Add test app (#12)

tests/test_app.py

@@ -0,0 +1,20 @@
+import pytest
+
+from wagtail_translate.apps import patch_needed
+
+
+@pytest.mark.parametrize(
+    "version, expected",
+    [
+        ((5, 1, 0), True),
+        ((5, 2, 0), True),
+        ((5, 3, 0), True),
+        ((6, 1, 0), True),
+        ((6, 1, 9), True),
+        ((6, 2, 0), False),  # 6.2 introduces the `copy_for_translation_done` signal.
+        ((6, 2, 1), False),
+        ((6, 3, 0), False),
+    ],
+)
+def test_patch_needed(version, expected):
+    assert patch_needed(version) is expected