Add a round function to complement ceiling and floor

Author: npwalker

README.markdown

@@ -996,6 +996,10 @@ Searches through an array and rejects all elements that match the provided regul
 
 Reverses the order of a string or array. *Type*: rvalue.
 
+#### `stdlib::round`
+
+Rounds a number to the nearest integer 
+
 #### `rstrip`
 
 Strips spaces to the right of the string. *Type*: rvalue.
@@ -1501,7 +1505,7 @@ The deprecation messages you get can vary, depending on the modules and data tha
 
 The `validate_legacy` function helps you move from Puppet 3 style validation to Puppet 4 validation without breaking functionality your module's users depend on.
 
-Moving to Puppet 4 type validation allows much better defined type checking using [data types](https://docs.puppet.com/puppet/latest/reference/lang_data.html). Many of Puppet 3's `validate_*` functions have surprising holes in their validation. For example, [validate_numeric](#validate_numeric) allows not only numbers, but also arrays of numbers or strings that look like numbers, without giving you any control over the specifics. 
+Moving to Puppet 4 type validation allows much better defined type checking using [data types](https://docs.puppet.com/puppet/latest/reference/lang_data.html). Many of Puppet 3's `validate_*` functions have surprising holes in their validation. For example, [validate_numeric](#validate_numeric) allows not only numbers, but also arrays of numbers or strings that look like numbers, without giving you any control over the specifics.
 
 For each parameter of your classes and defined types, choose a new Puppet 4 data type to use. In most cases, the new data type allows a different set of values than the original `validate_*` function. The situation then looks like this:
 

functions/round.pp

@@ -0,0 +1,9 @@
+function stdlib::round(
+  Numeric $input,
+) {
+  if $input >= 0 {
+    Integer( $input + 0.5 )
+  } else {
+    Integer( $input - 0.5 )
+  }
+}

spec/functions/round_spec.rb

@@ -0,0 +1,17 @@
+require 'spec_helper'
+
+describe 'stdlib::round' do
+  it { is_expected.not_to eq(nil) }
+  it { is_expected.to run.with_params()
+    .and_raise_error(ArgumentError('stdlib::round' expects 1 argument, got none)) }
+  it { is_expected.to run.with_params("foo")
+    .and_raise_error(ArgumentError('stdlib::round' parameter 'input' expects a Numeric value, got String)) }
+  it { is_expected.to run.with_params([])
+    .and_raise_error(ArgumentError('stdlib::round' parameter 'input' expects a Numeric value, got Array)) }
+  it { is_expected.to run.with_params(34.3).and_return(34) }
+  it { is_expected.to run.with_params(-34.3).and_return(-34) }
+  it { is_expected.to run.with_params(34.5).and_return(35) }
+  it { is_expected.to run.with_params(-34.5).and_return(-35) }
+  it { is_expected.to run.with_params(34.7).and_return(35) }
+  it { is_expected.to run.with_params(-34.7).and_return(-35) }
+end