test: add unit test for pkg/merge (#764)

pkg/merge/aggregator/loag_agg_test.go

@@ -0,0 +1,54 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package aggregator
+
+import (
+	"testing"
+)
+
+import (
+	"github.com/arana-db/parser"
+
+	"github.com/stretchr/testify/assert"
+)
+
+import (
+	rast "github.com/arana-db/arana/pkg/runtime/ast"
+)
+
+func TestLoadAgg(t *testing.T) {
+	sql := "select max(age), min(age), sum(age), count(age) from student group by name"
+	parser := parser.New()
+	stmt, err := parser.ParseOneStmt(sql, "", "")
+	assert.NoError(t, err)
+
+	rstmt, err := rast.FromStmtNode(stmt)
+	assert.NoError(t, err)
+
+	aggs := LoadAggs(rstmt.(*rast.SelectStatement).Select)
+	assert.Equal(t, 4, len(aggs))
+
+	_, ok := aggs[0]().(*MaxAggregator)
+	assert.True(t, ok)
+	_, ok = aggs[1]().(*MinAggregator)
+	assert.True(t, ok)
+	_, ok = aggs[2]().(*AddAggregator)
+	assert.True(t, ok)
+	_, ok = aggs[3]().(*AddAggregator)
+	assert.True(t, ok)
+}