Automatic release update warnings. (#1336)

* Hide pretty help

* Automatic release update warnings.

* `httpie cli check-updates`

* adapt to the new loglevel construct

* Don't make the pie-colors the bold

* Apply review feedback.

Co-authored-by: Jakub Roztocil <jakub@roztocil.co>

tests/utils/__init__.py

@@ -49,6 +49,10 @@ HTTP_OK_COLOR = (
 DUMMY_URL = 'http://this-should.never-resolve'  # Note: URL never fetched
 DUMMY_HOST = url_as_host(DUMMY_URL)
 
+# We don't want hundreds of subprocesses trying to access GitHub API
+# during the tests.
+Config.DEFAULTS['disable_update_warnings'] = True
+
 
 def strip_colors(colorized_msg: str) -> str:
     return COLOR_RE.sub('', colorized_msg)
@@ -163,6 +167,7 @@ class MockEnvironment(Environment):
         self._delete_config_dir = True
 
     def cleanup(self):
+        self.devnull.close()
         self.stdout.close()
         self.stderr.close()
         warnings.resetwarnings()
@@ -179,6 +184,11 @@ class MockEnvironment(Environment):
             pass
 
 
+class PersistentMockEnvironment(MockEnvironment):
+    def cleanup(self):
+        pass
+
+
 class BaseCLIResponse:
     """
     Represents the result of simulated `$ http' invocation via `http()`.
@@ -442,7 +452,4 @@ def http(
         return r
 
     finally:
-        devnull.close()
-        stdout.close()
-        stderr.close()
         env.cleanup()