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, 15 insertions, 15 deletions

diff --git a/spec/functions/join_spec.rb b/spec/functions/join_spec.rb
index 793c36f..a300571 100755
--- a/spec/functions/join_spec.rb
+++ b/spec/functions/join_spec.rb
@@ -1,19 +1,19 @@
-#! /usr/bin/env ruby -S rspec
 require 'spec_helper'
 
-describe "the join function" do
-  let(:scope) { PuppetlabsSpec::PuppetInternals.scope }
+describe 'join' do
+  it { is_expected.not_to eq(nil) }
+  it { is_expected.to run.with_params().and_raise_error(Puppet::ParseError, /wrong number of arguments/i) }
+  it {
+    pending("Current implementation ignores parameters after the second.")
+    is_expected.to run.with_params([], '', '').and_raise_error(Puppet::ParseError, /wrong number of arguments/i)
+  }
+  it { is_expected.to run.with_params('one').and_raise_error(Puppet::ParseError, /Requires array to work with/) }
+  it { is_expected.to run.with_params([], 2).and_raise_error(Puppet::ParseError, /Requires string to work with/) }
 
-  it "should exist" do
-    expect(Puppet::Parser::Functions.function("join")).to eq("function_join")
-  end
-
-  it "should raise a ParseError if there is less than 1 arguments" do
-    expect { scope.function_join([]) }.to( raise_error(Puppet::ParseError))
-  end
-
-  it "should join an array into a string" do
-    result = scope.function_join([["a","b","c"], ":"])
-    expect(result).to(eq("a:b:c"))
-  end
+  it { is_expected.to run.with_params([]).and_return('') }
+  it { is_expected.to run.with_params([], ':').and_return('') }
+  it { is_expected.to run.with_params(['one']).and_return('one') }
+  it { is_expected.to run.with_params(['one'], ':').and_return('one') }
+  it { is_expected.to run.with_params(['one', 'two', 'three']).and_return('onetwothree') }
+  it { is_expected.to run.with_params(['one', 'two', 'three'], ':').and_return('one:two:three') }
 end