1 files changed, 19 insertions, 0 deletions
diff --git a/puppet/modules/stdlib/spec/functions/difference_spec.rb b/puppet/modules/stdlib/spec/functions/difference_spec.rb
new file mode 100755
index 00000000..24b2b1bc
--- /dev/null
+++ b/puppet/modules/stdlib/spec/functions/difference_spec.rb
@@ -0,0 +1,19 @@
+#! /usr/bin/env ruby -S rspec
+require 'spec_helper'
+
+describe "the difference function" do
+  let(:scope) { PuppetlabsSpec::PuppetInternals.scope }
+
+  it "should exist" do
+    expect(Puppet::Parser::Functions.function("difference")).to eq("function_difference")
+  end
+
+  it "should raise a ParseError if there are fewer than 2 arguments" do
+    expect { scope.function_difference([]) }.to( raise_error(Puppet::ParseError) )
+  end
+
+  it "should return the difference between two arrays" do
+    result = scope.function_difference([["a","b","c"],["b","c","d"]])
+    expect(result).to(eq(["a"]))
+  end
+end