fix(query-generator): do not generate GROUP BY clause if options.group is empty (#12343)

lib/dialects/abstract/query-generator.js

@@ -1333,9 +1333,9 @@ class QueryGenerator {
     if (options.group) {
       options.group = Array.isArray(options.group) ? options.group.map(t => this.aliasGrouping(t, model, mainTable.as, options)).join(', ') : this.aliasGrouping(options.group, model, mainTable.as, options);
 
-      if (subQuery) {
+      if (subQuery && options.group) {
         subQueryItems.push(` GROUP BY ${options.group}`);
-      } else {
+      } else if (options.group) {
         mainQueryItems.push(` GROUP BY ${options.group}`);
       }
     }

test/unit/sql/group.test.js

+'use strict';
+
+const Support = require('../support'),
+  DataTypes   = require('../../../lib/data-types'),
+  util        = require('util'),
+  expectsql   = Support.expectsql,
+  current     = Support.sequelize,
+  sql         = current.dialect.queryGenerator;
+
+
+describe(Support.getTestDialectTeaser('SQL'), () => {
+  describe('group', () => {
+    const testsql = function(options, expectation) {
+      const model = options.model;
+
+      it(util.inspect(options, { depth: 2 }), () => {
+        return expectsql(
+          sql.selectQuery(
+            options.table || model && model.getTableName(),
+            options,
+            options.model
+          ),
+          expectation
+        );
+      });
+    };
+
+    const User = Support.sequelize.define('User', {
+      name: {
+        type: DataTypes.STRING,
+        field: 'name',
+        allowNull: false
+      }
+    });
+
+    testsql({
+      model: User,
+      group: ['name']
+    }, {
+      default: 'SELECT * FROM `Users` AS `User` GROUP BY `name`;',
+      postgres: 'SELECT * FROM "Users" AS "User" GROUP BY "name";',
+      mssql: 'SELECT * FROM [Users] AS [User] GROUP BY [name];'
+    });
+
+    testsql({
+      model: User,
+      group: []
+    }, {
+      default: 'SELECT * FROM `Users` AS `User`;',
+      postgres: 'SELECT * FROM "Users" AS "User";',
+      mssql: 'SELECT * FROM [Users] AS [User];'
+    });
+  });
+});