Fix duplicate members when filtering for group

https://community.openproject.org/wp/45331

app/models/queries/members/filters/group_filter.rb

@@ -34,7 +34,7 @@ class Queries::Members::Filters::GroupFilter < Queries::Members::Filters::Member
   end
 
   def scope
-    scope = model.joins(:principal).merge(User.joins(:groups))
+    scope = model.joins(:principal)
     scope.where(where)
   end
 end

spec/models/queries/members/filters/group_filter_spec.rb

@@ -54,7 +54,7 @@ describe Queries::Members::Filters::GroupFilter, type: :model do
   end
 
   it_behaves_like 'list_optional group query filter' do
-    let(:model) { Member.joins(:principal).merge(User.joins(:groups)) }
+    let(:model) { Member.joins(:principal) }
     let(:valid_values) { [group1.id.to_s] }
   end
 end

spec/models/queries/members/members_query_integration_spec.rb

@@ -0,0 +1,53 @@
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) 2012-2022 the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+require 'spec_helper'
+
+describe Queries::Members::MemberQuery, 'Integration', type: :model do
+  let(:instance) { described_class.new }
+
+  current_user { user }
+
+  subject { instance.results }
+
+  context 'with two groups in a project' do
+    let(:project) { create(:project) }
+    let(:user) { create(:user) }
+    let(:role) { create(:role, permissions: %i[view_members manage_members]) }
+    let!(:group1) { create(:group, name: 'A', member_in_project: project, member_through_role: role, members: [user]) }
+    let!(:group2) { create(:group, name: 'B', member_in_project: project, member_through_role: role, members: [user]) }
+
+    it 'only returns one user when filtering for one group (Regression #45331)' do
+      instance.where 'project_id', '=', [project.id.to_s]
+      instance.where 'group', '=', [group1.id.to_s]
+
+      expect(subject.count).to eq 1
+      expect(subject.first.user_id).to eq user.id
+    end
+  end
+end