run grist-core test batches in parallel (#444)

This sets up a framework for running tests in parallel.
It increases the total time taken (since some steps are
repeated) but reduces the turn-around time significantly
overall.

The main objective is to make it possible to release more
test batches to grist-core without bringing CI to a crawl.

The clever little test/split-test.js script is from the
Grist Labs mono-repo and is Dmitry's work.

I considered doing the build in one job, and copying
it to test jobs, since it feels wasteful to repeat it.
That may be worth trying, especially if we start getting
jobs backing up (total concurrent Linux jobs on free plan
is quoted at 20).

It might also be worth looking at doing some tests in
parallel on the same worker, perhaps using the relatively
new MOCHA_WORKER_ID feature, since the tests are often not
actually CPU or I/O bound.

.github/workflows/main.yml

@@ -10,24 +10,35 @@ on:
   workflow_dispatch:
 
 jobs:
-  build:
+  build_and_test:
     runs-on: ubuntu-latest
     strategy:
       matrix:
         python-version: [3.9]
         node-version: [14.x]
+        tests:
+          - ':lint:python:client:common:smoke:'
+          - ':server-1-of-2:'
+          - ':server-2-of-2:'
+          - ':nbrowser-1-of-5:'
+          - ':nbrowser-2-of-5:'
+          - ':nbrowser-3-of-5:'
+          - ':nbrowser-4-of-5:'
+          - ':nbrowser-5-of-5:'
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v1
+        uses: actions/setup-node@v3
         with:
           node-version: ${{ matrix.node-version }}
+          cache: 'yarn'
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
+          cache: 'pip'
 
       - name: Install Python packages
         run: |
@@ -38,9 +49,11 @@ jobs:
         run: yarn install
 
       - name: Run eslint
+        if: contains(matrix.tests, ':lint:')
         run: yarn run lint:ci
 
       - name: Make sure bucket is versioned
+        if: contains(matrix.tests, ':server-')
         env:
           AWS_ACCESS_KEY_ID: administrator
           AWS_SECRET_ACCESS_KEY: administrator
@@ -49,15 +62,27 @@ jobs:
       - name: Build Node.js code
         run: yarn run build:prod
 
-
       - name: Run smoke test
+        if: contains(matrix.tests, ':smoke:')
         run: VERBOSE=1 DEBUG=1 MOCHA_WEBDRIVER_HEADLESS=1 yarn run test:smoke
 
       - name: Run python tests
+        if: contains(matrix.tests, ':python:')
         run: yarn run test:python
 
+      - name: Run client tests
+        if: contains(matrix.tests, ':client:')
+        run: yarn run test:client
+
+      - name: Run common tests
+        if: contains(matrix.tests, ':common:')
+        run: yarn run test:common
+
       - name: Run server tests with minio and redis
-        run: MOCHA_WEBDRIVER_HEADLESS=1 yarn run test:server
+        if: contains(matrix.tests, ':server-')
+        run: |
+          export TEST_SPLITS=$(echo $TESTS | sed "s/.*:server-\([^:]*\).*/\1/")
+          MOCHA_WEBDRIVER_HEADLESS=1 yarn run test:server
         env:
           GRIST_DOCS_MINIO_ACCESS_KEY: administrator
           GRIST_DOCS_MINIO_SECRET_KEY: administrator
@@ -68,15 +93,12 @@ jobs:
           GRIST_DOCS_MINIO_BUCKET: grist-docs-test
 
       - name: Run main tests without minio and redis
-        run: MOCHA_WEBDRIVER_HEADLESS=1 yarn run test --exclude '_build/test/server/**/*'
-
-      - name: Update candidate branch
-        if: ${{ github.event_name == 'push' }}
-        uses: ad-m/github-push-action@8407731efefc0d8f72af254c74276b7a90be36e1
-        with:
-          github_token: ${{ secrets.GITHUB_TOKEN }}
-          branch: latest_candidate
-          force: true
+        if: contains(matrix.tests, ':nbrowser-')
+        run: |
+          export TEST_SPLITS=$(echo $TESTS | sed "s/.*:nbrowser-\([^:]*\).*/\1/")
+          MOCHA_WEBDRIVER_HEADLESS=1 yarn run test:nbrowser
+        env:
+          TESTS: ${{ matrix.tests }}
 
     services:
       # https://github.com/bitnami/bitnami-docker-minio/issues/16
@@ -103,3 +125,18 @@ jobs:
           --health-interval 10s
           --health-timeout 5s
           --health-retries 5
+
+  candidate:
+    needs: build_and_test
+    if: ${{ success() && github.event_name == 'push' }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Fetch new candidate branch
+        uses: actions/checkout@v3
+
+      - name: Update candidate branch
+        uses: ad-m/github-push-action@8407731efefc0d8f72af254c74276b7a90be36e1
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          branch: latest_candidate
+          force: true