patchpal: make testing work on linux via Xvfb

Signed-off-by: Jarod Wilson <[email protected]>

Author: jarodwilson

Formula/p/patchpal.rb

@@ -20,6 +20,10 @@ class Patchpal < Formula
   depends_on "llvm"
   depends_on "pango"
 
+  on_linux do
+    depends_on "xorg-server" => :test
+  end
+
   def install
     ENV.prepend_path "PATH", Formula["gawk"].bin if OS.mac?
     inreplace "tests/run.sh", "readlink -e", "echo"
@@ -35,7 +39,13 @@ def install
     ENV["GIT_AUTHOR_EMAIL"] = "[email protected]"
     ENV["GIT_COMMITTER_NAME"] = "A Developer"
     ENV["GIT_COMMITTER_EMAIL"] = "[email protected]"
-    ENV["DISPLAY"] = ":0"
+
+    if OS.linux?
+      xvfb_pid = spawn Formula["xorg-server"].bin/"Xvfb", ":1"
+      ENV["DISPLAY"] = ":1"
+      sleep 10
+    end
+
     output = shell_output("#{prefix}/tests/run.sh -v")
     assert_match <<~EOS, output
       ok 1 test_add_copied.sh
@@ -52,4 +62,8 @@ def install
       1..11
     EOS
   end
+
+  ensure
+    Process.kill("TERM", xvfb_pid) if xvfb_pid
+  end
 end