diff --git a/spec/samples_run_spec.rb b/spec/samples_run_spec.rb
index 281e500..a7ed09c 100644
--- a/spec/samples_run_spec.rb
+++ b/spec/samples_run_spec.rb
@@ -5,6 +5,32 @@ describe Squib do
 
   context "all samples" do
 
+    FILE_HASHES = {
+      "basic_" => "2a35fa3bb121fe188c44d9b73cb7dcd3",
+      "colors_" => "8917ed746d12b5d8bdc971415913a286",
+      "layout_" => "4645a9cc0dc39d7ea673edafe9d8d30d",
+      "load_images_" => "1e01c021c05d9b31568b01657c176b0b",
+      "ranges_" => "614e439da81923df2b6e2458e5b389e3",
+      "sample-save-pdf" => "d83a01103fa9e1e75706e2156d8f74ab",
+      "sample_excel_" => "7aacc3f82073302aba698660f912ee40",
+      "shape_" => "fb7669f3c301db05985ce54aea839460",
+      "text_" => "ea924a806bda2f39ed5becb9c6c911b7",
+      "tgc_sample_" => "dce2d03e0ea0647f9ec635ab601a4651",
+      "units_" => "bc251c1858c6c821ae06415279a02f62"
+    }
+
+    def hashes_of(dir, file_prefixes)
+      map = {}
+      file_prefixes.each do |pre|
+        hash = ""
+        Dir["#{dir}/#{pre}*"].each do |file|
+          hash += Digest::MD5.hexdigest(File.read(file))   
+        end
+        map[pre] = Digest::MD5.hexdigest(hash)
+      end
+      map
+    end
+
     it "should execute with no errors" do
       samples = File.expand_path('../samples', File.dirname(__FILE__))
       Dir["#{samples}/**/*.rb"].each do |sample|
@@ -12,6 +38,7 @@ describe Squib do
           require_relative "../samples/#{File.basename(sample)}"
         end
       end
+      expect(hashes_of("#{samples}/_output", FILE_HASHES.keys)).to eq(FILE_HASHES)
     end
 
   end