Rewrite seeded_rand() as a Puppet 4.x function

The 3.x function rely on is_integer() which is deprecated. Rewrite it
using the more modern puppet 4.x function to rely on data types for
better parameters validation.

Author: smortex

lib/puppet/functions/seeded_rand.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+# @summary
+#   Generates a random whole number greater than or equal to 0 and less than max, using the value of seed for repeatable randomness.
+Puppet::Functions.create_function(:seeded_rand) do
+  # @param max The maximum value.
+  # @param seed The seed used for repeatable randomness.
+  #
+  # @return [Integer]
+  #   A random number greater than or equal to 0 and less than max
+  dispatch :seeded_rand do
+    param 'Integer[1]', :max
+    param 'String', :seed
+  end
+
+  def seeded_rand(max, seed)
+    require 'digest/md5'
+
+    seed = Digest::MD5.hexdigest(seed).hex
+    Puppet::Util.deterministic_rand_int(seed, max)
+  end
+end

lib/puppet/parser/functions/seeded_rand.rb

@@ -4,18 +4,17 @@
 
 describe 'seeded_rand' do
   it { is_expected.not_to eq(nil) }
-  it { is_expected.to run.with_params.and_raise_error(ArgumentError, %r{wrong number of arguments}i) }
-  it { is_expected.to run.with_params(1).and_raise_error(ArgumentError, %r{wrong number of arguments}i) }
-  it { is_expected.to run.with_params(0, '').and_raise_error(ArgumentError, %r{first argument must be a positive integer}) }
-  it { is_expected.to run.with_params(1.5, '').and_raise_error(ArgumentError, %r{first argument must be a positive integer}) }
-  it { is_expected.to run.with_params(-10, '').and_raise_error(ArgumentError, %r{first argument must be a positive integer}) }
-  it { is_expected.to run.with_params('-10', '').and_raise_error(ArgumentError, %r{first argument must be a positive integer}) }
-  it { is_expected.to run.with_params('string', '').and_raise_error(ArgumentError, %r{first argument must be a positive integer}) }
-  it { is_expected.to run.with_params([], '').and_raise_error(ArgumentError, %r{first argument must be a positive integer}) }
-  it { is_expected.to run.with_params({}, '').and_raise_error(ArgumentError, %r{first argument must be a positive integer}) }
-  it { is_expected.to run.with_params(1, 1).and_raise_error(ArgumentError, %r{second argument must be a string}) }
-  it { is_expected.to run.with_params(1, []).and_raise_error(ArgumentError, %r{second argument must be a string}) }
-  it { is_expected.to run.with_params(1, {}).and_raise_error(ArgumentError, %r{second argument must be a string}) }
+  it { is_expected.to run.with_params.and_raise_error(ArgumentError, %r{'seeded_rand' expects 2 arguments, got none}i) }
+  it { is_expected.to run.with_params(1).and_raise_error(ArgumentError, %r{'seeded_rand' expects 2 arguments, got 1}i) }
+  it { is_expected.to run.with_params(0, '').and_raise_error(ArgumentError, %r{parameter 'max' expects an Integer\[1\] value, got Integer\[0, 0\]}) }
+  it { is_expected.to run.with_params(1.5, '').and_raise_error(ArgumentError, %r{parameter 'max' expects an Integer value, got Float}) }
+  it { is_expected.to run.with_params(-10, '').and_raise_error(ArgumentError, %r{parameter 'max' expects an Integer\[1\] value, got Integer\[-10, -10\]}) }
+  it { is_expected.to run.with_params('string', '').and_raise_error(ArgumentError, %r{parameter 'max' expects an Integer value, got String}) }
+  it { is_expected.to run.with_params([], '').and_raise_error(ArgumentError, %r{parameter 'max' expects an Integer value, got Array}) }
+  it { is_expected.to run.with_params({}, '').and_raise_error(ArgumentError, %r{parameter 'max' expects an Integer value, got Hash}) }
+  it { is_expected.to run.with_params(1, 1).and_raise_error(ArgumentError, %r{parameter 'seed' expects a String value, got Integer}) }
+  it { is_expected.to run.with_params(1, []).and_raise_error(ArgumentError, %r{parameter 'seed' expects a String value, got Array}) }
+  it { is_expected.to run.with_params(1, {}).and_raise_error(ArgumentError, %r{parameter 'seed' expects a String value, got Hash}) }
 
   context 'produce predictible and reproducible results' do
     it { is_expected.to run.with_params(20, 'foo').and_return(1) }