Implement `yaml_write' action

spec/producer/core/actions/yaml_writer_spec.rb

@@ -0,0 +1,25 @@
+require 'spec_helper'
+
+module Producer::Core
+  module Actions
+    describe YAMLWriter, :env do
+      let(:path)        { 'some_path' }
+      let(:data)        { { foo: 'bar' } }
+      let(:arguments)   { [path] }
+      let(:options)     { { data: data } }
+      subject(:writer)  { described_class.new(env, *arguments, options) }
+
+      it_behaves_like 'action'
+
+      it { is_expected.to be_a FileWriter}
+
+      describe '#apply' do
+        it 'writes data as YAML to file on remote filesystem' do
+          expect(remote_fs)
+            .to receive(:file_write).with(path, data.to_yaml)
+          writer.apply
+        end
+      end
+    end
+  end
+end