expand docs and explanations

tests/integration_tests/test_all_cache_types.py

@@ -105,11 +105,18 @@ def test_replace_strategy(
     new_generic_cache: ab.caches.CacheBase,
     mocker: pytest.MockerFixture,
 ) -> None:
-    """Test that the append strategy works as expected."""
+    """Test that the replace strategy works as expected.
+
+    We expect old data to be fully replaced with newer data. For this test,
+    we run the 'seed b' test (expected 300 records) before the 'seed a' test
+    (expected 200 records). We assert the correct count of records at each step,
+    first 300 and then 200 records.
+    """
     mocker.spy(new_generic_cache.processor, '_swap_temp_table_with_final_table')
     mocker.spy(new_generic_cache.processor, '_merge_temp_table_to_final_table')
 
-    assert FAKER_SCALE_B > FAKER_SCALE_A
+    assert FAKER_SCALE_B > FAKER_SCALE_A, \
+        "The test requires that 'b' has a greater count of records than 'a'."
 
     result = source_faker_seed_b.read(
         new_generic_cache,