A virtual jailed shell environment for Go apps backed by an io/fs#FS.
feat(command): add clear command
Emit the standard ANSI screen-clear sequence (ESC[2J ESC[H) on
stdout. Useful inside the kefka shell where the host terminal's
own clear binary is not available, and matches the behavior users
expect from a coreutils-style clear.
Signed-off-by: Xe Iaso <me@xeiaso.net>
Assisted-by: Claude Opus 4.7 via Claude Code
+146
+56
command/internal/clear/clear.go
+56
command/internal/clear/clear.go
···
1
+
package clear
2
+
3
+
import (
4
+
"context"
5
+
"errors"
6
+
"fmt"
7
+
"io"
8
+
9
+
"github.com/pborman/getopt/v2"
10
+
"mvdan.cc/sh/v3/interp"
11
+
"tangled.org/xeiaso.net/kefka/command"
12
+
)
13
+
14
+
type Impl struct{}
15
+
16
+
func (Impl) Exec(ctx context.Context, ec *command.ExecContext, args []string) error {
17
+
if ec == nil {
18
+
return errors.New("clear: nil ExecContext")
19
+
}
20
+
21
+
stdout := ec.Stdout
22
+
if stdout == nil {
23
+
stdout = io.Discard
24
+
}
25
+
stderr := ec.Stderr
26
+
if stderr == nil {
27
+
stderr = io.Discard
28
+
}
29
+
30
+
set := getopt.New()
31
+
set.SetProgram("clear")
32
+
set.SetParameters("")
33
+
34
+
usage := func() {
35
+
fmt.Fprint(stderr, "Usage: clear [OPTIONS]\n")
36
+
fmt.Fprint(stderr, "Clear the terminal screen.\n\n")
37
+
fmt.Fprint(stderr, " --help display this help and exit\n")
38
+
}
39
+
set.SetUsage(usage)
40
+
41
+
help := set.BoolLong("help", 0, "display this help and exit")
42
+
43
+
if err := set.Getopt(append([]string{"clear"}, args...), nil); err != nil {
44
+
fmt.Fprintf(stderr, "clear: %s\n", err)
45
+
usage()
46
+
return interp.ExitStatus(1)
47
+
}
48
+
49
+
if *help {
50
+
usage()
51
+
return nil
52
+
}
53
+
54
+
io.WriteString(stdout, "\x1b[2J\x1b[H")
55
+
return nil
56
+
}
+88
command/internal/clear/clear_test.go
+88
command/internal/clear/clear_test.go
···
1
+
package clear
2
+
3
+
import (
4
+
"bytes"
5
+
"context"
6
+
"strings"
7
+
"testing"
8
+
9
+
"tangled.org/xeiaso.net/kefka/command"
10
+
)
11
+
12
+
func run(t *testing.T, args []string) (string, string, error) {
13
+
t.Helper()
14
+
var stdout, stderr bytes.Buffer
15
+
ec := &command.ExecContext{
16
+
Stdout: &stdout,
17
+
Stderr: &stderr,
18
+
Dir: ".",
19
+
}
20
+
err := Impl{}.Exec(context.Background(), ec, args)
21
+
return stdout.String(), stderr.String(), err
22
+
}
23
+
24
+
func TestClear(t *testing.T) {
25
+
tests := []struct {
26
+
name string
27
+
args []string
28
+
wantStdout string
29
+
wantErr bool
30
+
}{
31
+
{
32
+
name: "no args writes ANSI clear sequence",
33
+
args: []string{},
34
+
wantStdout: "\x1b[2J\x1b[H",
35
+
},
36
+
{
37
+
name: "extra positional args are ignored",
38
+
args: []string{"foo", "bar"},
39
+
wantStdout: "\x1b[2J\x1b[H",
40
+
},
41
+
{
42
+
name: "unknown flag returns error",
43
+
args: []string{"--no-such-flag"},
44
+
wantErr: true,
45
+
},
46
+
}
47
+
48
+
for _, tt := range tests {
49
+
t.Run(tt.name, func(t *testing.T) {
50
+
stdout, stderr, err := run(t, tt.args)
51
+
if tt.wantErr {
52
+
if err == nil {
53
+
t.Fatalf("expected error, got nil; stdout=%q stderr=%q", stdout, stderr)
54
+
}
55
+
return
56
+
}
57
+
if err != nil {
58
+
t.Fatalf("unexpected error: %v; stderr=%q", err, stderr)
59
+
}
60
+
if stdout != tt.wantStdout {
61
+
t.Errorf("stdout = %q, want %q", stdout, tt.wantStdout)
62
+
}
63
+
})
64
+
}
65
+
}
66
+
67
+
func TestHelp(t *testing.T) {
68
+
stdout, stderr, err := run(t, []string{"--help"})
69
+
if err != nil {
70
+
t.Fatalf("unexpected error: %v", err)
71
+
}
72
+
if stdout != "" {
73
+
t.Errorf("expected empty stdout, got %q", stdout)
74
+
}
75
+
if !strings.Contains(stderr, "Usage: clear [OPTIONS]") {
76
+
t.Errorf("usage line missing from stderr: %q", stderr)
77
+
}
78
+
if !strings.Contains(stderr, "--help") {
79
+
t.Errorf("help flag missing from help text: %q", stderr)
80
+
}
81
+
}
82
+
83
+
func TestNilStdout(t *testing.T) {
84
+
ec := &command.ExecContext{Dir: "."}
85
+
if err := (Impl{}).Exec(context.Background(), ec, nil); err != nil {
86
+
t.Fatalf("unexpected error with nil stdout/stderr: %v", err)
87
+
}
88
+
}
+2
command/registry/coreutils/coreutils.go
+2
command/registry/coreutils/coreutils.go
···
3
3
import (
4
4
"tangled.org/xeiaso.net/kefka/command/internal/base64"
5
5
"tangled.org/xeiaso.net/kefka/command/internal/basename"
6
+
"tangled.org/xeiaso.net/kefka/command/internal/clear"
6
7
"tangled.org/xeiaso.net/kefka/command/internal/falsecmd"
7
8
"tangled.org/xeiaso.net/kefka/command/internal/hostname"
8
9
"tangled.org/xeiaso.net/kefka/command/internal/ls"
···
13
14
func Register(reg *registry.Impl) {
14
15
reg.Register("base64", base64.Impl{})
15
16
reg.Register("basename", basename.Impl{})
17
+
reg.Register("clear", clear.Impl{})
16
18
reg.Register("false", falsecmd.Impl{})
17
19
reg.Register("hostname", hostname.Impl{})
18
20
reg.Register("ls", ls.Impl{})