WIP: set up snapshot testing

.gitignore

@@ -1,4 +1,8 @@
 
+# pytest-textual-snapshot
+snapshot_report.html
+
+
 # Temporary backup files from Textual Paint and other editors
 *~
 

cspell.json

@@ -123,6 +123,7 @@
 		"pyperclip",
 		"pypixelart",
 		"pyright",
+		"pytest",
 		"pyxdg",
 		"qualname",
 		"rasterization",

requirements.txt

@@ -12,3 +12,5 @@ textual[dev]==0.28.0
 watchdog==3.0.0 # for development; optional (only used when --restart-on-changes is passed)
 types-Pillow==10.0.0.1 # for development
 types-psutil==5.9.5.15 # for development
+pytest==7.4.1 # for development
+pytest-textual-snapshot==0.4.0 # for development

tests/test_snapshots.py

@@ -0,0 +1,18 @@
+from pathlib import Path
+
+import pytest
+
+# These paths are treated as relative to this file.
+APPS_DIR = Path("../src/textual_paint")
+PAINT = APPS_DIR / "paint.py"
+GALLERY = APPS_DIR / "gallery.py"
+
+def test_paint_app(snap_compare):
+    assert snap_compare(PAINT)
+
+def test_paint_stretch_skew(snap_compare):
+    assert snap_compare(PAINT, press=["ctrl+w"])
+
+def test_gallery_app(snap_compare):
+    assert snap_compare(GALLERY)
+