guests/linux: Add tests for choosing addressable IP

plugins/guests/linux/cap/choose_addressable_ip_addr.rb

@@ -3,12 +3,12 @@ module VagrantPlugins
     module Cap
       module ChooseAddressableIPAddr
         def self.choose_addressable_ip_addr(machine, possible)
-          machine.communicate.tap do |comm|
-            possible.each do |ip|
-              command = "ping -c1 -w1 -W1 #{ip}"
-              if comm.test(command)
-                return ip
-              end
+          comm = machine.communicate
+
+          possible.each do |ip|
+            command = "ping -c1 -w1 -W1 #{ip}"
+            if comm.test(command)
+              return ip
             end
           end
 

test/unit/plugins/guests/linux/cap/choose_addressable_ip_addr_test.rb

@@ -0,0 +1,38 @@
+require_relative "../../../../base"
+
+describe "VagrantPlugins::GuestLinux::Cap::ChooseAddressableIPAddr" do
+  let(:caps) do
+    VagrantPlugins::GuestLinux::Plugin
+      .components
+      .guest_capabilities[:linux]
+  end
+
+  let(:machine) { double("machine") }
+  let(:comm) { VagrantTests::DummyCommunicator::Communicator.new(machine) }
+
+  before do
+    allow(machine).to receive(:communicate).and_return(comm)
+  end
+
+  after do
+    comm.verify_expectations!
+  end
+
+  describe ".choose_addressable_ip_addr" do
+    let(:cap) { caps.get(:choose_addressable_ip_addr) }
+
+    it "returns the first matching IP address" do
+      possible = ["1.2.3.4", "5.6.7.8"]
+      possible.each do |ip|
+        comm.stub_command("ping -c1 -w1 -W1 #{ip}", exit_code: 0)
+      end
+      result = cap.choose_addressable_ip_addr(machine, possible)
+      expect(result).to eq("1.2.3.4")
+    end
+
+    it "returns nil when there are no matches" do
+      result = cap.choose_addressable_ip_addr(machine, [])
+      expect(result).to be(nil)
+    end
+  end
+end