Add basic test for writes to overlay table without PKs

splitgraph/hooks/data_source/base.py

@@ -396,14 +396,11 @@ def init_write_overlay(
     AS $$
 BEGIN
     IF OLD IS NOT NULL AND NEW IS NULL THEN
-        -- Delete
         INSERT INTO {0}.{2} VALUES (OLD.*, FALSE);
     ELSIF OLD IS NOT NULL AND NEW IS NOT NULL THEN
-        -- Update
         INSERT INTO {0}.{2} VALUES (OLD.*, FALSE);
         INSERT INTO {0}.{2} VALUES (NEW.*, TRUE);
-    ELSE
-        -- Insert
+    ELSIF OLD IS NULL AND NEW IS NOT NULL THEN
         INSERT INTO {0}.{2} VALUES (NEW.*, TRUE);
     END IF;
 

test/splitgraph/commands/test_writable_lq.py

@@ -0,0 +1,57 @@
+from psycopg2.sql import SQL, Identifier
+
+from splitgraph.hooks.data_source.base import WRITE_LOWER_PREFIX, WRITE_UPPER_PREFIX
+
+
+def test_basic_writes_no_pks(pg_repo_local):
+    table_name = "fruits"
+    pg_repo_local.head.checkout(layered=True)
+
+    # Ensure that the table is now in the overlay/LQ mode
+    assert pg_repo_local.is_overlay_view(table_name)
+
+    # Perform some basic writes
+
+    # Insert a couple of new rows
+    pg_repo_local.run_sql("INSERT INTO fruits VALUES (3, 'banana')")
+    pg_repo_local.run_sql("INSERT INTO fruits VALUES (4, 'pear')")
+
+    # Update a row existing in the lower table, and one existing only in the upper (due to insert above)
+    pg_repo_local.run_sql("UPDATE fruits SET name = 'mango' WHERE name = 'orange'")
+    pg_repo_local.run_sql("UPDATE fruits SET name = 'watermelon' WHERE name = 'pear'")
+
+    # Delete a row existing in the lower table, and one existing only in the upper (due to insert/update above)
+    pg_repo_local.run_sql("DELETE FROM fruits WHERE fruit_id = 1")
+    pg_repo_local.run_sql("DELETE FROM fruits WHERE name = 'watermelon'")
+
+    # Won't affect the output of the view due to no PKs on the table
+    pg_repo_local.run_sql("INSERT INTO fruits VALUES (3, 'banana')")
+
+    # Assert the lower table has the old values intact
+    assert pg_repo_local.run_sql(
+        SQL("SELECT * FROM {}").format(Identifier(WRITE_LOWER_PREFIX + table_name))
+    ) == [
+        (1, "apple"),
+        (2, "orange"),
+    ]
+
+    # Assert the upper table stores the pending writes
+    assert pg_repo_local.run_sql(
+        SQL("SELECT * FROM {}").format(Identifier(WRITE_UPPER_PREFIX + table_name))
+    ) == [
+        (3, "banana", True, 1),
+        (4, "pear", True, 2),
+        (2, "orange", False, 3),
+        (2, "mango", True, 4),
+        (4, "pear", False, 5),
+        (4, "watermelon", True, 6),
+        (1, "apple", False, 7),
+        (4, "watermelon", False, 8),
+        (3, "banana", True, 9),
+    ]
+
+    # Assert the correct result from the overlay view
+    assert pg_repo_local.run_sql("SELECT * FROM fruits") == [
+        (2, "mango"),
+        (3, "banana"),
+    ]