Sync implementation

tests/test_database.py

@@ -104,6 +104,28 @@ FEED = feed.Feed(
     ],
 )
 
+OTHER_FEED = feed.Feed(
+    meta=feed.FeedMeta(
+        url="http://example.com/test/other",
+        last_fetched_ts=REF_TIME,
+        retry_after_ts=REF_TIME,
+        status=feed.FEED_STATUS_ALIVE,
+        etag=random_slug(),
+        modified=random_slug(),
+    ),
+    title="Other Test Feed",
+    link="http://example.com/other",
+    entries=[
+        feed.Entry(
+            id=random_slug(),
+            inserted_at=(REF_TIME * 1000) + index,
+            title=f"Entry {index}",
+            link=f"http://example.com/other/a{index}",
+        )
+        for index in range(100, 0, -1)
+    ],
+)
+
 
 def test_database_load_store_meta():
     db = database.Database(":memory:", random_slug())
@@ -274,6 +296,7 @@ def test_database_store_with_older_entries():
     db.store_feed(FEED)
 
     old_entry = FEED.entries[0]
+    assert old_entry.link is not None
 
     older_entry = dataclasses.replace(
         old_entry,
@@ -314,7 +337,7 @@ def test_database_store_update_meta():
     assert db.load_all_meta()[0] == new_meta
 
 
-def test_database_store_update_meta():
+def test_database_store_update_meta_clock():
     db = database.Database(":memory:", random_slug())
     db.ensure_database_schema()
 
@@ -413,3 +436,51 @@ def test_database_redirect_clock():
     db.redirect_feed(FEED.meta.url, new_url)
 
     assert db.get_clock() != old_clock
+
+
+def test_database_sync_clocks():
+    db = database.Database(":memory:", random_slug())
+    db.ensure_database_schema()
+
+    other_origin = f"other_{random_slug()}"
+
+    other_clock = db.get_sync_clock(other_origin)
+    assert other_clock is None
+
+    db.set_sync_clock(other_origin, 1234)
+
+    other_clock = db.get_sync_clock(other_origin)
+    assert other_clock == 1234
+
+
+def test_database_do_sync():
+    db = database.Database(":memory:", random_slug())
+    db.ensure_database_schema()
+
+    other = database.Database(":memory:", random_slug())
+    other.ensure_database_schema()
+
+    other.store_feed(FEED)
+    other.store_feed(OTHER_FEED)
+
+    db.sync_from(other)
+
+    others = db.load_all(feed_limit=99999)
+    assert others == [FEED, OTHER_FEED]
+
+
+def test_database_do_sync_conflict():
+    db = database.Database(":memory:", random_slug())
+    db.ensure_database_schema()
+
+    other = database.Database(":memory:", random_slug())
+    other.ensure_database_schema()
+
+    db.store_feed(FEED)
+    other.store_feed(FEED)
+    other.store_feed(OTHER_FEED)
+
+    db.sync_from(other)
+
+    feeds = db.load_all(feed_limit=99999)
+    assert feeds == [FEED, OTHER_FEED]