Print a message if the requirements files haven't changed.

rakefiles/helpers.rb

@@ -14,7 +14,7 @@ def report_dir_path(dir)
     return File.join(REPORT_DIR, dir.to_s)
 end
 
-def when_changed(*files)
+def when_changed(unchanged_message, *files)
     Rake::Task[PREREQS_MD5_DIR].invoke
     cache_file = File.join(PREREQS_MD5_DIR, files.join('-').gsub(/\W+/, '-')) + '.md5'
     digest = Digest::MD5.new()
@@ -24,6 +24,8 @@ def when_changed(*files)
     if !File.exists?(cache_file) or digest.hexdigest != File.read(cache_file)
         yield
         File.write(cache_file, digest.hexdigest)
+    elsif !unchanged_message.empty?
+        puts unchanged_message
     end
 end
 

rakefiles/prereqs.rake

@@ -12,21 +12,22 @@ task :install_prereqs => [:install_node_prereqs, :install_ruby_prereqs, :install
 
 desc "Install all node prerequisites for the lms and cms"
 task :install_node_prereqs => "ws:migrate" do
-    when_changed('package.json') do
+    when_changed('', 'package.json') do
         sh('npm install')
     end unless ENV['NO_PREREQ_INSTALL']
 end
 
 desc "Install all ruby prerequisites for the lms and cms"
 task :install_ruby_prereqs => "ws:migrate" do
-    when_changed('Gemfile') do
+    when_changed('', 'Gemfile') do
         sh('bundle install')
     end unless ENV['NO_PREREQ_INSTALL']
 end
 
 desc "Install all python prerequisites for the lms and cms"
 task :install_python_prereqs => "ws:migrate" do
-    when_changed('requirements/**/*') do
+    unchanged = 'Requirements files unchanged, nothing to install'
+    when_changed(unchanged, 'requirements/**/*') do
         ENV['PIP_DOWNLOAD_CACHE'] ||= '.pip_download_cache'
         sh('pip install --exists-action w -r requirements/edx/base.txt')
         sh('pip install --exists-action w -r requirements/edx/post.txt')