Consolidate Persimmons shared backend and tests

tests/test_persimmons_update.py

@@ -0,0 +1,40 @@
+import importlib.util
+import io
+import json
+from pathlib import Path
+import tempfile
+import unittest
+import zipfile
+
+ROOT = Path(__file__).resolve().parents[1]
+spec = importlib.util.spec_from_file_location('updater', ROOT / 'persimmons/web/update-extension.py')
+updater = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(updater)
+
+
+class UpdateTests(unittest.TestCase):
+    def test_same_folder_preserves_identity_and_unrelated_files(self):
+        with tempfile.TemporaryDirectory() as name:
+            folder = Path(name)
+            manifest = (ROOT / 'persimmons-extension/manifest.json').read_bytes()
+            (folder / 'manifest.json').write_bytes(manifest)
+            (folder / 'keep.txt').write_text('unrelated')
+            raw = (ROOT / 'persimmons/web/extension.zip').read_bytes()
+            self.assertEqual(updater.update(folder, raw), json.loads(manifest)['version'])
+            self.assertEqual((folder / 'keep.txt').read_text(), 'unrelated')
+            self.assertEqual((folder / 'manifest.json').read_bytes(), manifest)
+            for bad in ('persimmons-extension/../escape.mjs', '/tmp/escape.mjs'):
+                archive = io.BytesIO()
+                with zipfile.ZipFile(archive, 'w') as zipped:
+                    zipped.writestr('persimmons-extension/manifest.json', manifest)
+                    zipped.writestr(bad, 'bad')
+                with self.assertRaises(ValueError):
+                    updater.update(folder, archive.getvalue())
+            archive = io.BytesIO()
+            with zipfile.ZipFile(archive, 'w') as zipped:
+                changed = json.loads(manifest)
+                changed['key'] = 'YWJj'
+                zipped.writestr('persimmons-extension/manifest.json', json.dumps(changed))
+            with self.assertRaises(ValueError):
+                updater.update(folder, archive.getvalue())
+            self.assertEqual((folder / 'manifest.json').read_bytes(), manifest)