test: add tests for provider command

plugins/commands/provider/command.rb

@@ -46,7 +46,7 @@ module VagrantPlugins
 
         # Check if we're just doing a usability check
         if options[:usable]
-          puts machine.provider_name.to_s
+          @env.ui.output(machine.provider_name.to_s)
           return 0 if machine.provider.class.usable?(false)
           return 1
         end
@@ -59,8 +59,12 @@ module VagrantPlugins
           end
 
           machine.provider.capability(:install)
+          return
         end
 
+        # No subtask, just output the provider name
+        @env.ui.output(machine.provider_name.to_s)
+
         # Success, exit status 0
         0
       end

test/unit/plugins/commands/provider/command_test.rb

@@ -0,0 +1,47 @@
+require File.expand_path("../../../../base", __FILE__)
+
+require Vagrant.source_root.join("plugins/commands/provider/command")
+
+describe VagrantPlugins::CommandProvider::Command do
+  include_context "unit"
+
+  let(:iso_env) do
+    # We have to create a Vagrantfile so there is a root path
+    env = isolated_environment
+    env.vagrantfile("")
+    env.create_vagrant_env
+  end
+
+  let(:guest)   { double("guest") }
+  let(:host)    { double("host") }
+  let(:machine) { iso_env.machine(iso_env.machine_names[0], :dummy) }
+
+  let(:argv)     { [] }
+
+  subject { described_class.new(argv, iso_env) }
+
+  before do
+    allow(subject).to receive(:with_target_vms) { |&block| block.call machine }
+  end
+
+  describe "execute" do
+    context "no arguments" do
+      it "exits with the provider name" do
+        expect(subject.execute).to eq(0)
+      end
+    end
+
+    context "--usable" do
+      let(:argv) { ["--usable"] }
+
+      it "exits 0 if it is usable" do
+        expect(subject.execute).to eq(0)
+      end
+
+      it "exits 1 if it is not usable" do
+        expect(machine.provider.class).to receive(:usable?).and_return(false)
+        expect(subject.execute).to eq(1)
+      end
+    end
+  end
+end