Properly compute the padding by fixing the ansi escape regexp

internal/util/util.go

@@ -23,12 +23,15 @@ func Fatal(err error) {
 	os.Exit(1)
 }
 
-// Finds the control character sequences (like colors)
-var ctrlFinder = regexp.MustCompile("\x1b\x5b[0-9]+\x6d")
+// Finds the ansi escape sequences (like colors)
+// Taken from: https://github.com/chalk/ansi-regex/blob/d9d806ecb45d899cf43408906a4440060c5c50e5/index.js
+var ansiEscapes = regexp.MustCompile(`[\x1B\x9B][[\]()#;?]*` +
+	`(?:(?:(?:[a-zA-Z\d]*(?:;[a-zA-Z\\d]*)*)?\x07)` +
+	`|(?:(?:\d{1,4}(?:;\d{0,4})*)?[\dA-PRZcf-ntqry=><~]))`)
 
 func EscapeAwareRuneCountInString(s string) int {
 	n := utf8.RuneCountInString(s)
-	for _, sm := range ctrlFinder.FindAllString(s, -1) {
+	for _, sm := range ansiEscapes.FindAllString(s, -1) {
 		n -= utf8.RuneCountInString(sm)
 	}
 	return n

internal/util/util_test.go

@@ -0,0 +1,19 @@
+package util
+
+import (
+	"testing"
+
+	"github.com/fatih/color"
+	ocolor "github.com/ooni/probe-cli/internal/colors"
+)
+
+func TestEscapeAwareRuneCountInString(t *testing.T) {
+	var bold = color.New(color.Bold)
+	var myColor = color.New(color.FgBlue)
+
+	s := myColor.Sprintf("•ABC%s%s", bold.Sprintf("DEF"), ocolor.Red("GHI"))
+	count := EscapeAwareRuneCountInString(s)
+	if count != 10 {
+		t.Errorf("Count was incorrect, got: %d, want: %d.", count, 10)
+	}
+}