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, 26 deletions

diff --git a/spec/functions/is_float_spec.rb b/spec/functions/is_float_spec.rb
index d926634..ffff971 100755
--- a/spec/functions/is_float_spec.rb
+++ b/spec/functions/is_float_spec.rb
@@ -1,33 +1,22 @@
-#! /usr/bin/env ruby -S rspec
 require 'spec_helper'
 
-describe "the is_float function" do
-  let(:scope) { PuppetlabsSpec::PuppetInternals.scope }
+describe 'is_float' 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 { is_expected.to run.with_params(0.1, 0.2).and_raise_error(Puppet::ParseError, /wrong number of arguments/i) }
 
-  it "should exist" do
-    expect(Puppet::Parser::Functions.function("is_float")).to eq("function_is_float")
+  describe 'passing a string' do
+    it { is_expected.to run.with_params('0.1').and_return(true) }
+    it { is_expected.to run.with_params('1.0').and_return(true) }
+    it { is_expected.to run.with_params('1').and_return(false) }
+    it { is_expected.to run.with_params('one').and_return(false) }
+    it { is_expected.to run.with_params('one 1.0').and_return(false) }
+    it { is_expected.to run.with_params('1.0 one').and_return(false) }
   end
 
-  it "should raise a ParseError if there is less than 1 arguments" do
-    expect { scope.function_is_float([]) }.to( raise_error(Puppet::ParseError))
-  end
-
-  it "should return true if a float" do
-    result = scope.function_is_float(["0.12"])
-    expect(result).to(eq(true))
-  end
-
-  it "should return false if a string" do
-    result = scope.function_is_float(["asdf"])
-    expect(result).to(eq(false))
-  end
-
-  it "should return false if an integer" do
-    result = scope.function_is_float(["3"])
-    expect(result).to(eq(false))
-  end
-  it "should return true if a float is created from an arithmetical operation" do
-    result = scope.function_is_float([3.2*2])
-    expect(result).to(eq(true))
+  describe 'passing numbers' do
+    it { is_expected.to run.with_params(0.1).and_return(true) }
+    it { is_expected.to run.with_params(1.0).and_return(true) }
+    it { is_expected.to run.with_params(1).and_return(false) }
   end
 end