diff --git a/lib/puppet/functions/archive/assemble_nexus_url.rb b/lib/puppet/functions/archive/assemble_nexus_url.rb
new file mode 100644
index 0000000..0ad8d63
--- /dev/null
+++ b/lib/puppet/functions/archive/assemble_nexus_url.rb
@@ -0,0 +1,27 @@
+require 'cgi'
+
+# @summary
+#   Assembles a complete nexus URL from the base url and query parameters
+# @api private
+Puppet::Functions.create_function(:'archive::assemble_nexus_url') do
+  # @param nexus_url
+  #   The base nexus URL
+  # @param params
+  #   The query parameters as a hash
+  #
+  # @return [Stdlib::HTTPUrl]
+  #   The assembled URL
+  dispatch :default_impl do
+    param 'Stdlib::HTTPUrl', :nexus_url
+    param 'Hash', :params
+    return_type 'Stdlib::HTTPUrl'
+  end
+
+  def default_impl(nexus_url, params)
+    service_relative_url = 'service/local/artifact/maven/content'
+
+    query_string = params.to_a.map { |x| "#{x[0]}=#{CGI.escape(x[1])}" }.join('&')
+
+    "#{nexus_url}/#{service_relative_url}?#{query_string}"
+  end
+end
diff --git a/lib/puppet/parser/functions/assemble_nexus_url.rb b/lib/puppet/parser/functions/assemble_nexus_url.rb
deleted file mode 100644
index be7c6e0..0000000
--- a/lib/puppet/parser/functions/assemble_nexus_url.rb
+++ /dev/null
@@ -1,13 +0,0 @@
-require 'cgi'
-
-module Puppet::Parser::Functions
-  newfunction(:assemble_nexus_url, type: :rvalue) do |args|
-    service_relative_url = 'service/local/artifact/maven/content'
-
-    nexus_url = args[0]
-    params = args[1]
-    query_string = params.to_a.map { |x| "#{x[0]}=#{CGI.escape(x[1])}" }.join('&')
-
-    "#{nexus_url}/#{service_relative_url}?#{query_string}"
-  end
-end
diff --git a/manifests/nexus.pp b/manifests/nexus.pp
index 16eb854..17e27df 100644
--- a/manifests/nexus.pp
+++ b/manifests/nexus.pp
@@ -1,114 +1,114 @@
 # define: archive::nexus
 # ======================
 #
 # archive wrapper for downloading files from Nexus using REST API. Nexus API:
 # https://repository.sonatype.org/nexus-restlet1x-plugin/default/docs/path__artifact_maven_content.html
 #
 # Parameters
 # ----------
 #
 # Examples
 # --------
 #
 # archive::nexus { '/tmp/jtstand-ui-0.98.jar':
 #   url        => 'https://oss.sonatype.org',
 #   gav        => 'org.codehaus.jtstand:jtstand-ui:0.98',
 #   repository => 'codehaus-releases',
 #   packaging  => 'jar',
 #   extract    => false,
 # }
 #
 define archive::nexus (
   String            $url,
   String            $gav,
   String            $repository,
   Enum['present', 'absent'] $ensure  = present,
   Enum['none', 'md5', 'sha1', 'sha2','sha256', 'sha384', 'sha512'] $checksum_type   = 'md5',
   Boolean           $checksum_verify = true,
   String            $packaging       = 'jar',
   Boolean           $use_nexus3_urls = false,
   Optional[String]  $classifier      = undef,
   Optional[String]  $extension       = undef,
   Optional[String]  $username        = undef,
   Optional[String]  $password        = undef,
   Optional[String]  $user            = undef,
   Optional[String]  $owner           = undef,
   Optional[String]  $group           = undef,
   Optional[String]  $mode            = undef,
   Optional[Boolean] $extract         = undef,
   Optional[String]  $extract_path    = undef,
   Optional[String]  $extract_flags   = undef,
   Optional[String]  $extract_command = undef,
   Optional[String]  $creates         = undef,
   Optional[Boolean] $cleanup         = undef,
   Optional[String]  $proxy_server    = undef,
   Optional[String]  $proxy_type      = undef,
   Optional[Boolean] $allow_insecure  = undef,
 ) {
 
   include archive::params
 
   $artifact_info = split($gav, ':')
 
   $group_id = $artifact_info[0]
   $artifact_id = $artifact_info[1]
   $version = $artifact_info[2]
 
   $query_params = {
 
     'g' => $group_id,
     'a' => $artifact_id,
     'v' => $version,
     'r' => $repository,
     'p' => $packaging,
     'c' => $classifier,
     'e' => $extension,
 
   }.filter |$keys, $values| { $values != undef }
 
   if $use_nexus3_urls {
     if $classifier {
       $c = "-${classifier}"
     } else {
       $c = ''
     }
     $artifact_url = sprintf('%s/repository/%s/%s/%s/%s/%s-%s%s.%s', $url,
                             $repository, regsubst($group_id, '\.', '/', 'G'), $artifact_id,
                             $version, $artifact_id, $version, $c, $packaging)
     $checksum_url = sprintf('%s.%s', $artifact_url, $checksum_type)
   } else {
-    $artifact_url = assemble_nexus_url($url, $query_params)
+    $artifact_url = archive::assemble_nexus_url($url, $query_params)
     $checksum_url = regsubst($artifact_url, "p=${packaging}", "p=${packaging}.${checksum_type}")
   }
   archive { $name:
     ensure          => $ensure,
     source          => $artifact_url,
     username        => $username,
     password        => $password,
     checksum_url    => $checksum_url,
     checksum_type   => $checksum_type,
     checksum_verify => $checksum_verify,
     extract         => $extract,
     extract_path    => $extract_path,
     extract_flags   => $extract_flags,
     extract_command => $extract_command,
     user            => $user,
     group           => $group,
     creates         => $creates,
     cleanup         => $cleanup,
     proxy_server    => $proxy_server,
     proxy_type      => $proxy_type,
     allow_insecure  => $allow_insecure,
   }
 
   $file_owner = pick($owner, $archive::params::owner)
   $file_group = pick($group, $archive::params::group)
   $file_mode  = pick($mode, $archive::params::mode)
 
   file { $name:
     owner   => $file_owner,
     group   => $file_group,
     mode    => $file_mode,
     require => Archive[$name],
   }
 }
diff --git a/spec/unit/puppet/parser/functions/assemble_nexus_url_spec.rb b/spec/functions/archive_assemble_nexus_url_spec.rb
similarity index 60%
rename from spec/unit/puppet/parser/functions/assemble_nexus_url_spec.rb
rename to spec/functions/archive_assemble_nexus_url_spec.rb
index 4be1984..ef6fef4 100644
--- a/spec/unit/puppet/parser/functions/assemble_nexus_url_spec.rb
+++ b/spec/functions/archive_assemble_nexus_url_spec.rb
@@ -1,39 +1,35 @@
 require 'spec_helper'
 
-describe :assemble_nexus_url do # rubocop:disable RSpec/DescribeSymbol
-  before :all do # rubocop:disable RSpec/BeforeAfterAll
-    Puppet::Parser::Functions.autoloader.loadall
-  end
-
-  let(:scope) { PuppetlabsSpec::PuppetInternals.scope }
+describe 'archive::assemble_nexus_url' do
+  let(:nexus_url) { 'http://nexus.local' }
 
-  nexus_url = 'http://nexus.local'
+  it { is_expected.not_to eq(nil) }
 
   it 'builds url correctly' do
     expected_url = 'http://nexus.local/service/local/artifact/maven/content?g=com.test&a=test&v=1.0.0&r=binary-staging&p=ear'
 
     parameters = {
       'g' => 'com.test',
       'a' => 'test',
       'v' => '1.0.0',
       'r' => 'binary-staging',
       'p' => 'ear'
     }
 
-    expect(scope.function_assemble_nexus_url([nexus_url, parameters])).to eq expected_url
+    is_expected.to run.with_params(nexus_url, parameters).and_return(expected_url)
   end
 
   it 'builds url with version containing "+" sign correctly' do
     expected_url = 'http://nexus.local/service/local/artifact/maven/content?g=com.test&a=test&v=1.0.0%2B11&r=binary-staging&p=ear'
 
     parameters = {
       'g' => 'com.test',
       'a' => 'test',
       'v' => '1.0.0+11',
       'r' => 'binary-staging',
       'p' => 'ear'
     }
 
-    expect(scope.function_assemble_nexus_url([nexus_url, parameters])).to eq expected_url
+    is_expected.to run.with_params(nexus_url, parameters).and_return(expected_url)
   end
 end