diff --git a/test/test_blob.rb b/test/test_blob.rb
index aba82084..fc9e13c5 100644
--- a/test/test_blob.rb
+++ b/test/test_blob.rb
@@ -140,6 +140,13 @@ class TestBlob < Test::Unit::TestCase
     assert !blob("Perl/script.pl").binary?
   end
 
+  def test_all_binary
+    Samples.each do |sample|
+      blob = blob(sample[:path])
+      assert ! (blob.likely_binary? || blob.binary?), "#{sample[:path]} is a binary file"
+    end
+  end
+
   def test_text
     assert blob("Text/README").text?
     assert blob("Text/dump.sql").text?