diff --git a/pkg/flatten/flatten_test.go b/pkg/flatten/flatten_test.go
new file mode 100644
index 000000000..5a647f2e9
--- /dev/null
+++ b/pkg/flatten/flatten_test.go
@@ -0,0 +1,33 @@
+package flatten
+
+import (
+	"github.com/icinga/icingadb/pkg/types"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestFlatten(t *testing.T) {
+	for _, st := range []struct {
+		name   string
+		prefix string
+		value  any
+		output map[string]types.String
+	}{
+		{"nil", "a", nil, map[string]types.String{"a": types.NewString("null")}},
+		{"bool", "b", true, map[string]types.String{"b": types.NewString("true")}},
+		{"int", "c", 42, map[string]types.String{"c": types.NewString("42")}},
+		{"float", "d", 77.7, map[string]types.String{"d": types.NewString("77.7")}},
+		{"large_float", "e", 1e23, map[string]types.String{"e": types.NewString("100000000000000000000000")}},
+		{"string", "f", "\x00", map[string]types.String{"f": types.NewString("\x00")}},
+		{"nil_slice", "g", []any(nil), map[string]types.String{"g": {}}},
+		{"empty_slice", "h", []any{}, map[string]types.String{"h": {}}},
+		{"slice", "i", []any{nil}, map[string]types.String{"i[0]": types.NewString("null")}},
+		{"nil_map", "j", map[string]any(nil), map[string]types.String{"j": {}}},
+		{"empty_map", "k", map[string]any{}, map[string]types.String{"k": {}}},
+		{"map", "l", map[string]any{" ": nil}, map[string]types.String{"l. ": types.NewString("null")}},
+	} {
+		t.Run(st.name, func(t *testing.T) {
+			assert.Equal(t, st.output, Flatten(st.value, st.prefix))
+		})
+	}
+}