Merge pull request #548 from modcloth/mbh/backtick-process-status

Kernel#` sets $?

lib-topaz/kernel.rb

@@ -45,7 +45,12 @@ def loop
   def `(cmd)
     cmd = cmd.to_str if cmd.respond_to?(:to_str)
     raise TypeError.new("can't convert #{cmd.class} into String") unless cmd.is_a?(String)
-    IO.popen(cmd) { |r| r.read }
+    res = ''
+    IO.popen(cmd) do |r|
+      res << r.read
+      Process.waitpid(r.pid)
+    end
+    res
   end
 
   def to_enum(method = :each, *args)

lib-topaz/process.rb

@@ -18,6 +18,12 @@ def initialize(pid, exitstatus)
       @exitstatus = exitstatus
     end
 
+    def success?
+      @exitstatus == 0
+    end
+
+    alias exited? success?
+
     def pid
       @pid
     end

tests/modules/test_kernel.py

@@ -265,6 +265,14 @@ def test_backtick(self, space):
         w_res = space.execute("return `echo 10`")
         assert self.unwrap(space, w_res) == "10\n"
 
+    def test_backtick_sets_process_status(self, space):
+        w_res = space.execute("""
+        $? = nil
+        `echo`
+        return $?.class.name
+        """)
+        assert self.unwrap(space, w_res) == "Process::Status"
+
 
 class TestRequire(BaseTopazTest):
     def test_simple(self, space, tmpdir):