Convert tests to use plain rspec-puppet

Tests in the new style produces the following documentation output:

abs
  should not eq nil
  should run abs() and raise an Puppet::ParseError
  should run abs(-34) and return 34
  should run abs("-34") and return 34
  should run abs(34) and return 34
  should run abs("34") and return 34

1 files changed, 9 insertions, 31 deletions

diff --git a/spec/functions/pick_spec.rb b/spec/functions/pick_spec.rb
index 8be8f58..2c7caa8 100755
--- a/spec/functions/pick_spec.rb
+++ b/spec/functions/pick_spec.rb
@@ -1,34 +1,12 @@
-#!/usr/bin/env ruby -S rspec
 require 'spec_helper'
 
-describe "the pick function" do
-  let(:scope) { PuppetlabsSpec::PuppetInternals.scope }
-
-  it "should exist" do
-    expect(Puppet::Parser::Functions.function("pick")).to eq("function_pick")
-  end
-
-  it 'should return the correct value' do
-    expect(scope.function_pick(['first', 'second'])).to eq('first')
-  end
-
-  it 'should return the correct value if the first value is empty' do
-    expect(scope.function_pick(['', 'second'])).to eq('second')
-  end
-
-  it 'should remove empty string values' do
-    expect(scope.function_pick(['', 'first'])).to eq('first')
-  end
-
-  it 'should remove :undef values' do
-    expect(scope.function_pick([:undef, 'first'])).to eq('first')
-  end
-
-  it 'should remove :undefined values' do
-    expect(scope.function_pick([:undefined, 'first'])).to eq('first')
-  end
-
-  it 'should error if no values are passed' do
-    expect { scope.function_pick([]) }.to( raise_error(Puppet::ParseError, "pick(): must receive at least one non empty value"))
-  end
+describe 'pick' do
+  it { is_expected.not_to eq(nil) }
+  it { is_expected.to run.with_params().and_raise_error(Puppet::ParseError, /must receive at least one non empty value/) }
+  it { is_expected.to run.with_params('', nil, :undef, :undefined).and_raise_error(Puppet::ParseError, /must receive at least one non empty value/) }
+  it { is_expected.to run.with_params('one', 'two').and_return('one') }
+  it { is_expected.to run.with_params('', 'two').and_return('two') }
+  it { is_expected.to run.with_params(:undef, 'two').and_return('two') }
+  it { is_expected.to run.with_params(:undefined, 'two').and_return('two') }
+  it { is_expected.to run.with_params(nil, 'two').and_return('two') }
 end