test: Add COALESCE + IS NOT NULL join pushdown smoke test

Author: mcheshkov

packages/cubejs-testing/test/__snapshots__/smoke-cubesql.test.ts.snap

@@ -70,6 +70,19 @@ Array [
 ]
 `;
 
+exports[`SQL API Postgres (Data) join with grouped query on coalesce: join grouped on coalesce 1`] = `
+Array [
+  Object {
+    "count": "2",
+    "status": "processed",
+  },
+  Object {
+    "count": "1",
+    "status": "shipped",
+  },
+]
+`;
+
 exports[`SQL API Postgres (Data) join with grouped query: join grouped 1`] = `
 Array [
   Object {

packages/cubejs-testing/test/smoke-cubesql.test.ts

@@ -535,6 +535,36 @@ filter_subq AS (
       expect(res.rows).toMatchSnapshot('join grouped with filter');
     });
 
+    test('join with grouped query on coalesce', async () => {
+      const query = `
+        SELECT
+          "Orders".status AS status,
+          COUNT(*) AS count
+        FROM
+          "Orders"
+          INNER JOIN
+          (
+            SELECT
+              status,
+              SUM(totalAmount)
+            FROM
+              "Orders"
+            GROUP BY 1
+            ORDER BY 2 DESC
+            LIMIT 2
+          ) top_orders
+        ON
+          (COALESCE("Orders".status, '') = COALESCE(top_orders.status, '')) AND
+          (("Orders".status IS NOT NULL) = (top_orders.status IS NOT NULL))
+        GROUP BY 1
+        ORDER BY 1
+        `;
+
+      const res = await connection.query(query);
+      // Expect only top statuses 2 by total amount: processed and shipped
+      expect(res.rows).toMatchSnapshot('join grouped on coalesce');
+    });
+
     test('where segment is false', async () => {
       const query =
         'SELECT value AS val, * FROM "SegmentTest" WHERE segment_eq_1 IS FALSE ORDER BY value;';