Rakefile in lamby-4.1.1 vs Rakefile in lamby-4.2.0

@@ -3,10 +3,16 @@
 require "rake/testtask"
 
 Rake::TestTask.new(:test) do |t|
   t.libs << "test"
   t.libs << "lib"
-  t.test_files = FileList["test/**/*_test.rb"]
+  t.test_files = begin
+    if ENV['TEST_FILE']
+      [ENV['TEST_FILE']]
+    else
+      FileList["test/**/*_test.rb"]
+    end
+  end
   t.verbose = false
   t.warning = false
 end
 
 Rake::TestTask.new(:test_deflate) do |t|