Refactor tests specs with shared examples

spec/producer/core/tests/file_contains_spec.rb

@@ -8,9 +8,7 @@ module Producer::Core
       let(:content)   { 'some_content' }
       subject(:test)  { FileContains.new(env, filepath, content) }
 
-      it 'is a kind of test' do
-        expect(test).to be_a Test
-      end
+      it_behaves_like 'test'
 
       describe '#verify' do
         let(:fs) { double 'fs' }

spec/producer/core/tests/has_dir_spec.rb

@@ -7,9 +7,7 @@ module Producer::Core
       let(:path)        { 'some_directory' }
       subject(:has_dir) { HasDir.new(env, path) }
 
-      it 'is a kind of test' do
-        expect(has_dir).to be_a Test
-      end
+      it_behaves_like 'test'
 
       describe '#verify', :ssh do
         before { sftp_story }

spec/producer/core/tests/has_env_spec.rb

@@ -7,9 +7,7 @@ module Producer::Core
       let(:variable_name) { :some_variable_name }
       subject(:has_env)   { HasEnv.new(env, variable_name) }
 
-      it 'is a kind of test' do
-        expect(has_env).to be_a Test
-      end
+      it_behaves_like 'test'
 
       describe '#verify' do
         let(:environment) { double 'environment' }

spec/producer/core/tests/has_file_spec.rb

@@ -7,9 +7,7 @@ module Producer::Core
       let(:filepath)      { 'some_file' }
       subject(:has_file)  { HasFile.new(env, filepath) }
 
-      it 'is a kind of test' do
-        expect(has_file).to be_a Test
-      end
+      it_behaves_like 'test'
 
       describe '#verify', :ssh do
         before { sftp_story }