Add unit test of Swift::MountDevice type

Change-Id: I4486bf134e068b95c1ec71848efabd24069b186b
(cherry picked from commit 9ac945a2cb)

spec/type_aliases/mountdevice_spec.rb

@@ -0,0 +1,33 @@
+require 'spec_helper'
+
+describe 'Swift::MountDevice' do
+  describe 'valid types' do
+    context 'with valid types' do
+      [
+        '/dev',
+        '/dev/sda',
+        '/opt/swift/diskfile',
+        'LABEL=foo'
+      ].each do |value|
+        it { is_expected.to allow_value(value) }
+      end
+    end
+  end
+
+  describe 'invalid types' do
+    context 'with invalid types' do
+      [
+        1,
+        true,
+        {},
+        ['/dev/sda'],
+        'dev',
+        'dev/sda',
+        'LABEL=',
+        'LABELfoo'
+      ].each do |value|
+        it { is_expected.not_to allow_value(value) }
+      end
+    end
+  end
+end