Implement `file_eq' condition keyword

spec/producer/core/condition/dsl_spec.rb

@@ -11,6 +11,7 @@ module Producer::Core
         `
         sh
         file_contains
+        file_eq
         dir?
         env?
         executable?

spec/producer/core/tests/file_eq_spec.rb

@@ -0,0 +1,45 @@
+require 'spec_helper'
+
+module Producer::Core
+  module Tests
+    describe FileEq, :env do
+      let(:filepath)  { 'some_file' }
+      let(:content)   { 'some content' }
+      subject(:test)  { FileEq.new(env, filepath, content) }
+
+      it_behaves_like 'test'
+
+      describe '#verify' do
+        context 'when file content matches' do
+          before do
+            allow(remote_fs).to receive(:file_read).with(filepath) { content }
+          end
+
+          it 'returns true' do
+            expect(test.verify).to be true
+          end
+        end
+
+        context 'when file content does not match' do
+          before do
+            allow(remote_fs).to receive(:file_read).with(filepath) { 'foo bar' }
+          end
+
+          it 'returns false' do
+            expect(test.verify).to be false
+          end
+        end
+
+        context 'when file does not exist' do
+          before do
+            allow(remote_fs).to receive(:file_read).with(filepath) { nil }
+          end
+
+          it 'returns false' do
+            expect(test.verify).to be false
+          end
+        end
+      end
+    end
+  end
+end