1 files changed, 18 insertions, 2 deletions
diff --git a/Library/Formula/newick-utils.rb b/Library/Formula/newick-utils.rb
index d201990ad..82df8e114 100644
--- a/Library/Formula/newick-utils.rb
+++ b/Library/Formula/newick-utils.rb
@@ -18,8 +18,24 @@ class NewickUtils < Formula
     system "make install"
   end
 
-  def test
-    system "echo '(B:1,C:2)A;' | #{bin}/nw_display -"
+  test do
+    require 'open3'
+
+    expected = <<-EOS
+ +-------------------------------------+ B
+=| A
+ +---------------------------------------------------------------------------+ C
+
+ |------------------|------------------|------------------|------------------|
+ 0                0.5                  1                1.5                  2
+ substitutions/site
+EOS
+
+    Open3.popen3("#{bin}/nw_display", "-") do |stdin, stdout, _|
+      stdin.write("(B:1,C:2)A;\n")
+      stdin.close
+      expected == stdout.read.split("\n").map(&:rstrip).join("\n")
+    end
   end
 end