added test example for plugin and lib

test/lib/composure.bats

@@ -3,7 +3,7 @@
 load ../test_helper
 load ../../lib/composure
 
-@test "composure_keywords()" {
+@test "lib composure: composure_keywords()" {
   run composure_keywords
   assert_output "about author example group param version"
 }

test/plugins/ruby.plugin.bats

@@ -0,0 +1,16 @@
+#!/usr/bin/env bats
+
+load ../test_helper
+load ../../lib/composure
+load ../../plugins/available/ruby.plugin
+
+@test "plugins ruby: remove_gem is defined" {
+  run type remove_gem
+  assert_line 1 "remove_gem () "
+}
+
+
+@test "plugins ruby: PATH includes ~/.gem/ruby/bin" {
+  last_path_entry=$(echo $PATH | tr ":" "\n" | tail -1);
+  [[ "${last_path_entry}" == "${HOME}"/.gem/ruby/*/bin ]]
+}