extending abs_path in db and test coverage

tests/test_cachedpage_abs_path.py

@@ -0,0 +1,27 @@
+import os
+from web.db import CachedPage
+from web.utils import get_cache_dir
+
+
+def test_cachedpage_abs_path(tmp_path, monkeypatch):
+    # Create a fake cache dir and monkeypatch get_cache_dir
+    fake_cache = tmp_path / 'cache'
+    fake_cache.mkdir()
+    monkeypatch.setenv('PYTHONIOENCODING', 'utf-8')
+
+    # Patch the symbol used by CachedPage.abs_path (imported into web.db)
+    monkeypatch.setattr('web.db.get_cache_dir', lambda: str(fake_cache))
+
+    # Create a CachedPage instance and set file_path attribute
+    cp = CachedPage()
+    setattr(cp, 'file_path', 'subdir/test.html')
+
+    # Ensure the computed absolute path joins the fake cache dir
+    expected = os.path.join(os.path.abspath(
+        str(fake_cache)), 'subdir/test.html')
+    assert cp.abs_path == expected
+
+    # When file_path is falsy, abs_path should be None
+    cp2 = CachedPage()
+    setattr(cp2, 'file_path', None)
+    assert cp2.abs_path is None