Add check for a missing make extract_translations

Forgetting to run that causes weblate (or other translation tools) to
show outdated strings and not import new strings, which is bad for the
collaboration.

Fixes #118.

.github/workflows/main.yaml

@@ -50,6 +50,29 @@ jobs:
         run: |
           python -m flake8 snikket_web
 
+  translation-check:
+    runs-on: ubuntu-latest
+
+    name: 'lint: i18n'
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+        with:
+          python-version: '3.9'
+      - name: Install
+        run: |
+          set -euo pipefail
+          pip install flask-babel
+      - name: Linting
+        run: |
+          sed -ri '/^"POT-Creation-Date: /d' snikket_web/translations/messages.pot
+          git add snikket_web/translations/messages.pot
+          make extract_translations
+          sed -ri '/^"POT-Creation-Date: /d' snikket_web/translations/messages.pot
+          git diff --exit-code --color -- snikket_web/translations/messages.pot
+
+
   build:
     runs-on: ubuntu-latest
 

snikket_web/infra.py

@@ -8,7 +8,6 @@ import quart.flask_patch  # noqa:F401
 from quart import (
     current_app,
     request,
-    g,
 )
 
 import flask_babel
@@ -35,9 +34,6 @@ BYTE_UNIT_SCALE_MAP = [
 
 @babel.localeselector  # type:ignore
 def selected_locale() -> str:
-    # Needs mypy ignore because this is a free-for-all object and has no
-    # publicly known attributes.
-    g.language_header_accessed = True  # type: ignore
     selected = request.accept_languages.best_match(
         current_app.config['LANGUAGES']
     ) or current_app.config['LANGUAGES'][0]
@@ -72,12 +68,6 @@ def format_bytes(n: float) -> str:
     return "{} {}".format(n, unit)
 
 
-def add_vary_language_header(resp: quart.Response) -> quart.Response:
-    if getattr(g, "language_header_accessed", False):
-        resp.vary.add("Accept-Language")
-    return resp
-
-
 def init_templating(app: quart.Quart) -> None:
     app.template_filter("repr")(repr)
     app.template_filter("format_datetime")(flask_babel.format_datetime)
@@ -88,7 +78,6 @@ def init_templating(app: quart.Quart) -> None:
     app.template_filter("format_bytes")(format_bytes)
     app.template_filter("flatten")(flatten)
     app.template_filter("circle_name")(circle_name)
-    app.after_request(add_vary_language_header)
 
 
 def generate_error_id() -> str: