add planner test

Signed-off-by: Runji Wang <[email protected]>

src/frontend/planner_test/tests/testdata/input/expr.yaml

@@ -454,3 +454,15 @@
   expected_outputs:
   - batch_plan
   - stream_error
+- name: without variadic keyword
+  sql: |
+    create table t(a varchar, b varchar);
+    select concat_ws(',', a, b) from t;
+  expected_outputs:
+  - batch_plan
+- name: with variadic keyword
+  sql: |
+    create table t(a varchar, b varchar);
+    select concat_ws(',', variadic array[a, b]) from t;
+  expected_outputs:
+  - batch_plan

src/frontend/planner_test/tests/testdata/output/expr.yaml

@@ -635,3 +635,19 @@
     Not supported: streaming nested-loop join
     HINT: The non-equal join in the query requires a nested-loop join executor, which could be very expensive to run. Consider rewriting the query to use dynamic filter as a substitute if possible.
     See also: https://github.com/risingwavelabs/rfcs/blob/main/rfcs/0033-dynamic-filter.md
+- name: without variadic keyword
+  sql: |
+    create table t(a varchar, b varchar);
+    select concat_ws(',', a, b) from t;
+  batch_plan: |-
+    BatchExchange { order: [], dist: Single }
+    └─BatchProject { exprs: [ConcatWs(',':Varchar, t.a, t.b) as $expr1] }
+      └─BatchScan { table: t, columns: [t.a, t.b], distribution: SomeShard }
+- name: with variadic keyword
+  sql: |
+    create table t(a varchar, b varchar);
+    select concat_ws(',', variadic array[a, b]) from t;
+  batch_plan: |-
+    BatchExchange { order: [], dist: Single }
+    └─BatchProject { exprs: [ConcatWsVariadic(',':Varchar, Array(t.a, t.b)) as $expr1] }
+      └─BatchScan { table: t, columns: [t.a, t.b], distribution: SomeShard }