test: unit test for util ColumeNameVisitor

@winfredLIN

sqle/driver/mysql/util/visitor_test.go

@@ -105,3 +105,35 @@ func TestSelectFieldExtractor(t *testing.T) {
 		})
 	}
 }
+
+func TestColumeNameVisitor(t *testing.T) {
+	tests := []struct {
+		input       string
+		columnCount uint
+	}{
+		{"SELECT * FROM t1", 0},                                                         //不包含列
+		{"SELECT a,b,c FROM t1 WHERE id > 1", 4},                                        //使用不等号
+		{"SELECT COUNT(*) FROM t1", 0},                                                  //使用函数并不包含列
+		{"SELECT a,COUNT(*) FROM t1 GROUP BY a", 2},                                     //使用函数包含列
+		{"SELECT * FROM table1 INNER JOIN table2 ON table1.id = table2.table1_id", 2},   //使用JOIN
+		{"SELECT * FROM table1 WHERE id IN ( SELECT id FROM table2 WHERE age > 30)", 3}, //使用子查询
+		{"SELECT UPPER(name), LENGTH(comments) FROM table1", 2},                         //使用函数
+		{"SELECT CAST(price AS DECIMAL(10,2))FROM products", 1},                         //使用类型转换
+		{"SELECT * FROM table1 INNER JOIN table2 ON table1.id = table2.table1_id INNER JOIN table3 ON table2.id = table3.table2_id", 4}, //使用JOIN嵌套
+		{"SELECT column1 AS alias1, column2 AS alias2 FROM table1", 2},                                                                  //使用列别名
+		{"SELECT column1 + column2 AS sum_columns FROM table1", 2},
+		{"SELECT t1.column1 AS t1_col1, t2.column2 AS t2_col2 FROM table1 t1 INNER JOIN table2 t2 ON t1.id = t2.t1_id", 4}, //不带AS的表别名
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			stmt, err := parser.New().ParseOneStmt(tt.input, "", "")
+			assert.NoError(t, err)
+
+			visitor := &ColumeNameVisitor{}
+			stmt.Accept(visitor)
+
+			assert.Equal(t, tt.columnCount, uint(len(visitor.ColumeNameList)))
+		})
+	}
+}