2 files changed, 9 insertions, 1 deletions
diff --git a/cmdtest b/cmdtest
index 581b07a..b8c6efa 100755
--- a/cmdtest
+++ b/cmdtest
@@ -209,7 +209,8 @@ class CommandTester(cliapp.Application):
         argv = ['diff', '-u', expected_name, actual_name]
         with open(diff_name, 'w') as f:
             exit, out, err = self.runcmd_unchecked(argv, stdout=f)
-        return out
+        with open(diff_name, 'r') as f:
+            return f.read()
 
     def report_timings(self):
 
diff --git a/setup.py b/setup.py
index 3b06249..108841a 100644
--- a/setup.py
+++ b/setup.py
@@ -65,6 +65,13 @@ class Check(Command):
         subprocess.check_call(['./cmdtest', 'echo-tests'])
         subprocess.check_call(['./cmdtest', 'sort-tests'])
 
+        try:
+            subprocess.check_call(['./cmdtest', 'fail-tests'])
+        except subprocess.CalledProcessError:
+            pass
+        else:
+            raise Exception('fail-tests did not fail, which is a surprise')
+
 
 setup(name='cmdtest',
       version=cmdtestlib.__version__,