(maint) add puppetdb_query test

Author: h0tw1r3

spec/support/acceptance/shared/puppetdb.rb

@@ -45,4 +45,8 @@ class { 'puppetdb':
   it 'applies idempotently' do
     idempotent_apply(pp, debug: ENV.key?('DEBUG'))
   end
+
+  it 'agent can puppetdb_query' do
+    apply_manifest("$envs = puppetdb_query('environments[name]{}')", expect_failures: false, debug: ENV.key?('DEBUG'))
+  end
 end