Show data in test_httpbin.

tests/integration/test_webserver.py

@@ -1,4 +1,5 @@
 import urllib.request
+import urllib.error
 
 import pytest
 
@@ -12,7 +13,15 @@ import pytest
 def test_httpbin(httpbin, qtbot, path, content, expected):
     with qtbot.waitSignal(httpbin.got_new_url, raising=True, timeout=100):
         url = 'http://localhost:{}{}'.format(httpbin.port, path)
-        response = urllib.request.urlopen(url)
+        try:
+            response = urllib.request.urlopen(url)
+        except urllib.error.HTTPError as e:
+            # "Though being an exception (a subclass of URLError), an HTTPError
+            # can also function as a non-exceptional file-like return value
+            # (the same thing that urlopen() returns)."
+            # ...wat
+            print(e.read().decode('utf-8'))
+            raise
 
     data = response.read().decode('utf-8')