Add Rakefile to replace crew test and simplify unit testing. (#10453)

Rakefile

@@ -0,0 +1,24 @@
+# The default action tests commands and libraries.
+task default: %w[command_test lib_test]
+
+# Command tests
+task :command_test do
+  ruby 'tests/commands/const.rb'
+  ruby 'tests/commands/help.rb'
+  ruby 'tests/commands/list.rb'
+  ruby 'tests/commands/prop.rb'
+  ruby 'tests/commands/remove.rb'
+  ruby 'tests/commands/whatprovides.rb'
+end
+
+# Library tests
+task :lib_test do
+  ruby 'tests/lib/docopt.rb'
+  ruby 'tests/lib/package_utils.rb'
+end
+
+# Package tests
+task :package_test do
+  ruby 'tests/prop_test'
+  ruby 'tests/buildsystem_test'
+end