Porting functions to the modern Puppet 4.x API

lib/puppet/functions/merge_hiera_hashes.rb

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+# This is an autogenerated function, ported from the original legacy version.
+# It /should work/ as is, but will not have all the benefits of the modern
+# function API. You should see the function docs to learn how to add function
+# signatures for type safety and to document this function using puppet-strings.
+#
+# https://puppet.com/docs/puppet/latest/custom_functions_ruby.html
+#
+# ---- original file header ----
+require 'hiera'
+
+# ---- original file header ----
+#
+# @summary
+#       Merges the hiera hashes supplied as arguments. Takes an array of Strings
+#    containing Hiera names and an optional name space to qualify this array's
+#    entries with.
+#
+#    Example:
+#
+#    Given the following Hiera hash,
+#
+#        my::hash1:
+#          one: 1
+#          two: 2
+#        my::hash2:
+#          one: 'one'
+#          three: 3
+#
+#    this assignment:
+#
+#      $res = merge_hiera_hashes(['my::hash1', 'my::hash2'])
+#
+#    would place the following result hash in $res:
+#
+#      $res =  {'one' => 'one', 'two' => 2, 'three' => 3}
+#
+#    If a key occurs multiple times, the value in the rightmost Hiera hash will
+#    end up in the final hash under that key.
+#
+#    Alternatively, the same result can be obtained by specifying a Hiera name
+#    space as follows:
+#
+#      $res = merge_hiera_hashes(['hash1', 'hash2'], 'my')
+#
+#
+#
+Puppet::Functions.create_function(:'merge_hiera_hashes') do
+  # @param args
+  #   The original array of arguments. Port this to individually managed params
+  #   to get the full benefit of the modern function API.
+  #
+  # @return [Data type]
+  #   Describe what the function returns here
+  #
+  dispatch :default_impl do
+    # Call the method named 'default_impl' when this is matched
+    # Port this to match individual params for better type safety
+    repeated_param 'Any', :args
+  end
+
+
+  def default_impl(*args)
+
+
+    if args.length < 1
+      raise Puppet::ParseError, ("merge_hiera_hashes(): wrong number of arguments (#{args.length}; needs at least one argument)")
+    end
+
+    names = args.shift()   # Names to look up
+
+    namespace = nil        # Optional Name space to qualify lookups with
+
+    unless ( args.empty? )
+      if ( (args.first.class == String) and args.first != '' )
+        namespace = args.shift()
+      end
+    end
+
+    res = Hash.new         # Will hold results
+
+    names.each do |name|
+      unless name.is_a?String
+        warning("merge_hiera_hashes: This does not look like a hiera name #{name.class.to_s} (expected String), skipping.")
+        next
+      end
+
+      unless ( namespace.nil? )
+        name = [namespace, name].join('::')
+      end
+
+      begin
+        hiera_res = function_hiera_hash([name])
+      rescue => e
+        warning("merge_hiera_hashes: Hiera lookup of #{name} (namespace: #{namespace}) failed: '#{e.to_s}', skipping.")
+        next
+      end
+
+      unless hiera_res.is_a?(Hash)
+        warning("merge_hiera_hash: Unexpected type #{hiera_res.class} for #{name} (expeced Hash), skipping.")
+        next
+      end
+
+      res.merge!(hiera_res)
+    end
+
+    res
+
+  end
+end

spec/functions/_merge_hiera_hashes_spec.rb

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+require 'spec_helper'
+
+describe 'merge_hiera_hashes' do
+  # without knowing details about the implementation, this is the only test
+  # case that we can autogenerate. You should add more examples below!
+  it { is_expected.not_to eq(nil) }
+
+#################################
+# Below are some example test cases. You may uncomment and modify them to match
+# your needs. Notice that they all expect the base error class of `StandardError`.
+# This is because the autogenerated function uses an untyped array for parameters
+# and relies on your implementation to do the validation. As you convert your
+# function to proper dispatches and typed signatures, you should change the
+# expected error of the argument validation examples to `ArgumentError`.
+#
+# Other error types you might encounter include
+#
+# * StandardError
+# * ArgumentError
+# * Puppet::ParseError
+#
+# Read more about writing function unit tests at https://rspec-puppet.com/documentation/functions/
+#
+#   it 'raises an error if called with no argument' do
+#     is_expected.to run.with_params.and_raise_error(StandardError)
+#   end
+#
+#   it 'raises an error if there is more than 1 arguments' do
+#     is_expected.to run.with_params({ 'foo' => 1 }, 'bar' => 2).and_raise_error(StandardError)
+#   end
+#
+#   it 'raises an error if argument is not the proper type' do
+#     is_expected.to run.with_params('foo').and_raise_error(StandardError)
+#   end
+#
+#   it 'returns the proper output' do
+#     is_expected.to run.with_params(123).and_return('the expected output')
+#   end
+#################################
+
+end