Prepare Jira users importer

- prepare service classes that will be used later

app/services/jira_import/users_importer.rb

+# frozen_string_literal: true
+
+module JiraImport
+  class UsersImporter
+    attr_reader :user, :project, :start_at, :result
+
+    MAX_USERS = 50
+
+    def initialize(user, project, start_at)
+      @project = project
+      @start_at = start_at
+      @user = user
+    end
+
+    def execute
+      project.validate_jira_import_settings!(user: user)
+
+      return ServiceResponse.success(payload: nil) if users.blank?
+
+      result = UsersMapper.new(project, users).execute
+      ServiceResponse.success(payload: result)
+    rescue Timeout::Error, Errno::EINVAL, Errno::ECONNRESET, Errno::ECONNREFUSED, URI::InvalidURIError, JIRA::HTTPError, OpenSSL::SSL::SSLError => error
+      Gitlab::ErrorTracking.track_exception(error, project_id: project.id, request: url)
+      ServiceResponse.error(message: "There was an error when communicating to Jira: #{error.message}")
+    end
+
+    private
+
+    def users
+      @users ||= client.get(url)
+    end
+
+    def url
+      "/rest/api/2/users?maxResults=#{MAX_USERS}&startAt=#{start_at.to_i}"
+    end
+
+    def client
+      @client ||= project.jira_service.client
+    end
+  end
+end

app/services/jira_import/users_mapper.rb

+# frozen_string_literal: true
+
+module JiraImport
+  class UsersMapper
+    attr_reader :project, :jira_users
+
+    def initialize(project, jira_users)
+      @project = project
+      @jira_users = jira_users
+    end
+
+    def execute
+      jira_users.to_a.map do |jira_user|
+        {
+          jira_account_id: jira_user['accountId'],
+          jira_display_name: jira_user['displayName'],
+          jira_email: jira_user['emailAddress'],
+          gitlab_id: match_user(jira_user)
+        }
+      end
+    end
+
+    private
+
+    # TODO: Matching user by email and displayName will be done as the part
+    # of follow-up issue: https://gitlab.com/gitlab-org/gitlab/-/issues/219023
+    def match_user(jira_user)
+      nil
+    end
+  end
+end

spec/services/jira_import/users_importer_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe JiraImport::UsersImporter do
+  include JiraServiceHelper
+
+  let_it_be(:user) { create(:user) }
+  let_it_be(:project, reload: true) { create(:project) }
+  let_it_be(:start_at) { 7 }
+
+  let(:importer) { described_class.new(user, project, start_at) }
+
+  subject { importer.execute }
+
+  describe '#execute' do
+    before do
+      stub_jira_service_test
+      project.add_maintainer(user)
+    end
+
+    context 'when Jira import is not configured properly' do
+      it 'raises an error' do
+        expect { subject }.to raise_error(Projects::ImportService::Error)
+      end
+    end
+
+    context 'when Jira import is configured correctly' do
+      let_it_be(:jira_service) { create(:jira_service, project: project, active: true) }
+      let(:client) { double }
+
+      before do
+        expect(importer).to receive(:client).and_return(client)
+      end
+
+      context 'when jira client raises an error' do
+        it 'returns an error response' do
+          expect(client).to receive(:get).and_raise(Timeout::Error)
+
+          expect(subject.error?).to be_truthy
+          expect(subject.message).to include('There was an error when communicating to Jira')
+        end
+      end
+
+      context 'when jira client returns result' do
+        before do
+          allow(client).to receive(:get).with('/rest/api/2/users?maxResults=50&startAt=7')
+            .and_return(jira_users)
+        end
+
+        context 'when jira client returns an empty array' do
+          let(:jira_users) { [] }
+
+          it 'retturns nil payload' do
+            expect(subject.success?).to be_truthy
+            expect(subject.payload).to be_nil
+          end
+        end
+
+        context 'when jira client returns an results' do
+          let(:jira_users)   { [{ 'name' => 'user1' }, { 'name' => 'user2' }] }
+          let(:mapped_users) { [{ jira_display_name: 'user1', gitlab_id: 5 }] }
+
+          before do
+            expect(JiraImport::UsersMapper).to receive(:new).with(project, jira_users)
+            .and_return(double(execute: mapped_users))
+          end
+
+          it 'returns the mapped users' do
+            expect(subject.success?).to be_truthy
+            expect(subject.payload).to eq(mapped_users)
+          end
+        end
+      end
+    end
+  end
+end

spec/services/jira_import/users_mapper_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe JiraImport::UsersMapper do
+  let_it_be(:project) { create(:project) }
+
+  subject { described_class.new(project, jira_users).execute }
+
+  describe '#execute' do
+    context 'jira_users is nil' do
+      let(:jira_users) { nil }
+
+      it 'returns an empty array' do
+        expect(subject).to be_empty
+      end
+    end
+
+    context 'when jira_users is present' do
+      let(:jira_users) do
+        [
+          { 'accountId' => 'abcd', 'displayName' => 'user1' },
+          { 'accountId' => 'efg' },
+          { 'accountId' => 'hij', 'displayName' => 'user3', 'emailAddress' => 'user3@example.com' }
+        ]
+      end
+
+      # TODO: now we only create an array in a proper format
+      # mapping is tracked in https://gitlab.com/gitlab-org/gitlab/-/issues/219023
+      let(:mapped_users) do
+        [
+          { jira_account_id: 'abcd', jira_display_name: 'user1', jira_email: nil, gitlab_id: nil },
+          { jira_account_id: 'efg', jira_display_name: nil, jira_email: nil, gitlab_id: nil },
+          { jira_account_id: 'hij', jira_display_name: 'user3', jira_email: 'user3@example.com', gitlab_id: nil }
+        ]
+      end
+
+      it 'returns users mapped to Gitlab' do
+        expect(subject).to eq(mapped_users)
+      end
+    end
+  end
+end