lib/timeutil: add test for ParseDuration

See https://github.com/VictoriaMetrics/VictoriaMetrics/pull/8403#discussion_r1976110052

Signed-off-by: hagen1778 <roman@victoriametrics.com>

lib/timeutil/duration_test.go

@@ -0,0 +1,29 @@
+package timeutil
+
+import (
+	"testing"
+	"time"
+)
+
+func TestParseDuration(t *testing.T) {
+	f := func(s string, resultExpected time.Duration) {
+		t.Helper()
+		result, err := ParseDuration(s)
+		if err != nil {
+			t.Fatalf("unexpected error: %s", err)
+		}
+		if result != resultExpected {
+			t.Fatalf("unexpected result; got %v; want %v", result, resultExpected)
+		}
+	}
+
+	f("0", 0)
+	f("1s", time.Second)
+	f("1m", time.Minute)
+	f("1h", time.Hour)
+	f("1d", time.Hour*24)
+	f("1w", time.Hour*24*7)
+	f("1m30s", time.Minute+time.Second*30)
+	f("-1m30s", -(time.Minute + time.Second*30))
+	f("1d-4h", time.Hour*20)
+}