typing: Remove now-unnecessary conditional import.

As a result of dropping support for trusty, we can remove our old
pattern of putting `if False` before importing the typing module,
which was essential for Python 3.4 support, but not required and maybe
harmful on newer versions.

cron_file_helper
check_rabbitmq_consumers
hash_reqs
check_zephyr_mirror
check_personal_zephyr_mirrors
check_cron_file
zulip_tools
check_postgres_replication_lag
api_test_helpers
purge-old-deployments
setup_venv
node_cache
clean_venv_cache
clean_node_cache
clean_emoji_cache
pg_backup_and_purge
restore-backup
generate_secrets
zulip-ec2-configure-interfaces
diagnose
check_user_zephyr_mirror_liveness

docs/testing/mypy.md

@@ -95,36 +95,6 @@ an `Any` or `# type: ignore` so you're not blocked waiting for help,
 add a `# TODO: ` comment so it doesn't get forgotten in code review,
 and ask for help in chat.zulip.org.
 
-## mypy in production scripts
-
-While in most of the Zulip codebase, we can consistently use the
-`typing` module (Part of the standard library in Python 3.5, but
-present as an installable module with older Python), in our installer
-and other production scripts that might run outside a Zulip
-virtualenv, we cannot rely on the `typing` module being present on the
-system.
-
-To solve this problem, we use the following (semi-standard in the mypy
-community) hack in those scripts:
-
-```
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import List
-```
-
-and then use the Python 2 style type comment syntax for annotating
-those files.  This way, the Python interpreters for Python 2.7 and 3.4
-will ignore this line, and thus not crash.  But we can still get all
-the benefits of type annotations in that codebase, since the `mypy`
-type checker ignores the `if False` and thus still is able to
-type-check the file using those imports.
-
-The exception to this rule is that any scripts which use
-`setup_path_on_import` before they import from the `typing` module are
-safe.  These, we generally declare in the relevant exclude line in
-`tools/linter_lib/custom_check.py`
-
 ## mypy stubs for third-party modules.
 
 For the Python standard library and some popular third-party modules,

puppet/zulip/files/nagios_plugins/zulip_app_frontend/check_cron_file

@@ -4,10 +4,7 @@ file output by the cron job is correct.
 """
 import sys
 import time
-
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Tuple
+from typing import Tuple
 
 def nagios_from_file(results_file: str, max_time_diff: int=60 * 2) -> 'Tuple[int, str]':
     """Returns a nagios-appropriate string and return code obtained by

puppet/zulip/files/nagios_plugins/zulip_nagios_server/check_postgres_replication_lag

@@ -4,13 +4,12 @@
 Nagios plugin to check the difference between the primary and
 secondary Postgres servers' xlog location.
 """
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from mypy_extensions import NoReturn
 
 import subprocess
 import re
 
+from mypy_extensions import NoReturn
+
 states = {
     "OK": 0,
     "WARNING": 1,

puppet/zulip/files/postgresql/pg_backup_and_purge

@@ -10,8 +10,7 @@ import dateutil.parser
 import pytz
 import time
 from datetime import datetime, timedelta
-if False:
-    from typing import Dict, List
+from typing import Dict, List
 
 logging.Formatter.converter = time.gmtime
 logging.basicConfig(format="%(asctime)s %(levelname)s: %(message)s")

puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_personal_zephyr_mirrors

@@ -8,10 +8,7 @@ This script works by just monitoring the files under
 mirrors when they receive the messages sent every minute by
 /etc/cron.d/test_zephyr_personal_mirrors
 """
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Dict
-
+from typing import Dict
 import os
 import time
 

puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_user_zephyr_mirror_liveness

@@ -24,9 +24,7 @@ django.setup()
 
 from zerver.models import UserActivity
 
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Any, Dict, Set, Optional
+from typing import Any, Dict, Set, Optional
 
 states = {
     "OK": 0,

puppet/zulip_ops/files/nagios_plugins/zulip_zephyr_mirror/check_zephyr_mirror

@@ -9,10 +9,7 @@ run out of cron.
 
 See puppet/zulip_ops/files/cron.d/zephyr-mirror for the crontab details.
 """
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Dict
-
+from typing import Dict
 import os
 import time
 

puppet/zulip_ops/files/zulip-ec2-configure-interfaces

@@ -50,9 +50,8 @@ import subprocess
 
 import boto.utils
 import netifaces
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Optional
+
+from typing import Optional
 
 def address_of(device_id):
     # type: (int) -> Optional[str]

scripts/lib/clean_emoji_cache.py

@@ -3,9 +3,7 @@ import argparse
 import os
 import sys
 
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Set
+from typing import Set
 
 ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 sys.path.append(ZULIP_PATH)

scripts/lib/clean_node_cache.py

@@ -4,9 +4,7 @@ import os
 import subprocess
 import sys
 
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Set
+from typing import Set
 
 ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 sys.path.append(ZULIP_PATH)

scripts/lib/clean_venv_cache.py

@@ -3,9 +3,7 @@ import argparse
 import os
 import sys
 
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Set
+from typing import Set
 
 ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 sys.path.append(ZULIP_PATH)

scripts/lib/hash_reqs.py

@@ -3,10 +3,7 @@ import os
 import sys
 import argparse
 import hashlib
-
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Iterable, List, MutableSet
+from typing import Iterable, List, MutableSet
 
 def expand_reqs_helper(fpath, visited):
     # type: (str, MutableSet[str]) -> List[str]

scripts/lib/node_cache.py

@@ -3,10 +3,7 @@ import os
 import hashlib
 import json
 
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Optional, List, IO, Any
-
+from typing import Optional, List, IO, Any
 from scripts.lib.zulip_tools import subprocess_text_output, run
 
 ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

scripts/lib/setup_venv.py

@@ -7,6 +7,8 @@ import sys
 from scripts.lib.zulip_tools import run, run_as_root, ENDC, WARNING
 from scripts.lib.hash_reqs import expand_reqs
 
+from typing import List, Optional, Tuple, Set
+
 ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 VENV_CACHE_PATH = "/srv/zulip-venv-cache"
 
@@ -14,10 +16,6 @@ if 'TRAVIS' in os.environ:
     # In Travis CI, we don't have root access
     VENV_CACHE_PATH = "/home/travis/zulip-venv-cache"
 
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import List, Optional, Tuple, Set
-
 VENV_DEPENDENCIES = [
     "build-essential",
     "libffi-dev",

scripts/lib/zulip_tools.py

@@ -16,9 +16,7 @@ import json
 import uuid
 import configparser
 
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Sequence, Set, Any, Dict, List
+from typing import Sequence, Set, Any, Dict, List
 
 DEPLOYMENTS_DIR = "/home/zulip/deployments"
 LOCK_DIR = os.path.join(DEPLOYMENTS_DIR, "lock")

scripts/nagios/check-rabbitmq-consumers

@@ -7,10 +7,7 @@ import configparser
 from collections import defaultdict
 import os
 import subprocess
-
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Dict
+from typing import Dict
 
 states = {
     0: "OK",

scripts/nagios/cron_file_helper.py

@@ -1,8 +1,6 @@
 import time
 
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Tuple
+from typing import Tuple
 
 def nagios_from_file(results_file):
     # type: (str) -> Tuple[int, str]

scripts/purge-old-deployments

@@ -4,9 +4,7 @@ import os
 import subprocess
 import sys
 
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Set
+from typing import Set
 
 ZULIP_PATH = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 sys.path.append(ZULIP_PATH)

scripts/setup/generate_secrets.py

@@ -3,9 +3,8 @@
 
 import sys
 import os
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Dict, List
+
+from typing import Dict, List
 
 BASE_DIR = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 sys.path.append(BASE_DIR)

scripts/setup/restore-backup

@@ -7,8 +7,7 @@ import subprocess
 import sys
 import tempfile
 
-if False:
-    from typing import IO
+from typing import IO
 
 BASE_DIR = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 sys.path.append(BASE_DIR)

tools/diagnose

@@ -6,9 +6,7 @@ import shlex
 import sys
 import subprocess
 
-if False:
-    # See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts
-    from typing import Callable, List
+from typing import Callable, List
 
 TOOLS_DIR = os.path.dirname(__file__)
 ROOT_DIR = os.path.dirname(TOOLS_DIR)

tools/linter_lib/custom_check.py

@@ -330,21 +330,6 @@ python_rules = RuleList(
          'description': 'Most scripts are intended to run on systems without sudo.',
          'good_lines': ['subprocess.check_call(["ls"])'],
          'bad_lines': ['subprocess.check_call(["sudo", "ls"])']},
-        {'pattern': '^from typing import',
-         'strip': '\n',
-         'include_only': set([
-             'scripts/',
-             'puppet/',
-         ]),
-         'exclude': set([
-             # Not important, but should fix
-             'scripts/lib/process-mobile-i18n',
-             # Uses setup_path_on_import before importing.
-             'puppet/zulip/files/nagios_plugins/zulip_app_frontend/check_send_receive_time',
-         ]),
-         'description': 'For scripts run as part of installer, cannot rely on typing existing; use `if False` workaround.',
-         'good_lines': ['    from typing import List'],
-         'bad_lines': ['from typing import List']},
         {'pattern': 'django.utils.translation',
          'include_only': set(['test/', 'zerver/views/development/']),
          'description': 'Test strings should not be tagged for translation',
@@ -798,10 +783,6 @@ markdown_rules = RuleList(
          'description': 'Linkified markdown URLs should use cleaner <http://example.com> syntax.'},
         {'pattern': 'https://zulip.readthedocs.io/en/latest/[a-zA-Z0-9]',
          'exclude': ['docs/overview/contributing.md', 'docs/overview/readme.md', 'docs/README.md'],
-         'exclude_line': set([
-             ('docs/testing/mypy.md',
-              '# See https://zulip.readthedocs.io/en/latest/testing/mypy.html#mypy-in-production-scripts')
-         ]),
          'include_only': set(['docs/']),
          'description': "Use relative links (../foo/bar.html) to other documents in docs/",
          },

zerver/lib/api_test_helpers.py

@@ -6,8 +6,7 @@ import os
 from zerver.lib import mdiff
 from zerver.lib.openapi import validate_against_openapi_schema
 
-if False:
-    from zulip import Client
+from zulip import Client
 
 ZULIP_DIR = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 FIXTURE_PATH = os.path.join(ZULIP_DIR, 'templates', 'zerver', 'api', 'fixtures.json')