fix(tests): return code, after SIGTERM received, is -15, not 0.

related: #1

--HG--
branch : 3.27

cubicweb/devtools/qunit.py

@@ -96,8 +96,11 @@ class FirefoxHelper(object):
             assert self._process.returncode is None, self._process.returncode
             self._process.terminate()
             self._process.wait()
-            assert self._process.returncode == 0, "Error: firefox return code is %s, see %s" %\
-                                                  (self._process.returncode, self.log_file)
+            # terminate() sends the signal SIGTERM to the process, which has
+            # value 15, therefore the returncode should be -15.
+            # https://docs.python.org/3/library/subprocess.html#subprocess.CompletedProcess.returncode
+            assert self._process.returncode == -15, "Error: firefox return code is %s, see %s" %\
+                                                    (self._process.returncode, self.log_file)
             self._process = None
 
     def __del__(self):