1 files changed, 19 insertions, 0 deletions
diff --git a/layout/math_test.go b/layout/math_test.go
new file mode 100644
index 0000000..7ff6b78
--- /dev/null
+++ b/layout/math_test.go
@@ -0,0 +1,19 @@
+package layout
+
+import "testing"
+
+func TestSum(t *testing.T) {
+	t.Parallel()
+	testSum(t, []int{}, 0)
+	testSum(t, []int{0}, 0)
+	testSum(t, []int{1}, 1)
+	testSum(t, []int{12, 34}, 46)
+	testSum(t, []int{12, 34, 56}, 102)
+}
+
+func testSum[N number](t *testing.T, s []N, want N) {
+	n := sum(s)
+	if n != want {
+		t.Errorf("sum(%v) = %v; want %v", s, n, want)
+	}
+}