Implement stringutils.Ellipsis()

This patch implements an Ellipsis utility to
append an ellipsis (...)  when truncating
strings in output.

It also fixes the existing Truncate() utility
to be compatible with unicode/multibyte characters.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Upstream-commit: 51dc35cf23a5418e93128854bedc2e59d8ca743a
Component: engine

components/engine/pkg/stringutils/stringutils.go

@@ -32,12 +32,26 @@ func GenerateRandomASCIIString(n int) string {
 	return string(res)
 }
 
-// Truncate truncates a string to maxlen.
-func Truncate(s string, maxlen int) string {
-	if len(s) <= maxlen {
+// Ellipsis truncates a string to fit within maxlen, and appends ellipsis (...).
+// For maxlen of 3 and lower, no ellipsis is appended.
+func Ellipsis(s string, maxlen int) string {
+	r := []rune(s)
+	if len(r) <= maxlen {
 		return s
 	}
-	return s[:maxlen]
+	if maxlen <= 3 {
+		return string(r[:maxlen])
+	}
+	return string(r[:maxlen-3]) + "..."
+}
+
+// Truncate truncates a string to maxlen.
+func Truncate(s string, maxlen int) string {
+	r := []rune(s)
+	if len(r) <= maxlen {
+		return s
+	}
+	return string(r[:maxlen])
 }
 
 // InSlice tests whether a string is contained in a slice of strings or not.

components/engine/pkg/stringutils/stringutils_test.go

@@ -57,24 +57,40 @@ func TestGenerateRandomAsciiStringIsAscii(t *testing.T) {
 	}
 }
 
+func TestEllipsis(t *testing.T) {
+	str := "t🐳ststring"
+	newstr := Ellipsis(str, 3)
+	if newstr != "t🐳s" {
+		t.Fatalf("Expected t🐳s, got %s", newstr)
+	}
+	newstr = Ellipsis(str, 8)
+	if newstr != "t🐳sts..." {
+		t.Fatalf("Expected tests..., got %s", newstr)
+	}
+	newstr = Ellipsis(str, 20)
+	if newstr != "t🐳ststring" {
+		t.Fatalf("Expected t🐳ststring, got %s", newstr)
+	}
+}
+
 func TestTruncate(t *testing.T) {
-	str := "teststring"
+	str := "t🐳ststring"
 	newstr := Truncate(str, 4)
-	if newstr != "test" {
-		t.Fatalf("Expected test, got %s", newstr)
+	if newstr != "t🐳st" {
+		t.Fatalf("Expected t🐳st, got %s", newstr)
 	}
 	newstr = Truncate(str, 20)
-	if newstr != "teststring" {
-		t.Fatalf("Expected teststring, got %s", newstr)
+	if newstr != "t🐳ststring" {
+		t.Fatalf("Expected t🐳ststring, got %s", newstr)
 	}
 }
 
 func TestInSlice(t *testing.T) {
-	slice := []string{"test", "in", "slice"}
+	slice := []string{"t🐳st", "in", "slice"}
 
-	test := InSlice(slice, "test")
+	test := InSlice(slice, "t🐳st")
 	if !test {
-		t.Fatalf("Expected string test to be in slice")
+		t.Fatalf("Expected string t🐳st to be in slice")
 	}
 	test = InSlice(slice, "SLICE")
 	if !test {