Switch to rspec3 matchers

Running the specs with rspec3 leads to the following deprecation
warning:

    Using `should` from rspec-expectations' old `:should` syntax without
    explicitly enabling the syntax is deprecated. Use the new `:expect`
    syntax or explicitly enable `:should` instead

So switch to the new expect syntax

spec/unit/provider/rpmkey/rpm_spec.rb

@@ -10,33 +10,33 @@ describe Puppet::Type.type(:rpmkey).provider(:rpm) do
 
   describe ".instances" do
     it "should have an instances method" do
-      described_class.should respond_to :instances
+      expect(described_class).to respond_to(:instances)
     end
 
     it "should get installed rpm keys by running rpm -q" do
       described_class.expects(:rpm).with('-q', 'gpg-pubkey').returns File.read(my_fixture('rpm_q'))
-      described_class.instances.map(&:name).should == [
+      expect(described_class.instances.map(&:name)).to eq([
         'DB42A60E',
         '4F2A6FD2',
         '23A254D4'
-      ]
+      ])
     end
 
     it "should return an empty list if no key is installed" do
       described_class.expects(:rpm).with('-q', 'gpg-pubkey').raises Puppet::ExecutionFailure, 'package gpg-pubkey is not installed'
-      described_class.instances.should be_empty
+      expect(described_class.instances).to be_empty
     end
   end
 
   describe "#exists?" do
     it "should return true if the resource is present" do
       provider = described_class.new(:name => 'DB42A60E', :ensure => :present)
-      provider.should be_exists
+      expect(provider).to be_exists
     end
 
     it "should return false if the resource is absent" do
       provider = described_class.new(:name => 'DB42A60E', :ensure => :absent)
-      provider.should_not be_exists
+      expect(provider).not_to be_exists
     end
   end
 

spec/unit/type/rpmkey_spec.rb

@@ -5,19 +5,19 @@ require 'spec_helper'
 describe Puppet::Type.type(:rpmkey) do
 
   it "should have :name as its keyattribute" do
-    described_class.key_attributes.should == [:name]
+    expect(described_class.key_attributes).to eq([:name])
   end
 
   describe "when validating attributes" do
     [:name, :source, :provider].each do |param|
       it "should have a #{param} parameter" do
-        described_class.attrtype(param).should == :param
+        expect(described_class.attrtype(param)).to eq(:param)
       end
     end
 
     [:ensure].each do |property|
       it "should have a #{property} property" do
-        described_class.attrtype(property).should == :property
+        expect(described_class.attrtype(property)).to eq(:property)
       end
     end
   end