nginx: skip frontend build in tests

This significantly decreases test turnaround time.

Local results (`./run-tests; time ./run-tests.sh`):

* with this PR: 14 seconds
* without this: 90 seconds

Cons:

* complicates build script (`build-frontend.sh`)

files/prebuild/build-frontend.sh

@@ -1,4 +1,18 @@
 #!/bin/bash -eu
+
 cd client
-npm clean-install --no-audit --fund=false --update-notifier=false
-npm run build
+
+if [[ ${SKIP_FRONTEND_BUILD-} != "" ]]; then
+  echo "[build-frontend] Skipping frontend build."
+
+  # Create minimal fake frontend to allow tests to pass:
+  mkdir -p dist
+  echo > dist/blank.html
+  echo > dist/favicon.ico
+  echo > dist/index.html '<div id="app"></div>'
+
+  exit
+else
+  npm clean-install --no-audit --fund=false --update-notifier=false
+  npm run build
+fi

nginx.dockerfile

@@ -8,6 +8,8 @@ RUN apt-get update \
 
 COPY ./ ./
 RUN files/prebuild/write-version.sh
+
+ARG SKIP_FRONTEND_BUILD
 RUN files/prebuild/build-frontend.sh
 
 

test/nginx.test.docker-compose.yml

@@ -17,6 +17,8 @@ services:
     build:
       context: ..
       dockerfile: nginx.dockerfile
+      args:
+        SKIP_FRONTEND_BUILD: true
     depends_on:
       - service
       - enketo