ui: basic map scroller

client/world/renderer_incremental_catchup_limit_test.go

@@ -0,0 +1,38 @@
+package world
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestTakeCatchUpRects_RespectsAreaLimit(t *testing.T) {
+	t.Parallel()
+
+	pending := []RectPx{
+		{X: 0, Y: 0, W: 10, H: 1}, // area 10
+		{X: 0, Y: 1, W: 10, H: 2}, // area 20
+		{X: 0, Y: 3, W: 10, H: 3}, // area 30
+	}
+
+	// Limit 25 => should take first (10) + second (20) would exceed => take only first.
+	sel, rem := takeCatchUpRects(pending, 25)
+	require.Equal(t, []RectPx{{X: 0, Y: 0, W: 10, H: 1}}, sel)
+	require.Equal(t, []RectPx{
+		{X: 0, Y: 1, W: 10, H: 2},
+		{X: 0, Y: 3, W: 10, H: 3},
+	}, rem)
+
+	// Limit 30 => can take first(10) + second(20) exactly.
+	sel, rem = takeCatchUpRects(pending, 30)
+	require.Equal(t, []RectPx{
+		{X: 0, Y: 0, W: 10, H: 1},
+		{X: 0, Y: 1, W: 10, H: 2},
+	}, sel)
+	require.Equal(t, []RectPx{{X: 0, Y: 3, W: 10, H: 3}}, rem)
+
+	// No limit => take all.
+	sel, rem = takeCatchUpRects(pending, 0)
+	require.Len(t, sel, 3)
+	require.Empty(t, rem)
+}