progress: auto-select progress based on $PS1

This commit adds automatic progress bar selection based on the
environment. Ideally we would check for a terminal but with
podman we never have one. So we check for PS1 and anf if that is
used we assume it's an interactive shell and give the nice
"terminalProgressBar". If that is not set we assuem we run in
a script or CI/CD environment and select plainProgressBar.

bib/internal/progress/progress.go

@@ -68,9 +68,14 @@ type ProgressBar interface {
 // New creates a new progressbar based on the requested type
 func New(typ string) (ProgressBar, error) {
 	switch typ {
-	// XXX: autoseelct based on PS1 value (i.e. use term in
-	// interactive shells only?)
-	case "", "plain":
+	case "":
+		// autoselect based on if we are on an interactive
+		// shell, use plain progress for scripts
+		if _, ok := os.LookupEnv("PS1"); ok {
+			return NewTerminalProgressBar()
+		}
+		return NewPlainProgressBar()
+	case "plain":
 		return NewPlainProgressBar()
 	case "term":
 		return NewTerminalProgressBar()

bib/internal/progress/progress_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"reflect"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -110,3 +111,23 @@ func TestTermProgress(t *testing.T) {
 	// check shutdown
 	assert.Contains(t, buf.String(), progress.CURSOR_SHOW)
 }
+
+func TestProgressNewAutoselect(t *testing.T) {
+	for _, tc := range []struct {
+		env      string
+		expected interface{}
+	}{
+		{"", &progress.PlainProgressBar{}},
+		{"PS1=foo", &progress.TerminalProgressBar{}},
+	} {
+
+		if l := strings.SplitN(tc.env, "=", 2); len(l) == 2 {
+			t.Setenv(l[0], l[1])
+		}
+
+		pb, err := progress.New("")
+		assert.NoError(t, err)
+		assert.Equal(t, reflect.TypeOf(pb), reflect.TypeOf(tc.expected), fmt.Sprintf("[%v] %T not the expected %T", tc.env, pb, tc.expected))
+	}
+
+}