Fix alpine networking for public network

Updates the alpine guest network configuration for public network
entry with `use_dhcp_assigned_default_route` to use the `udhcpc`
command instead of the `dhclient` command which is not included.

templates/guests/alpine/network_dhcp.erb

@@ -7,7 +7,7 @@ iface eth<%= options[:interface] %> inet dhcp
 <% else %>
     # We need to disable eth0, see GH-2648
     post-up route del default dev eth0
-    post-up dhclient $IFACE
+
     pre-down route add default dev eth0
 <% end %>
 #VAGRANT-END

test/unit/plugins/guests/alpine/cap/configure_networks_test.rb

@@ -4,39 +4,69 @@
 require_relative "../../../../base"
 
 describe 'VagrantPlugins::GuestAlpine::Cap::ConfigureNetworks' do
-    let(:described_class) do
-        VagrantPlugins::GuestAlpine::Plugin.components.guest_capabilities[:alpine].get(:configure_networks)
-    end
-    let(:machine) { double('machine') }
-    let(:communicator) { VagrantTests::DummyCommunicator::Communicator.new(machine) }
+  let(:described_class) do
+    VagrantPlugins::GuestAlpine::Plugin.components.guest_capabilities[:alpine].get(:configure_networks)
+  end
+  let(:machine) { double('machine') }
+  let(:communicator) { VagrantTests::DummyCommunicator::Communicator.new(machine) }
+
+  before do
+    allow(machine).to receive(:communicate).and_return(communicator)
+  end
+
+  after do
+    communicator.verify_expectations!
+  end
+
+  it 'should configure networks' do
+    networks = [
+      { type: :static, ip: '192.168.10.10', netmask: '255.255.255.0', interface: 0, name: 'eth0' },
+      { type: :dhcp, interface: 1, name: 'eth1' }
+    ]
+
+    expect(communicator).to receive(:sudo).with("sed -e '/^#VAGRANT-BEGIN/,$ d' /etc/network/interfaces > /tmp/vagrant-network-interfaces.pre")
+    expect(communicator).to receive(:sudo).with("sed -ne '/^#VAGRANT-END/,$ p' /etc/network/interfaces | tail -n +2 > /tmp/vagrant-network-interfaces.post")
+    expect(communicator).to receive(:sudo).with(/\/sbin\/ifdown eth0/)
+    expect(communicator).to receive(:sudo).with('/sbin/ip addr flush dev eth0 2> /dev/null')
+    expect(communicator).to receive(:sudo).with(/\/sbin\/ifdown eth1/)
+    expect(communicator).to receive(:sudo).with('/sbin/ip addr flush dev eth1 2> /dev/null')
+    expect(communicator).to receive(:sudo).with('cat /tmp/vagrant-network-interfaces.pre /tmp/vagrant-network-entry /tmp/vagrant-network-interfaces.post > /etc/network/interfaces')
+    expect(communicator).to receive(:sudo).with('rm -f /tmp/vagrant-network-interfaces.pre /tmp/vagrant-network-entry /tmp/vagrant-network-interfaces.post')
+    expect(communicator).to receive(:sudo).with('/sbin/ifup eth0')
+    expect(communicator).to receive(:sudo).with('/sbin/ifup eth1')
+
+    allow_message_expectations_on_nil
+
+    described_class.configure_networks(machine, networks)
+  end
+
+  context "dhcp assigned default route" do
+    let(:networks) {
+      [{type: :dhcp, use_dhcp_assigned_default_route: is_enabled}]
+    }
+    let(:is_enabled) { false }
+    let(:tempfile) { double(:tempfile, binmode: true, close: true, path: "/dev/null") }
 
     before do
-        allow(machine).to receive(:communicate).and_return(communicator)
+      allow(Tempfile).to receive(:new).and_return(tempfile)
     end
 
-    after do
-        communicator.verify_expectations!
-    end
-
-    it 'should configure networks' do
-        networks = [
-            { type: :static, ip: '192.168.10.10', netmask: '255.255.255.0', interface: 0, name: 'eth0' },
-            { type: :dhcp, interface: 1, name: 'eth1' }
-        ]
-
-        expect(communicator).to receive(:sudo).with("sed -e '/^#VAGRANT-BEGIN/,$ d' /etc/network/interfaces > /tmp/vagrant-network-interfaces.pre")
-        expect(communicator).to receive(:sudo).with("sed -ne '/^#VAGRANT-END/,$ p' /etc/network/interfaces | tail -n +2 > /tmp/vagrant-network-interfaces.post")
-        expect(communicator).to receive(:sudo).with(/\/sbin\/ifdown eth0/)
-        expect(communicator).to receive(:sudo).with('/sbin/ip addr flush dev eth0 2> /dev/null')
-        expect(communicator).to receive(:sudo).with(/\/sbin\/ifdown eth1/)
-        expect(communicator).to receive(:sudo).with('/sbin/ip addr flush dev eth1 2> /dev/null')
-        expect(communicator).to receive(:sudo).with('cat /tmp/vagrant-network-interfaces.pre /tmp/vagrant-network-entry /tmp/vagrant-network-interfaces.post > /etc/network/interfaces')
-        expect(communicator).to receive(:sudo).with('rm -f /tmp/vagrant-network-interfaces.pre /tmp/vagrant-network-entry /tmp/vagrant-network-interfaces.post')
-        expect(communicator).to receive(:sudo).with('/sbin/ifup eth0')
-        expect(communicator).to receive(:sudo).with('/sbin/ifup eth1')
-
-        allow_message_expectations_on_nil
+    context "when not enabled" do
+      it "should not configure default route" do
+        expect(tempfile).not_to receive(:write).with(/post-up route del default dev eth0/)
 
         described_class.configure_networks(machine, networks)
+      end
     end
+
+    context "when enabled" do
+      let(:is_enabled) { true }
+
+      it "should configure default route" do
+        expect(tempfile).to receive(:write).with(/post-up route del default dev eth0/)
+
+        described_class.configure_networks(machine, networks)
+      end
+    end
+  end
 end