Add a NtpServer class

* Its responsabilities are to determine the default NTP servers
  and to read a list from a YAML file.

src/lib/y2network/ntp_server.rb

@@ -0,0 +1,69 @@
+# Copyright (c) [2020] SUSE LLC
+#
+# All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of version 2 of the GNU General Public License as published
+# by the Free Software Foundation.
+#
+# 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, contact SUSE LLC.
+#
+# To contact SUSE LLC about this file by physical or electronic mail, you may
+# find current contact information at www.suse.com.
+
+require "yast"
+require "yaml"
+
+Yast.import "Product"
+
+module Y2Network
+  class NtpServer
+    attr_reader :hostname
+    attr_reader :country
+
+    class << self
+      # Determines the default servers
+      #
+      # The content of this list depends on the base product.
+      #
+      # @return [Array<NtpServer>] Default NTP servers
+      def default_servers(product = nil)
+        base_products = Yast::Product.FindBaseProducts
+
+        host =
+          if base_products.any? { |p| p["name"] =~ /openSUSE/i }
+            "opensuse"
+          else
+            "suse"
+          end
+
+        (0..3).map { |i| new("#{i}.#{host}.pool.ntp.org") }
+      end
+
+      # Loads the list of servers from the given file
+      #
+      # @param path [String] File path
+      # @return [Array<NtpServer>] Array containing all the servers
+      def load_from_file(path)
+        YAML.load_file(path).map do |server|
+          new(server["address"], country: server["country"])
+        end
+      end
+    end
+
+    # Constructor
+    #
+    # @param hostname [String] NTP server's hostname
+    # @param country  [String] Country code (e.g., "DE")
+    def initialize(hostname, country: nil)
+      @hostname = hostname
+      @country = country
+    end
+  end
+end

test/data/ntp_servers.yml

@@ -0,0 +1,9 @@
+---
+
+- access_policy: open access
+  address: ntp.cgi.cz
+  country: CZ
+  exact_location: Prague, The Czech Republic
+  location: Czech Republic
+  stratum: '2'
+  synchronization: NTP V4 secondary (stratum 2), PC/FreeBSD

test/y2network/ntp_server_test.rb

@@ -0,0 +1,64 @@
+# Copyright (c) [2020] SUSE LLC
+#
+# All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of version 2 of the GNU General Public License as published
+# by the Free Software Foundation.
+#
+# 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, contact SUSE LLC.
+#
+# To contact SUSE LLC about this file by physical or electronic mail, you may
+# find current contact information at www.suse.com.
+
+require_relative "../test_helper"
+
+require "y2network/ntp_server"
+
+describe Y2Network::NtpServer do
+  describe ".default_servers" do
+    before do
+      allow(Yast::Product).to receive(:FindBaseProducts)
+        .and_return(products)
+    end
+
+    context "when running in an openSUSE system" do
+      let(:products) do
+        [{ "name" => "openSUSE" }]
+      end
+
+      it "returns a set of opensuse.pool.ntp.org servers" do
+        domain = "opensuse.pool.ntp.org"
+        expect(described_class.default_servers.map(&:hostname)).to eq([
+          "0.#{domain}", "1.#{domain}", "2.#{domain}", "3.#{domain}"
+        ])
+      end
+    end
+
+    context "when not running in an openSUSE system" do
+      let(:products) do
+        [{ "name" => "SLES" }]
+      end
+
+      it "returns a set of suse.pool.ntp.org servers" do
+        domain = "suse.pool.ntp.org"
+        expect(described_class.default_servers.map(&:hostname)).to eq([
+          "0.#{domain}", "1.#{domain}", "2.#{domain}", "3.#{domain}"
+        ])
+      end
+    end
+  end
+
+  describe "'.load_from_file" do
+    it "returns the list of servers from the file" do
+      servers = described_class.load_from_file(File.join(DATA_PATH, "ntp_servers.yml"))
+      expect(servers.map(&:hostname)).to eq(["ntp.cgi.cz"])
+    end
+  end
+end