Merge pull request #949 from cocker-cc/feature/master/add_function_extname

add Function extname()

Author: david22swan

README.md

@@ -1368,6 +1368,21 @@ userlist:
 ensure_resources('user', hiera_hash('userlist'), {'ensure' => 'present'})
 ```
 
+#### `stdlib::extname`
+
+Returns the Extension (the Portion of Filename in Path starting from the last Period).
+
+Example usage:
+
+```puppet
+stdlib::extname('test.rb')       => '.rb'
+stdlib::extname('a/b/d/test.rb') => '.rb'
+stdlib::extname('test')          => ''
+stdlib::extname('.profile')      => ''
+```
+
+*Type*: rvalue.
+
 #### `fact`
 
 Return the value of a given fact. Supports the use of dot-notation for referring to structured facts. If a fact requested does not exist, returns Undef.

lib/puppet/functions/stdlib/extname.rb

@@ -0,0 +1,26 @@
+# Returns the Extension (the Portion of Filename in Path starting from the
+# last Period).
+#
+# If Path is a Dotfile, or starts with a Period, then the starting Dot is not
+# dealt with the Start of the Extension.
+#
+# An empty String will also be returned, when the Period is the last Character
+# in Path.
+
+Puppet::Functions.create_function(:'stdlib::extname') do
+  # @param filename The Filename
+  # @return [String] The Extension starting from the last Period
+  # @example Determining the Extension of a Filename
+  #   stdlib::extname('test.rb')       => '.rb'
+  #   stdlib::extname('a/b/d/test.rb') => '.rb'
+  #   stdlib::extname('test')          => ''
+  #   stdlib::extname('.profile')      => ''
+  dispatch :extname do
+    param 'String', :filename
+    return_type 'String'
+  end
+
+  def extname(filename)
+    File.extname(filename)
+  end
+end

spec/functions/extname_spec.rb

@@ -0,0 +1,16 @@
+require 'spec_helper'
+
+describe 'stdlib::extname' do
+  it { is_expected.not_to eq(nil) }
+  it { is_expected.to run.with_params.and_raise_error(ArgumentError, %r{'stdlib::extname' expects 1 argument, got none}) }
+  it { is_expected.to run.with_params('one', 'two').and_raise_error(ArgumentError, %r{'stdlib::extname' expects 1 argument, got 2}) }
+  it { is_expected.to run.with_params([]).and_raise_error(ArgumentError, %r{'stdlib::extname' parameter 'filename' expects a String value, got Array}) }
+  it { is_expected.to run.with_params('test.rb').and_return('.rb') }
+  it { is_expected.to run.with_params('a/b/d/test.rb').and_return('.rb') }
+  it { is_expected.to run.with_params('test').and_return('') }
+  it { is_expected.to run.with_params('.profile').and_return('') }
+
+  context 'with UTF8 and double byte characters' do
+    it { is_expected.to run.with_params('file_√ạĺűē/竹.rb').and_return('.rb') }
+  end
+end