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, 11 insertions, 24 deletions

diff --git a/spec/functions/flatten_spec.rb b/spec/functions/flatten_spec.rb
index de8c66d..a4338be 100755
--- a/spec/functions/flatten_spec.rb
+++ b/spec/functions/flatten_spec.rb
@@ -1,27 +1,14 @@
-#! /usr/bin/env ruby -S rspec
 require 'spec_helper'
 
-describe "the flatten function" do
-  let(:scope) { PuppetlabsSpec::PuppetInternals.scope }
-  it "should exist" do
-    expect(Puppet::Parser::Functions.function("flatten")).to eq("function_flatten")
-  end
-
-  it "should raise a ParseError if there is less than 1 arguments" do
-    expect { scope.function_flatten([]) }.to( raise_error(Puppet::ParseError))
-  end
-
-  it "should raise a ParseError if there is more than 1 argument" do
-    expect { scope.function_flatten([[], []]) }.to( raise_error(Puppet::ParseError))
-  end
-
-  it "should flatten a complex data structure" do
-    result = scope.function_flatten([["a","b",["c",["d","e"],"f","g"]]])
-    expect(result).to(eq(["a","b","c","d","e","f","g"]))
-  end
-
-  it "should do nothing to a structure that is already flat" do
-    result = scope.function_flatten([["a","b","c","d"]])
-    expect(result).to(eq(["a","b","c","d"]))
-  end
+describe 'flatten' do
+  it { is_expected.not_to eq(nil) }
+  it { is_expected.to run.with_params().and_raise_error(Puppet::ParseError) }
+  it { is_expected.to run.with_params([], []).and_raise_error(Puppet::ParseError) }
+  it { is_expected.to run.with_params(1).and_raise_error(Puppet::ParseError) }
+  it { is_expected.to run.with_params('one').and_raise_error(Puppet::ParseError) }
+  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(["a","b","c","d","e","f","g"]).and_return(["a","b","c","d","e","f","g"]) }
+  it { is_expected.to run.with_params([["a","b",["c",["d","e"],"f","g"]]]).and_return(["a","b","c","d","e","f","g"]) }
 end