd/testdata/hello/eval_conc.out
deleted file mode 100644
index df67acc..0000000
--- a/cmd/cue/cmd/testdata/hello/eval_conc.out
+++ /dev/null
@@ -1 +0,0 @@
-message: "Hello World!"
diff --git a/cmd/cue/cmd/testdata/hello/export.out b/cmd/cue/cmd/testdata/hello/export.out
deleted file mode 100644
index cf38f26..0000000
--- a/cmd/cue/cmd/testdata/hello/export.out
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-    "message": "Hello World!"
-}
diff --git a/cmd/cue/cmd/testdata/hello/hello.cue b/cmd/cue/cmd/testdata/hello/hello.cue
deleted file mode 100644
index f8f8654..0000000
--- a/cmd/cue/cmd/testdata/hello/hello.cue
+++ /dev/null
@@ -1,3 +0,0 @@
-package hello
-
-message: "Hello \(who)!" // who declared in data.cue
diff --git a/cmd/cue/cmd/testdata/hello/hello_tool.cue b/cmd/cue/cmd/testdata/hello/hello_tool.cue
deleted file mode 100644
index b3a6f2d..0000000
--- a/cmd/cue/cmd/testdata/hello/hello_tool.cue
+++ /dev/null
@@ -1,14 +0,0 @@
-package hello
-
-command echo: {
-    task echo: {
-        kind:   "exec"
-        cmd:    "echo \(message)"
-        stdout: string
-    }
-
-    task display: {
-        kind: "print"
-        text: task.echo.stdout
-    }
-}
\ No newline at end of file
diff --git a/cmd/cue/cmd/testdata/hello/vet.out b/cmd/cue/cmd/testdata/hello/vet.out
deleted file mode 100644
index e69de29..0000000
--- a/cmd/cue/cmd/testdata/hello/vet.out
+++ /dev/null
diff --git a/cmd/cue/cmd/testdata/import/import_files.out b/cmd/cue/cmd/testdata/import/import_files.out
deleted file mode 100644
index 02c62bd..0000000
--- a/cmd/cue/cmd/testdata/import/import_files.out
+++ /dev/null
@@ -1,11 +0,0 @@
-kind: "Service"
-name: "booster"
-kind:     "Deployment"
-name:     "booster"
-replicas: 1
-kind: "Service"
-name: """
-		supplement
-		foo
-		"""
-json: "[1, 2]"
diff --git a/cmd/cue/cmd/testdata/import/import_hoiststr.out b/cmd/cue/cmd/testdata/import/import_hoiststr.out
deleted file mode 100644
index 4460c9d..0000000
--- a/cmd/cue/cmd/testdata/import/import_hoiststr.out
+++ /dev/null
@@ -1,22 +0,0 @@
-import xjson "encoding/json"
-
-service: {
-	booster: [{
-		kind: "Service"
-		name: "booster"
-	}]
-	"supplement\nfoo": [{
-		kind: "Service"
-		name: """
-		supplement
-		foo
-		"""
-		json: xjson.Marshal(_cue_json)
-		_cue_json = [1, 2]
-	}]
-}
-deployment booster: [{
-	kind:     "Deployment"
-	name:     "booster"
-	replicas: 1
-}]
diff --git a/cmd/cue/cmd/testdata/import/import_list.out b/cmd/cue/cmd/testdata/import/import_list.out
deleted file mode 100644
index c645992..0000000
--- a/cmd/cue/cmd/testdata/import/import_list.out
+++ /dev/null
@@ -1,16 +0,0 @@
-service: [{
-	kind: "Service"
-	name: "booster"
-}, {
-	kind: "Service"
-	name: """
-		supplement
-		foo
-		"""
-	json: "[1, 2]"
-}]
-deployment: [{
-	kind:     "Deployment"
-	name:     "booster"
-	replicas: 1
-}]
diff --git a/cmd/cue/cmd/testdata/import/import_path.out b/cmd/cue/cmd/testdata/import/import_path.out
deleted file mode 100644
index b668a2d..0000000
--- a/cmd/cue/cmd/testdata/import/import_path.out
+++ /dev/null
@@ -1,18 +0,0 @@
-
-service booster: {
-	kind: "Service"
-	name: "booster"
-}
-deployment booster: {
-	kind:     "Deployment"
-	name:     "booster"
-	replicas: 1
-}
-service "supplement\nfoo": {
-	kind: "Service"
-	name: """
-		supplement
-		foo
-		"""
-	json: "[1, 2]"
-}
diff --git a/cmd/cue/cmd/testdata/import/services.cue b/cmd/cue/cmd/testdata/import/services.cue
deleted file mode 100644
index c645992..0000000
--- a/cmd/cue/cmd/testdata/import/services.cue
+++ /dev/null
@@ -1,16 +0,0 @@
-service: [{
-	kind: "Service"
-	name: "booster"
-}, {
-	kind: "Service"
-	name: """
-		supplement
-		foo
-		"""
-	json: "[1, 2]"
-}]
-deployment: [{
-	kind:     "Deployment"
-	name:     "booster"
-	replicas: 1
-}]
diff --git a/cmd/cue/cmd/testdata/import/services.jsonl b/cmd/cue/cmd/testdata/import/services.jsonl
deleted file mode 100644
index e704fe0..0000000
--- a/cmd/cue/cmd/testdata/import/services.jsonl
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-    "kind": "Service",
-    "name": "booster"
-}
-{
-    "kind": "Deployment",
-    "name": "booster",
-    "replicas": 1
-}
-{
-    "kind": "Service",
-    "name": "supplement\nfoo",
-    "json": "[1, 2]"
-}
\ No newline at end of file
diff --git a/cmd/cue/cmd/testdata/loaderr/loaderr.out b/cmd/cue/cmd/testdata/loaderr/loaderr.out
deleted file mode 100644
index 68b2374..0000000
--- a/cmd/cue/cmd/testdata/loaderr/loaderr.out
+++ /dev/null
@@ -1,2 +0,0 @@
-cannot find package "non-existing"
-terminating because of errors
diff --git a/cmd/cue/cmd/testdata/partial/eval.out b/cmd/cue/cmd/testdata/partial/eval.out
deleted file mode 100644
index 73d0294..0000000
--- a/cmd/cue/cmd/testdata/partial/eval.out
+++ /dev/null
@@ -1,21 +0,0 @@
-def: 1
-sum: 1 | 2
-A = a
-b: {
-    idx: A[str]
-    a: {
-        b: 4
-    }
-    str: string
-}
-a: {
-    b: 3
-    c: 4
-}
-c: {
-    idx: 3
-    a: {
-        b: 4
-    }
-    str: "b"
-}
diff --git a/cmd/cue/cmd/testdata/partial/eval_conc.out b/cmd/cue/cmd/testdata/partial/eval_conc.out
deleted file mode 100644
index eae33c1..0000000
--- a/cmd/cue/cmd/testdata/partial/eval_conc.out
+++ /dev/null
@@ -1,6 +0,0 @@
-sum: incomplete value ((1 | 2)):
-    ./testdata/partial/partial.cue:4:6
-b.idx: invalid non-ground value string (must be concrete int|string):
-    ./testdata/partial/partial.cue:7:9
-b.str: incomplete value (string):
-    ./testdata/partial/partial.cue:8:7
diff --git a/cmd/cue/cmd/testdata/partial/eval_expr.out b/cmd/cue/cmd/testdata/partial/eval_expr.out
deleted file mode 100644
index 0e251dd..0000000
--- a/cmd/cue/cmd/testdata/partial/eval_expr.out
+++ /dev/null
@@ -1,5 +0,0 @@
-// b.a.b
-4
-// b.idx
-invalid non-ground value string (must be concrete int|string):
-    ./testdata/partial/partial.cue:7:9
diff --git a/cmd/cue/cmd/testdata/partial/partial.cue b/cmd/cue/cmd/testdata/partial/partial.cue
deleted file mode 100644
index ce33304..0000000
--- a/cmd/cue/cmd/testdata/partial/partial.cue
+++ /dev/null
@@ -1,15 +0,0 @@
-package partial
-
-def: *1 | int
-sum: 1 | 2
-
-b: {
-	idx: a[str] // should resolve to top-level `a`
-	str: string
-}
-b a b: 4
-a: {
-	b: 3
-	c: 4
-}
-c: b & {str: "b"}
diff --git a/cmd/cue/cmd/testdata/partial/vet.out b/cmd/cue/cmd/testdata/partial/vet.out
deleted file mode 100644
index e696e99..0000000
--- a/cmd/cue/cmd/testdata/partial/vet.out
+++ /dev/null
@@ -1 +0,0 @@
-some instances are incomplete; use the -c flag to show errors or suppress this message
diff --git a/cmd/cue/cmd/testdata/partial/vet_conc.out b/cmd/cue/cmd/testdata/partial/vet_conc.out
deleted file mode 100644
index eae33c1..0000000
--- a/cmd/cue/cmd/testdata/partial/vet_conc.out
+++ /dev/null
@@ -1,6 +0,0 @@
-sum: incomplete value ((1 | 2)):
-    ./testdata/partial/partial.cue:4:6
-b.idx: invalid non-ground value string (must be concrete int|string):
-    ./testdata/partial/partial.cue:7:9
-b.str: incomplete value (string):
-    ./testdata/partial/partial.cue:8:7
diff --git a/cmd/cue/cmd/testdata/script/cmd_baddisplay.txt b/cmd/cue/cmd/testdata/script/cmd_baddisplay.txt
new file mode 100644
index 0000000..3302f7e
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/cmd_baddisplay.txt
@@ -0,0 +1,21 @@
+! cue cmd baddisplay
+! stdout .
+cmp stderr cmd_baddisplay.out
+
+-- cmd_baddisplay.out --
+text: conflicting values 42 and string (mismatched types int and string):
+    ./task_tool.cue:6:9
+    tool/cli:4:9
+-- task.cue --
+package home
+message: "Hello world!"
+
+-- task_tool.cue --
+package home
+
+command baddisplay: {
+	task display: {
+		kind: "print"
+		text: 42
+	}
+}
diff --git a/cmd/cue/cmd/testdata/script/cmd_echo.txt b/cmd/cue/cmd/testdata/script/cmd_echo.txt
new file mode 100644
index 0000000..c47fa89
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/cmd_echo.txt
@@ -0,0 +1,29 @@
+cue cmd echo
+cmp stdout expect-stdout
+-- expect-stdout --
+Hello World!
+
+-- data.cue --
+package hello
+
+who :: "World"
+-- hello.cue --
+package hello
+
+message: "Hello \(who)!" // who declared in data.cue
+-- hello_tool.cue --
+package hello
+
+command echo: {
+    task echo: {
+        kind:   "exec"
+        cmd:    "echo \(message)"
+        stdout: string
+    }
+
+    task display: {
+        kind: "print"
+        text: task.echo.stdout
+    }
+}
+-- cue.mod --
diff --git a/cmd/cue/cmd/testdata/script/cmd_errcode.txt b/cmd/cue/cmd/testdata/script/cmd_errcode.txt
new file mode 100644
index 0000000..352d8c3
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/cmd_errcode.txt
@@ -0,0 +1,19 @@
+! cue cmd errcode
+! stdout .
+cmp stderr cmd_baddisplay.out
+
+-- cmd_baddisplay.out --
+command "ls --badflags" failed: exit status 2
+-- task.cue --
+package home
+message: "Hello world!"
+
+-- task_tool.cue --
+package home
+
+command errcode: {
+	task bad: exec.Run & {
+		kind:   "exec"
+		cmd:    "ls --badflags"
+		stderr: string // suppress error message
+	}}
diff --git a/cmd/cue/cmd/testdata/script/cmd_http.txt b/cmd/cue/cmd/testdata/script/cmd_http.txt
new file mode 100644
index 0000000..2ce28ee
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/cmd_http.txt
@@ -0,0 +1,32 @@
+cue cmd http
+cmp stdout cmd_http.out
+-- cmd_http.out --
+{"data":"I'll be back!","when":"now"}
+
+-- task_tool.cue --
+
+package home
+
+command http: {
+	task testserver: {
+		kind: "testserver"
+		url:  string
+	}
+	task http: {
+		kind:   "http"
+		method: "POST"
+		url:    task.testserver.url
+
+		request body:  "I'll be back!"
+		response body: string // TODO: allow this to be a struct, parsing the body.
+	}
+	task print: {
+		kind: "print"
+		text: task.http.response.body
+	}
+}
+
+-- task.cue --
+package home
+
+message: "Hello world!"
diff --git a/cmd/cue/cmd/testdata/script/cmd_print.txt b/cmd/cue/cmd/testdata/script/cmd_print.txt
new file mode 100644
index 0000000..5ebf1c0
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/cmd_print.txt
@@ -0,0 +1,38 @@
+cue cmd print
+cmp stdout expect-stdout
+
+-- expect-stdout --
+t.1.
+.t.2.
+
+-- task_tool.cue --
+package home
+
+import (
+	"tool/exec"
+	"strings"
+)
+
+command print: {
+	task: {
+		t1: exec.Run & {
+			cmd: ["sh", "-c", "sleep 1; echo t1"]
+			stdout: string
+		}
+		t2: exec.Run & {
+			cmd: ["sh", "-c", "sleep 1; echo t2"]
+			stdout: string
+		}
+		t3: cli.Print & {
+			text: (f & {arg: t1.stdout + t2.stdout}).result
+		}
+	}
+}
+
+f :: {
+    arg: string
+    result: strings.Join(strings.Split(arg, ""), ".")
+}
+-- task.cue --
+package home
+-- cue.mod --
diff --git a/cmd/cue/cmd/testdata/script/cmd_run.txt b/cmd/cue/cmd/testdata/script/cmd_run.txt
new file mode 100644
index 0000000..51abff7
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/cmd_run.txt
@@ -0,0 +1,33 @@
+cue cmd run
+cmp stdout run.out
+
+-- run.out --
+Hello world!
+
+-- task.cue --
+package home
+message: "Hello world!"
+
+-- task_tool.cue --
+package home
+
+command run: runBase & {
+	task echo cmd: "echo \(message)"
+}
+
+-- base_tool.cue --
+package home
+
+// deliberately put in another file to test resolving top-level identifiers
+// in different files.
+runBase: {
+	task echo: {
+		kind:   "exec"
+		stdout: string
+	}
+
+	task display: {
+		kind: "print"
+		text: task.echo.stdout
+	}
+}
diff --git a/cmd/cue/cmd/testdata/script/cmd_run_list.txt b/cmd/cue/cmd/testdata/script/cmd_run_list.txt
new file mode 100644
index 0000000..66681e2
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/cmd_run_list.txt
@@ -0,0 +1,33 @@
+cue cmd run_list
+cmp stdout run_list.out
+
+-- run_list.out --
+Hello world!
+
+-- task.cue --
+package home
+message: "Hello world!"
+
+-- task_tool.cue --
+package home
+
+command run_list: runBase & {
+	task echo cmd: ["echo", message]
+}
+
+-- base_tool.cue --
+package home
+
+// deliberately put in another file to test resolving top-level identifiers
+// in different files.
+runBase: {
+	task echo: {
+		kind:   "exec"
+		stdout: string
+	}
+
+	task display: {
+		kind: "print"
+		text: task.echo.stdout
+	}
+}
diff --git a/cmd/cue/cmd/testdata/script/eval_concrete.txt b/cmd/cue/cmd/testdata/script/eval_concrete.txt
new file mode 100644
index 0000000..ccc755e
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/eval_concrete.txt
@@ -0,0 +1,16 @@
+cue eval -c -a
+cmp stdout eval_conc.out
+
+-- eval_conc.out --
+message: "Hello World!"
+-- cmd_echo.out --
+Hello World!
+
+-- data.cue --
+package hello
+
+who :: "World"
+-- hello.cue --
+package hello
+
+message: "Hello \(who)!" // who declared in data.cue
diff --git a/cmd/cue/cmd/testdata/script/eval_expr.txt b/cmd/cue/cmd/testdata/script/eval_expr.txt
new file mode 100644
index 0000000..6475b28
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/eval_expr.txt
@@ -0,0 +1,28 @@
+! cue eval -c -e b.a.b -e b.idx
+cmp stderr expect-stderr
+cmp stdout expect-stdout
+
+-- expect-stdout --
+// b.a.b
+4
+// b.idx
+-- expect-stderr --
+invalid non-ground value string (must be concrete int|string):
+    ./partial.cue:7:9
+-- partial.cue --
+package partial
+
+def: *1 | int
+sum: 1 | 2
+
+b: {
+	idx: a[str] // should resolve to top-level `a`
+	str: string
+}
+b a b: 4
+a: {
+	b: 3
+	c: 4
+}
+c: b & {str: "b"}
+
diff --git a/cmd/cue/cmd/testdata/script/eval_loaderr.txt b/cmd/cue/cmd/testdata/script/eval_loaderr.txt
new file mode 100644
index 0000000..3edd62b
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/eval_loaderr.txt
@@ -0,0 +1,6 @@
+! cue eval non-existing .
+! stdout .
+cmp stderr expect-stderr
+
+-- expect-stderr --
+cannot find package "non-existing"
diff --git a/cmd/cue/cmd/testdata/script/eval_tool.txt b/cmd/cue/cmd/testdata/script/eval_tool.txt
new file mode 100644
index 0000000..43aa9d6
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/eval_tool.txt
@@ -0,0 +1,15 @@
+cue eval
+cmp stdout expect-stdout
+
+-- expect-stdout --
+message: "Hello world!"
+-- task.cue --
+package home
+message: "Hello world!"
+
+-- task_tool.cue --
+package home
+
+command run_list: runBase & {
+	task echo cmd: ["echo", message]
+}
diff --git a/cmd/cue/cmd/testdata/script/export.txt b/cmd/cue/cmd/testdata/script/export.txt
new file mode 100644
index 0000000..6d70421
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/export.txt
@@ -0,0 +1,15 @@
+cue export ./hello
+cmp stdout expect-stdout
+-- expect-stdout --
+{
+    "message": "Hello World!"
+}
+-- hello/data.cue --
+package hello
+
+who :: "World"
+-- hello/hello.cue --
+package hello
+
+message: "Hello \(who)!" // who declared in data.cue
+-- hello/cue.mod --
diff --git a/cmd/cue/cmd/testdata/script/export_err.txt b/cmd/cue/cmd/testdata/script/export_err.txt
new file mode 100644
index 0000000..7cd9c72
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/export_err.txt
@@ -0,0 +1,11 @@
+cue export ./exporterr
+cmp stdout expect-stdout
+-- expect-stdout --
+cue: marshal error at path a.b.2.c: cannot convert incomplete value "int" to JSON
+-- exporterr/export_err.cue --
+package exporterr
+
+a: {
+	b: [0, 1, {c: int}, 3]
+}
+-- exporterr/cue.mod --
diff --git a/cmd/cue/cmd/testdata/script/fmt.txt b/cmd/cue/cmd/testdata/script/fmt.txt
new file mode 100644
index 0000000..2ce05d6
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/fmt.txt
@@ -0,0 +1,11 @@
+! cue fmt ./fmt
+cmp stderr expect-stderr
+-- expect-stderr --
+expected 'STRING', found '.':
+    ./fmt/error.cue:1:9
+-- fmt/error.cue --
+import a.b "foo"
+
+a: 2
+bb: 3
+-- fmt/cue.mod --
diff --git a/cmd/cue/cmd/testdata/script/import_files.txt b/cmd/cue/cmd/testdata/script/import_files.txt
new file mode 100644
index 0000000..76be294
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/import_files.txt
@@ -0,0 +1,30 @@
+cue import -o - -f --files ./import
+cmp stdout expect-stdout
+-- expect-stdout --
+kind: "Service"
+name: "booster"
+kind:     "Deployment"
+name:     "booster"
+replicas: 1
+kind: "Service"
+name: """
+		supplement
+		foo
+		"""
+json: "[1, 2]"
+-- import/services.jsonl --
+{
+    "kind": "Service",
+    "name": "booster"
+}
+{
+    "kind": "Deployment",
+    "name": "booster",
+    "replicas": 1
+}
+{
+    "kind": "Service",
+    "name": "supplement\nfoo",
+    "json": "[1, 2]"
+}
+-- cue.mod --
diff --git a/cmd/cue/cmd/testdata/script/import_hoiststr.txt b/cmd/cue/cmd/testdata/script/import_hoiststr.txt
new file mode 100644
index 0000000..266e99e
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/import_hoiststr.txt
@@ -0,0 +1,58 @@
+cue import -o - -f --list -l '"\(strings.ToLower(kind))" "\(name)"' --recursive ./import
+cmp stdout expect-stdout
+-- expect-stdout --
+import xjson "encoding/json"
+
+service: {
+	booster: [{
+		kind: "Service"
+		name: "booster"
+	}]
+	"supplement\nfoo": [{
+		kind: "Service"
+		name: """
+		supplement
+		foo
+		"""
+		json: xjson.Marshal(_cue_json)
+		_cue_json = [1, 2]
+	}]
+}
+deployment booster: [{
+	kind:     "Deployment"
+	name:     "booster"
+	replicas: 1
+}]
+-- import/services.cue --
+service: [{
+	kind: "Service"
+	name: "booster"
+}, {
+	kind: "Service"
+	name: """
+		supplement
+		foo
+		"""
+	json: "[1, 2]"
+}]
+deployment: [{
+	kind:     "Deployment"
+	name:     "booster"
+	replicas: 1
+}]
+-- import/services.jsonl --
+{
+    "kind": "Service",
+    "name": "booster"
+}
+{
+    "kind": "Deployment",
+    "name": "booster",
+    "replicas": 1
+}
+{
+    "kind": "Service",
+    "name": "supplement\nfoo",
+    "json": "[1, 2]"
+}
+-- cue.mod --
diff --git a/cmd/cue/cmd/testdata/script/import_list.txt b/cmd/cue/cmd/testdata/script/import_list.txt
new file mode 100644
index 0000000..8985511
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/import_list.txt
@@ -0,0 +1,52 @@
+cue import -o - -f -l "\(strings.ToLower(kind))" --list ./import
+cmp stdout expect-stdout
+-- expect-stdout --
+service: [{
+	kind: "Service"
+	name: "booster"
+}, {
+	kind: "Service"
+	name: """
+		supplement
+		foo
+		"""
+	json: "[1, 2]"
+}]
+deployment: [{
+	kind:     "Deployment"
+	name:     "booster"
+	replicas: 1
+}]
+-- import/services.cue --
+service: [{
+	kind: "Service"
+	name: "booster"
+}, {
+	kind: "Service"
+	name: """
+		supplement
+		foo
+		"""
+	json: "[1, 2]"
+}]
+deployment: [{
+	kind:     "Deployment"
+	name:     "booster"
+	replicas: 1
+}]
+-- import/services.jsonl --
+{
+    "kind": "Service",
+    "name": "booster"
+}
+{
+    "kind": "Deployment",
+    "name": "booster",
+    "replicas": 1
+}
+{
+    "kind": "Service",
+    "name": "supplement\nfoo",
+    "json": "[1, 2]"
+}
+-- cue.mod --
diff --git a/cmd/cue/cmd/testdata/script/import_path.txt b/cmd/cue/cmd/testdata/script/import_path.txt
new file mode 100644
index 0000000..80618e2
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/import_path.txt
@@ -0,0 +1,54 @@
+cue import -o - -f -l '"\(strings.ToLower(kind))" "\(name)"' ./import
+cmp stdout expect-stdout
+-- expect-stdout --
+
+service booster: {
+	kind: "Service"
+	name: "booster"
+}
+deployment booster: {
+	kind:     "Deployment"
+	name:     "booster"
+	replicas: 1
+}
+service "supplement\nfoo": {
+	kind: "Service"
+	name: """
+		supplement
+		foo
+		"""
+	json: "[1, 2]"
+}
+-- import/services.cue --
+service: [{
+	kind: "Service"
+	name: "booster"
+}, {
+	kind: "Service"
+	name: """
+		supplement
+		foo
+		"""
+	json: "[1, 2]"
+}]
+deployment: [{
+	kind:     "Deployment"
+	name:     "booster"
+	replicas: 1
+}]
+-- import/services.jsonl --
+{
+    "kind": "Service",
+    "name": "booster"
+}
+{
+    "kind": "Deployment",
+    "name": "booster",
+    "replicas": 1
+}
+{
+    "kind": "Service",
+    "name": "supplement\nfoo",
+    "json": "[1, 2]"
+}
+-- cue.mod --
diff --git a/cmd/cue/cmd/testdata/script/trim.txt b/cmd/cue/cmd/testdata/script/trim.txt
new file mode 100644
index 0000000..b437ddf
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/trim.txt
@@ -0,0 +1,117 @@
+cue trim -o - ./trim
+cmp stdout expect-stdout
+-- expect-stdout --
+package trim
+
+foo <Name>: {
+	_value: string
+
+	a: 4
+	b: string
+	d: 8
+	e: "foo"
+	f: ">> \( _value) <<"
+	n: 5
+
+	list: ["foo", 8.0]
+
+	struct: {a: 3.0}
+
+	sList: [{a: 8, b: string}, {a: 9, b: *"foo" | string}]
+	rList: [{a: "a"}]
+	rcList: [{a: "a", c: b}]
+
+	t <Name>: {
+		x: >=0 & <=5
+	}
+}
+
+foo bar: {
+	_value: "here"
+	b:      "foo"
+	c:      45
+
+	sList: [{b: "foo"}, {}]
+}
+
+foo baz: {}
+
+foo multipath: {
+	t <Name>: {
+		// Combined with the other template, we know the value must be 5 and
+		// thus the entry below can be eliminated.
+		x: >=5 & <=8
+	}
+
+	t u: {
+	}
+}
+
+// TODO: top-level fields are currently not removed.
+group: {
+	for k, v in foo {
+		comp "\(k)": v
+	}
+
+	comp bar: {
+		aa: 8 // new value
+	}
+}
+-- trim/trim.cue --
+package trim
+
+foo <Name>: {
+	_value: string
+
+	a: 4
+	b: string
+	d: 8
+	e: "foo"
+	f: ">> \( _value) <<"
+	n: 5
+
+	list: ["foo", 8.0]
+
+	struct: {a: 3.0}
+
+	sList: [{a: 8, b: string}, {a: 9, b: *"foo" | string}]
+	rList: [{a: "a"}]
+	rcList: [{a: "a", c: b}]
+
+	t <Name>: {
+		x: >=0 & <=5
+	}
+}
+
+foo bar: {
+	_value: "here"
+	b:      "foo"
+	c:      45
+
+	sList: [{b: "foo"}, {}]
+}
+
+foo baz: {}
+
+foo multipath: {
+	t <Name>: {
+		// Combined with the other template, we know the value must be 5 and
+		// thus the entry below can be eliminated.
+		x: >=5 & <=8
+	}
+
+	t u: {
+	}
+}
+
+// TODO: top-level fields are currently not removed.
+group: {
+	for k, v in foo {
+		comp "\(k)": v
+	}
+
+	comp bar: {
+		aa: 8 // new value
+	}
+}
+-- cue.mod --
diff --git a/cmd/cue/cmd/testdata/script/vet.txt b/cmd/cue/cmd/testdata/script/vet.txt
new file mode 100644
index 0000000..68e3664
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/vet.txt
@@ -0,0 +1,21 @@
+! cue vet
+cmp stderr expect-stderr
+
+-- expect-stderr --
+some instances are incomplete; use the -c flag to show errors or suppress this message
+-- partial.cue --
+package partial
+
+def: *1 | int
+sum: 1 | 2
+
+b: {
+	idx: a[str] // should resolve to top-level `a`
+	str: string
+}
+b a b: 4
+a: {
+	b: 3
+	c: 4
+}
+c: b & {str: "b"}
diff --git a/cmd/cue/cmd/testdata/script/vet_concrete.txt b/cmd/cue/cmd/testdata/script/vet_concrete.txt
new file mode 100644
index 0000000..6d557da
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/vet_concrete.txt
@@ -0,0 +1,25 @@
+! cue vet -c
+cmp stderr expect-stderr
+-- expect-stderr --
+sum: incomplete value ((1 | 2)):
+    ./partial.cue:4:6
+b.idx: invalid non-ground value string (must be concrete int|string):
+    ./partial.cue:7:9
+b.str: incomplete value (string):
+    ./partial.cue:8:7
+-- partial.cue --
+package partial
+
+def: *1 | int
+sum: 1 | 2
+
+b: {
+	idx: a[str] // should resolve to top-level `a`
+	str: string
+}
+b a b: 4
+a: {
+	b: 3
+	c: 4
+}
+c: b & {str: "b"}
diff --git a/cmd/cue/cmd/testdata/script/vet_expr.txt b/cmd/cue/cmd/testdata/script/vet_expr.txt
new file mode 100644
index 0000000..e96888c
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/vet_expr.txt
@@ -0,0 +1,34 @@
+! cue vet -e File vet.cue data.yaml
+cmp stderr expect-stderr
+
+-- expect-stderr --
+field "skip" not allowed in closed struct:
+    ./vet.cue:4:9
+-- vet.cue --
+
+translations <_> lang: string
+
+File :: {
+	translations: {...}
+}
+-- data.yaml --
+# translated messages
+translations:
+  hello:
+    lang: gsw
+    text: Grüetzi
+---
+translations:
+  hello:
+    text: Hoi
+---
+translations:
+  hello:
+    lang: no
+    text: Hallo
+---
+translations:
+  hello:
+    lang: nl
+    text: Hallo
+skip: true
diff --git a/cmd/cue/cmd/testdata/script/vet_file.txt b/cmd/cue/cmd/testdata/script/vet_file.txt
new file mode 100644
index 0000000..b000daf
--- /dev/null
+++ b/cmd/cue/cmd/testdata/script/vet_file.txt
@@ -0,0 +1,37 @@
+! cue vet ./vet.cue ./data.yaml
+cmp stderr expect-stderr
+
+-- expect-stderr --
+translations.hello.lang: incomplete value (string):
+    ./vet.cue:2:24
+translations.hello.lang: conflicting values false and string (mismatched types bool and string):
+    ./data.yaml:13:11
+    ./vet.cue:2:24
+-- vet.cue --
+
+translations <_> lang: string
+
+File :: {
+	translations: {...}
+}
+-- data.yaml --
+# translated messages
+translations:
+  hello:
+    lang: gsw
+    text: Grüetzi
+---
+translations:
+  hello:
+    text: Hoi
+---
+translations:
+  hello:
+    lang: no
+    text: Hallo
+---
+translations:
+  hello:
+    lang: nl
+    text: Hallo
+skip: true
diff --git a/cmd/cue/cmd/testdata/tasks/base_tool.cue b/cmd/cue/cmd/testdata/tasks/base_tool.cue
deleted file mode 100644
index 1787a94..0000000
--- a/cmd/cue/cmd/testdata/tasks/base_tool.cue
+++ /dev/null
@@ -1,15 +0,0 @@
-package home
-
-// deliberately put in another file to test resolving top-level identifiers
-// in different files.
-runBase: {
-	task echo: {
-		kind:   "exec"
-		stdout: string
-	}
-
-	task display: {
-		kind: "print"
-		text: task.echo.stdout
-	}
-}
diff --git a/cmd/cue/cmd/testdata/tasks/cmd_baddisplay.out b/cmd/cue/cmd/testdata/tasks/cmd_baddisplay.out
deleted file mode 100644
index 2d64bfb..0000000
--- a/cmd/cue/cmd/testdata/tasks/cmd_baddisplay.out
+++ /dev/null
@@ -1,3 +0,0 @@
-text: conflicting values 42 and string (mismatched types int and string):
-    ./testdata/tasks/task_tool.cue:31:9
-    tool/cli:4:9
diff --git a/cmd/cue/cmd/testdata/tasks/cmd_errcode.out b/cmd/cue/cmd/testdata/tasks/cmd_errcode.out
deleted file mode 100644
index 08e9a2b..0000000
--- a/cmd/cue/cmd/testdata/tasks/cmd_errcode.out
+++ /dev/null
@@ -1 +0,0 @@
-command "ls --badflags" failed: non-zero exist code
diff --git a/cmd/cue/cmd/testdata/tasks/cmd_http.out b/cmd/cue/cmd/testdata/tasks/cmd_http.out
deleted file mode 100644
index 058b2c2..0000000
--- a/cmd/cue/cmd/testdata/tasks/cmd_http.out
+++ /dev/null
@@ -1,2 +0,0 @@
-{"data":"I'll be back!","when":"now"}
-
diff --git a/cmd/cue/cmd/testdata/tasks/cmd_print.out b/cmd/cue/cmd/testdata/tasks/cmd_print.out
deleted file mode 100644
index 5572191..0000000
--- a/cmd/cue/cmd/testdata/tasks/cmd_print.out
+++ /dev/null
@@ -1,3 +0,0 @@
-t.1.
-.t.2.
-
diff --git a/cmd/cue/cmd/testdata/tasks/cmd_run.out b/cmd/cue/cmd/testdata/tasks/cmd_run.out
deleted file mode 100644
index 47ee769..0000000
--- a/cmd/cue/cmd/testdata/tasks/cmd_run.out
+++ /dev/null
@@ -1,2 +0,0 @@
-Hello world!
-
diff --git a/cmd/cue/cmd/testdata/tasks/cmd_run_list.out b/cmd/cue/cmd/testdata/tasks/cmd_run_list.out
deleted file mode 100644
index 47ee769..0000000
--- a/cmd/cue/cmd/testdata/tasks/cmd_run_list.out
+++ /dev/null
@@ -1,2 +0,0 @@
-Hello world!
-
diff --git a/cmd/cue/cmd/testdata/tasks/eval.out b/cmd/cue/cmd/testdata/tasks/eval.out
deleted file mode 100644
index aefec3e..0000000
--- a/cmd/cue/cmd/testdata/tasks/eval.out
+++ /dev/null
@@ -1 +0,0 @@
-message: "Hello world!"
diff --git a/cmd/cue/cmd/testdata/tasks/task.cue b/cmd/cue/cmd/testdata/tasks/task.cue
deleted file mode 100644
index cb91d4f..0000000
--- a/cmd/cue/cmd/testdata/tasks/task.cue
+++ /dev/null
@@ -1,3 +0,0 @@
-package home
-
-message: "Hello world!"
diff --git a/cmd/cue/cmd/testdata/tasks/task_tool.cue b/cmd/cue/cmd/testdata/tasks/task_tool.cue
deleted file mode 100644
index 05383ec..0000000
--- a/cmd/cue/cmd/testdata/tasks/task_tool.cue
+++ /dev/null
@@ -1,73 +0,0 @@
-package home
-
-import "tool/exec"
-
-command run: runBase & {
-	task echo cmd: "echo \(message)"
-}
-
-command run_list: runBase & {
-	task echo cmd: ["echo", message]
-}
-
-command errcode: {
-	task bad: exec.Run & {
-		kind:   "exec"
-		cmd:    "ls --badflags"
-		stderr: string // suppress error message
-	}}
-
-// TODO: capture stdout and stderr for tests.
-command runRedirect: {
-	task echo: exec.Run & {
-		kind: "exec"
-		cmd:  "echo \(message)"
-	}
-}
-
-command baddisplay: {
-	task display: {
-		kind: "print"
-		text: 42
-	}
-}
-
-command http: {
-	task testserver: {
-		kind: "testserver"
-		url:  string
-	}
-	task http: {
-		kind:   "http"
-		method: "POST"
-		url:    task.testserver.url
-
-		request body:  "I'll be back!"
-		response body: string // TODO: allow this to be a struct, parsing the body.
-	}
-	task print: {
-		kind: "print"
-		text: task.http.response.body
-	}
-}
-
-command print: {
-	task: {
-		t1: exec.Run & {
-			cmd: ["sh", "-c", "sleep 1; echo t1"]
-			stdout: string
-		}
-		t2: exec.Run & {
-			cmd: ["sh", "-c", "sleep 1; echo t2"]
-			stdout: string
-		}
-		t3: cli.Print & {
-			text: (f & {arg: t1.stdout + t2.stdout}).result
-		}
-	}
-}
-
-f :: {
-    arg: string
-    result: strings.Join(strings.Split(arg, ""), ".")
-}
\ No newline at end of file
diff --git a/cmd/cue/cmd/testdata/trim/trim.cue b/cmd/cue/cmd/testdata/trim/trim.cue
deleted file mode 100644
index e5d5da2..0000000
--- a/cmd/cue/cmd/testdata/trim/trim.cue
+++ /dev/null
@@ -1,56 +0,0 @@
-package trim
-
-foo <Name>: {
-	_value: string
-
-	a: 4
-	b: string
-	d: 8
-	e: "foo"
-	f: ">> \( _value) <<"
-	n: 5
-
-	list: ["foo", 8.0]
-
-	struct: {a: 3.0}
-
-	sList: [{a: 8, b: string}, {a: 9, b: *"foo" | string}]
-	rList: [{a: "a"}]
-	rcList: [{a: "a", c: b}]
-
-	t <Name>: {
-		x: >=0 & <=5
-	}
-}
-
-foo bar: {
-	_value: "here"
-	b:      "foo"
-	c:      45
-
-	sList: [{b: "foo"}, {}]
-}
-
-foo baz: {}
-
-foo multipath: {
-	t <Name>: {
-		// Combined with the other template, we know the value must be 5 and
-		// thus the entry below can be eliminated.
-		x: >=5 & <=8
-	}
-
-	t u: {
-	}
-}
-
-// TODO: top-level fields are currently not removed.
-group: {
-	for k, v in foo {
-		comp "\(k)": v
-	}
-
-	comp bar: {
-		aa: 8 // new value
-	}
-}
diff --git a/cmd/cue/cmd/testdata/trim/trim.out b/cmd/cue/cmd/testdata/trim/trim.out
deleted file mode 100644
index e5d5da2..0000000
--- a/cmd/cue/cmd/testdata/trim/trim.out
+++ /dev/null
@@ -1,56 +0,0 @@
-package trim
-
-foo <Name>: {
-	_value: string
-
-	a: 4
-	b: string
-	d: 8
-	e: "foo"
-	f: ">> \( _value) <<"
-	n: 5
-
-	list: ["foo", 8.0]
-
-	struct: {a: 3.0}
-
-	sList: [{a: 8, b: string}, {a: 9, b: *"foo" | string}]
-	rList: [{a: "a"}]
-	rcList: [{a: "a", c: b}]
-
-	t <Name>: {
-		x: >=0 & <=5
-	}
-}
-
-foo bar: {
-	_value: "here"
-	b:      "foo"
-	c:      45
-
-	sList: [{b: "foo"}, {}]
-}
-
-foo baz: {}
-
-foo multipath: {
-	t <Name>: {
-		// Combined with the other template, we know the value must be 5 and
-		// thus the entry below can be eliminated.
-		x: >=5 & <=8
-	}
-
-	t u: {
-	}
-}
-
-// TODO: top-level fields are currently not removed.
-group: {
-	for k, v in foo {
-		comp "\(k)": v
-	}
-
-	comp bar: {
-		aa: 8 // new value
-	}
-}
diff --git a/cmd/cue/cmd/testdata/vet/data.yaml b/cmd/cue/cmd/testdata/vet/data.yaml
deleted file mode 100644
index 1d53144..0000000
--- a/cmd/cue/cmd/testdata/vet/data.yaml
+++ /dev/null
@@ -1,20 +0,0 @@
-# translated messages
-translations:
-  hello:
-    lang: gsw
-    text: Grüetzi
----
-translations:
-  hello:
-    text: Hoi
----
-translations:
-  hello:
-    lang: no
-    text: Hallo
----
-translations:
-  hello:
-    lang: nl
-    text: Hallo
-skip: true
diff --git a/cmd/cue/cmd/testdata/vet/vet.cue b/cmd/cue/cmd/testdata/vet/vet.cue
deleted file mode 100644
index 8bffdf0..0000000
--- a/cmd/cue/cmd/testdata/vet/vet.cue
+++ /dev/null
@@ -1,6 +0,0 @@
-
-translations <_> lang: string
-
-File :: {
-	translations: {...}
-}
diff --git a/cmd/cue/cmd/testdata/vet/vet_expr.out b/cmd/cue/cmd/testdata/vet/vet_expr.out
deleted file mode 100644
index 82323b8..0000000
--- a/cmd/cue/cmd/testdata/vet/vet_expr.out
+++ /dev/null
@@ -1,2 +0,0 @@
-field "skip" not allowed in closed struct:
-    ./testdata/vet/vet.cue:4:9
diff --git a/cmd/cue/cmd/testdata/vet/vet_file.out b/cmd/cue/cmd/testdata/vet/vet_file.out
deleted file mode 100644
index 8d8a23d..0000000
--- a/cmd/cue/cmd/testdata/vet/vet_file.out
+++ /dev/null
@@ -1,5 +0,0 @@
-translations.hello.lang: incomplete value (string):
-    ./testdata/vet/vet.cue:2:24
-translations.hello.lang: conflicting values false and string (mismatched types bool and string):
-    ./testdata/vet/data.yaml:13:11
-    ./testdata/vet/vet.cue:2:24
diff --git a/cmd/cue/cmd/trim_test.go b/cmd/cue/cmd/trim_test.go
deleted file mode 100644
index 6326f31..0000000
--- a/cmd/cue/cmd/trim_test.go
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2018 The CUE Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package cmd
-
-import (
-	"testing"
-)
-
-func TestTrim(t *testing.T) {
-	cmd := newTrimCmd(newRootCmd())
-	mustParseFlags(t, cmd, "-o", "-")
-	runCommand(t, cmd, "trim")
-}
diff --git a/cmd/cue/cmd/vet_test.go b/cmd/cue/cmd/vet_test.go
deleted file mode 100644
index 6856daa..0000000
--- a/cmd/cue/cmd/vet_test.go
+++ /dev/null
@@ -1,33 +0,0 @@
-// Copyright 2019 CUE Authors
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package cmd
-
-import "testing"
-
-func TestVet(t *testing.T) {
-	runCommand(t, newVetCmd(newRootCmd()), "vet")
-
-	cmd := newVetCmd(newRootCmd())
-	mustParseFlags(t, cmd, "-c")
-	runCommand(t, cmd, "vet_conc")
-
-	cmd = newVetCmd(newRootCmd())
-	runCommand(t, cmd, "vet_file", "./testdata/vet/vet.cue", "./testdata/vet/data.yaml")
-
-	cmd = newVetCmd(newRootCmd())
-	mustParseFlags(t, cmd, "-e", "File")
-	runCommand(t, cmd, "vet_expr", "./testdata/vet/vet.cue", "./testdata/vet/data.yaml")
-
-}
diff --git a/cmd/cue/main.go b/cmd/cue/main.go
index 77c34bb..643dfbd 100644
--- a/cmd/cue/main.go
+++ b/cmd/cue/main.go
@@ -15,19 +15,11 @@
 package main
 
 import (
-	"context"
-	"fmt"
 	"os"
 
 	"cuelang.org/go/cmd/cue/cmd"
 )
 
 func main() {
-	err := cmd.Main(context.Background(), os.Args[1:])
-	if err != nil {
-		if err != cmd.ErrPrintedError {
-			fmt.Println(err)
-		}
-		os.Exit(1)
-	}
+	os.Exit(cmd.Main())
 }
diff --git a/go.mod b/go.mod
index 0b23e5c..68b2e98 100644
--- a/go.mod
+++ b/go.mod
@@ -14,6 +14,7 @@
 	github.com/mpvl/unique v0.0.0-20150818121801-cbe035fff7de
 	github.com/pkg/errors v0.8.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/rogpeppe/testscript v1.1.0
 	github.com/spf13/cobra v0.0.3
 	github.com/spf13/pflag v1.0.3
 	github.com/stretchr/testify v1.2.0
diff --git a/go.sum b/go.sum
index e3af646..6cc3c30 100644
--- a/go.sum
+++ b/go.sum
@@ -29,6 +29,8 @@
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rogpeppe/testscript v1.1.0 h1:NxTsoOBQ1zibxf6NDtzrjPbK56hDAteIcOTSINZHtow=
+github.com/rogpeppe/testscript v1.1.0/go.mod h1:lzMlnW8LS56mcdJoQYkrlzqOoTFCOemzt5LusJ93bDM=
 github.com/spf13/cobra v0.0.3 h1:ZlrZ4XsMRm04Fr5pSFxBgfND2EBVa1nLpiy1stUsX/8=
 github.com/spf13/cobra v0.0.3/go.mod h1:1l0Ry5zgKvJasoi3XT1TypsSe7PqH0Sj9dhYf7v3XqQ=
 github.com/spf13/pflag v1.0.3 h1:zPAT6CGy6wXeQ7NtTnaTerfKOsV6V6F8agHXFiazDkg=
@@ -51,5 +53,9 @@
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/errgo.v2 v2.1.0 h1:0vLT13EuvQ0hNvakwLuFZ/jYrLp5F3kcWHXdRggjCE8=
+gopkg.in/errgo.v2 v2.1.0/go.mod h1:hNsd1EY+bozCKY1Ytp96fpM3vjJbqLJn88ws8XvfDNI=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=