Other: Safer user types

internal/safe/slice_test.go

@@ -0,0 +1,34 @@
+package safe
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSlice(t *testing.T) {
+	s := NewSlice(1, 2, 3, 4, 5)
+
+	{
+		var have []int
+
+		s.Iter(func(val int) {
+			have = append(have, val)
+		})
+
+		require.Equal(t, []int{1, 2, 3, 4, 5}, have)
+	}
+
+	s.Append(6)
+	s.Delete(3)
+
+	{
+		var have []int
+
+		s.Iter(func(val int) {
+			have = append(have, val)
+		})
+
+		require.Equal(t, []int{1, 2, 4, 5, 6}, have)
+	}
+}