Add frontend tests for concat_ws

src/frontend/test_runner/tests/testdata/expr.yaml

@@ -215,3 +215,29 @@
     create table t (v1 int);
     select coalesce(1,'a') from t;
   binder_error: 'Bind error: types Int32 and Varchar cannot be matched'
+- sql: |
+    create table t (v1 varchar);
+    select concat_ws(v1, 1) as expr from t;
+  batch_plan: |
+    BatchExchange { order: [], dist: Single }
+      BatchProject { exprs: [ConcatWs($0, 1:Int32::Varchar)] }
+        BatchScan { table: t, columns: [v1] }
+  stream_plan: |
+    StreamMaterialize { columns: [expr, _row_id#0(hidden)], pk_columns: [_row_id#0] }
+      StreamProject { exprs: [ConcatWs($0, 1:Int32::Varchar), $1] }
+        StreamTableScan { table: t, columns: [v1, _row_id#0], pk_indices: [1] }
+- sql: |
+    create table t (v1 varchar);
+    select concat_ws(v1, 1.2) from t;
+  batch_plan: |
+    BatchExchange { order: [], dist: Single }
+      BatchProject { exprs: [ConcatWs($0, 1.2:Decimal::Varchar)] }
+        BatchScan { table: t, columns: [v1] }
+- sql: |
+    create table t (v1 int);
+    select concat_ws(v1, 1.2) from t;
+  binder_error: 'Bind error: ConcatWs function must have text as first argument'
+- sql: |
+    create table t (v1 int);
+    select concat_ws() from t;
+  binder_error: 'Bind error: ConcatWs function must contain at least 2 arguments'