chore: add snapshot test for exists subquery

ibis/backends/tests/sql/snapshots/test_select_sql/test_exists_subquery/out.sql

@@ -0,0 +1,15 @@
+SELECT
+  t0.key1 AS key1,
+  t0.key2 AS key2,
+  t0.value1 AS value1
+FROM t1 AS t0
+WHERE
+  EXISTS(
+    (
+      SELECT
+        CAST(1 AS TINYINT) AS "1"
+      FROM t2 AS t1
+      WHERE
+        t0.key1 = t1.key1
+    )
+  )

ibis/backends/tests/sql/test_select_sql.py

@@ -417,15 +417,14 @@ def test_scalar_subquery_different_table(foo, bar, snapshot):
     snapshot.assert_match(to_sql(expr), "out.sql")
 
 
-# TODO(kszucs): should do snapshot testing instead
-# def test_exists_subquery_repr(t1, t2):
-#     # GH #660
+def test_exists_subquery(t1, t2, snapshot):
+    # GH #660
 
-#     cond = t1.key1 == t2.key1
-#     expr = t1[cond.any()]
-#     stmt = get_query(expr)
+    cond = t1.key1 == t2.key1
+    expr = t1[cond.any()]
 
-#     repr(stmt.where[0])
+    snapshot.assert_match(to_sql(expr), "out.sql")
+    assert repr(expr)
 
 
 def test_filter_inside_exists(snapshot):