From fb653292612eddca5b088ed88466c546d1597107 Mon Sep 17 00:00:00 2001
From: Elizabeth Alexander Hunt <me@liz.coffee>
Date: Sat, 20 Jun 2026 09:40:07 -0700
Subject: Initial commit

---
 api/canvas/canvas_test.go | 83 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 api/canvas/canvas_test.go

(limited to 'api/canvas/canvas_test.go')

diff --git a/api/canvas/canvas_test.go b/api/canvas/canvas_test.go
new file mode 100644
index 0000000..324a3a1
--- /dev/null
+++ b/api/canvas/canvas_test.go
@@ -0,0 +1,83 @@
+package canvas
+
+import (
+	"database/sql"
+	"path/filepath"
+	"testing"
+
+	"penguins.lan/database"
+)
+
+func canvasTestDB(t *testing.T) *sql.DB {
+	db, err := sql.Open("sqlite3", filepath.Join(t.TempDir(), "c.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { db.Close() })
+	if _, err := database.Migrate(db); err != nil {
+		t.Fatal(err)
+	}
+	return db
+}
+
+func pixelAt(buf []byte, x, y int) int {
+	i := (y*Cols + x) * 3
+	return int(buf[i])<<16 | int(buf[i+1])<<8 | int(buf[i+2])
+}
+
+func TestCurrentCanvasReplaysPixels(t *testing.T) {
+	db := canvasTestDB(t)
+
+	if _, err := database.SavePixel(db, "u", 1, 2, 0xe50000); err != nil {
+		t.Fatal(err)
+	}
+
+	buf, err := currentCanvas(db)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := pixelAt(buf, 1, 2); got != 0xe50000 {
+		t.Errorf("placed pixel = %06x, want e50000", got)
+	}
+	if got := pixelAt(buf, 0, 0); got != defaultColor {
+		t.Errorf("untouched pixel = %06x, want white", got)
+	}
+}
+
+func TestSnapshotBakesThenReplays(t *testing.T) {
+	db := canvasTestDB(t)
+
+	if _, err := database.SavePixel(db, "u", 5, 5, 0x000000); err != nil {
+		t.Fatal(err)
+	}
+	if err := takeSnapshot(db); err != nil {
+		t.Fatal(err)
+	}
+	// a placement after the snapshot must be replayed on top of it
+	if _, err := database.SavePixel(db, "u", 6, 6, 0x02be01); err != nil {
+		t.Fatal(err)
+	}
+
+	buf, err := currentCanvas(db)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := pixelAt(buf, 5, 5); got != 0x000000 {
+		t.Errorf("baked pixel = %06x, want black", got)
+	}
+	if got := pixelAt(buf, 6, 6); got != 0x02be01 {
+		t.Errorf("replayed pixel = %06x, want green", got)
+	}
+
+	// snapshots are kept to one row
+	if err := takeSnapshot(db); err != nil {
+		t.Fatal(err)
+	}
+	var n int
+	if err := db.QueryRow("SELECT COUNT(*) FROM canvas_snapshots").Scan(&n); err != nil {
+		t.Fatal(err)
+	}
+	if n != 1 {
+		t.Errorf("snapshot rows = %d, want 1", n)
+	}
+}
-- 
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