Implement `has_file' condition keyword

features/steps/remote_steps.rb

@@ -0,0 +1,3 @@
+Given(/^a remote file named "(.*?)"$/) do |file_name|
+  write_file file_name, ''
+end

features/tests/has_file.feature

@@ -0,0 +1,23 @@
+@sshd
+Feature: `has_file' condition keyword
+
+  Background:
+    Given a recipe with:
+      """
+      target 'some_host.test'
+
+      task :testing_file_existence do
+        condition { has_file 'some_file' }
+
+        echo 'evaluated'
+      end
+      """
+
+  Scenario: succeeds when file exists
+    Given a remote file named "some_file"
+    When I successfully execute the recipe
+    Then the output must contain "evaluated"
+
+  Scenario: fails when file does not exist
+    When I successfully execute the recipe
+    Then the output must not contain "evaluated"

lib/producer/core.rb

@@ -6,6 +6,7 @@ require 'producer/core/actions/shell_command'
 # condition tests (need to be defined before the condition DSL)
 require 'producer/core/test'
 require 'producer/core/tests/has_env'
+require 'producer/core/tests/has_file'
 
 require 'producer/core/cli'
 require 'producer/core/condition'

lib/producer/core/condition/dsl.rb

@@ -16,7 +16,8 @@ module Producer
           end
         end
 
-        define_test :has_env, Tests::HasEnv
+        define_test :has_env,   Tests::HasEnv
+        define_test :has_file,  Tests::HasFile
 
         attr_accessor :tests
 

lib/producer/core/tests/has_file.rb

@@ -0,0 +1,11 @@
+module Producer
+  module Core
+    module Tests
+      class HasFile < Test
+        def success?
+          env.remote.fs.has_file? arguments.first
+        end
+      end
+    end
+  end
+end

spec/producer/core/condition/dsl_spec.rb

@@ -6,7 +6,7 @@ module Producer::Core
     let(:env)     { double('env') }
     subject(:dsl) { Condition::DSL.new(env, &block) }
 
-    %w[has_env].each do |test|
+    %w[has_env has_file].each do |test|
       it "has `#{test}' test defined" do
         expect(dsl).to respond_to test.to_sym
       end

spec/producer/core/tests/has_file_spec.rb

@@ -0,0 +1,28 @@
+require 'spec_helper'
+
+module Producer::Core
+  describe Tests::HasFile do
+    let(:env)           { Env.new }
+    let(:filepath)      { 'some_file' }
+    subject(:has_file)  { Tests::HasFile.new(env, filepath) }
+
+    it 'is a kind of test' do
+      expect(has_file).to be_a Test
+    end
+
+    describe '#success?', :ssh do
+      before { sftp_story }
+
+      it 'delegates the call on remote FS' do
+        expect(env.remote.fs).to receive(:has_file?).with(filepath)
+        has_file.success?
+      end
+
+      it 'returns the file existence' do
+        existence = double('existence')
+        allow(env.remote.fs).to receive(:has_file?) { existence }
+        expect(has_file.success?).to be existence
+      end
+    end
+  end
+end