Use instance doubles

This verifies in the stubbed methods match the function signatures.

spec/beaker_puppet_helpers/dsl_spec.rb

@@ -14,8 +14,8 @@ def logger
 describe BeakerPuppetHelpers::DSL do
   subject(:dsl) { ClassMixedWithDSLHelpers.new }
 
-  let(:master) { double('Beaker::Host') }
-  let(:agent)  { double('Beaker::Host') }
+  let(:master) { instance_double(Beaker::Host) }
+  let(:agent)  { instance_double(Beaker::Host) }
   let(:hosts)  { [master, agent] }
 
   describe '#apply_manifest_on' do
@@ -179,7 +179,7 @@ def logger
 
   describe '#fact_on' do
     it 'retrieves a fact on a single host' do
-      result = double('Beaker::Result', stdout: '{"osfamily": "family"}')
+      result = instance_double(Beaker::Result, stdout: '{"osfamily": "family"}')
       expect(dsl).to receive(:on).and_return(result)
 
       expect(dsl.fact_on('host', 'osfamily')).to eq('family')
@@ -188,21 +188,21 @@ def logger
     it 'converts each element to a structured fact when it receives an array of results from #on' do
       times = hosts.length
 
-      result = double('Beaker::Result', stdout: '{"os": {"name":"name", "family": "family"}}')
+      result = instance_double(Beaker::Result, stdout: '{"os": {"name":"name", "family": "family"}}')
       allow(dsl).to receive(:on).and_return([result] * times)
 
       expect(dsl.fact_on(hosts, 'os')).to eq([{ 'name' => 'name', 'family' => 'family' }] * times)
     end
 
     it 'returns a single result for single host' do
-      result = double('Beaker::Result', stdout: '{"osfamily": "family"}')
+      result = instance_double(Beaker::Result, stdout: '{"osfamily": "family"}')
       allow(dsl).to receive(:on).and_return(result)
 
       expect(dsl.fact_on('host', 'osfamily')).to eq('family')
     end
 
     it 'preserves data types' do
-      result = double('Beaker::Result', stdout: '{"identity": { "uid": 0, "user": "root", "privileged": true }}')
+      result = instance_double(Beaker::Result, stdout: '{"identity": { "uid": 0, "user": "root", "privileged": true }}')
       allow(dsl).to receive(:on).and_return(result)
 
       structured_fact = dsl.fact_on('host', 'identity')

spec/beaker_puppet_helpers/install_utils_spec.rb

@@ -4,7 +4,7 @@
 
 describe BeakerPuppetHelpers::InstallUtils do
   describe '.install_puppet_release_repo_on' do
-    let(:host) { double('Beaker::Host') }
+    let(:host) { instance_double(Beaker::Host) }
     let(:packaging_platform) { Beaker::Platform.new(platform) }
 
     before { allow(host).to receive(:[]).with('packaging_platform').and_return(packaging_platform) }

spec/beaker_puppet_helpers/module_utils_spec.rb

@@ -14,7 +14,7 @@ def logger
 describe BeakerPuppetHelpers::ModuleUtils do
   subject(:dsl) { ClassMixedWithDSLInstallUtils.new }
 
-  let(:host) { double('Beaker::Host') }
+  let(:host) { instance_double(Beaker::Host) }
 
   describe '#install_puppet_module_via_pmt_on' do
     let(:default_module_install_opts) { nil }
@@ -82,7 +82,7 @@ def logger
   end
 
   describe '#install_local_module_on' do
-    let(:builder) { double('Puppet::Modulebuilder::Builder') }
+    let(:builder) { instance_double(Puppet::Modulebuilder::Builder) }
 
     it 'builds and copies the module' do
       expect(File).to receive(:realpath).with('.').and_return('/path/to/module')