refactor: internal package

internal/stringx/stringx.go

@@ -0,0 +1,33 @@
+// Package stringx provides helper functions for working with strings.
+package stringx
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"regexp"
+)
+
+var compactRE = regexp.MustCompile(`\s+`)
+
+// Shorten shortens a string to a specified number of characters.
+func Shorten(s string, maxlen int) string {
+	var short = []rune(s)
+	if len(short) > maxlen {
+		short = short[:maxlen]
+		short = append(short, []rune(" [truncated]")...)
+	}
+	return string(short)
+}
+
+// Compact replaces consecutive whitespaces with a single space.
+func Compact(s string) string {
+	return compactRE.ReplaceAllString(string(s), " ")
+}
+
+// RandString generates a random string.
+// length must be even.
+func RandString(length int) string {
+	b := make([]byte, length/2)
+	_, _ = rand.Read(b)
+	return hex.EncodeToString(b)
+}

internal/stringx/stringx_test.go

@@ -0,0 +1,51 @@
+package stringx
+
+import "testing"
+
+func TestShorten(t *testing.T) {
+	t.Run("shorten", func(t *testing.T) {
+		const src = "Hello, World!"
+		const want = "Hello [truncated]"
+		got := Shorten(src, 5)
+		if got != want {
+			t.Errorf("expected %q, got %q", got, want)
+		}
+	})
+	t.Run("ignore", func(t *testing.T) {
+		const src = "Hello, World!"
+		const want = src
+		got := Shorten(src, 20)
+		if got != want {
+			t.Errorf("expected %q, got %q", got, want)
+		}
+	})
+}
+
+func TestCompact(t *testing.T) {
+	t.Run("compact", func(t *testing.T) {
+		const src = "go\nis   awesome"
+		const want = "go is awesome"
+		got := Compact(src)
+		if got != want {
+			t.Errorf("expected %q, got %q", got, want)
+		}
+	})
+	t.Run("ignore", func(t *testing.T) {
+		const src = "go is awesome"
+		const want = src
+		got := Compact(src)
+		if got != want {
+			t.Errorf("expected %q, got %q", got, want)
+		}
+	})
+}
+
+func TestRandString(t *testing.T) {
+	lengths := []int{2, 4, 6, 8, 10}
+	for _, n := range lengths {
+		s := RandString(n)
+		if len(s) != n {
+			t.Errorf("%d: expected len(s) = %d, got %d", n, n, len(s))
+		}
+	}
+}