DEV: Add Ember CLI tests workflow (#12474)

.github/workflows/ember.yml

@@ -0,0 +1,47 @@
+name: Ember CLI tests
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - main
+
+jobs:
+  build:
+    name: run
+    runs-on: ubuntu-latest
+    container: discourse/discourse_test:release
+    timeout-minutes: 40
+
+    steps:
+      - uses: actions/checkout@master
+        with:
+          fetch-depth: 1
+
+      - name: Setup Git
+        run: |
+          git config --global user.email "ci@ci.invalid"
+          git config --global user.name "Discourse CI"
+
+      - name: Get yarn cache directory
+        id: yarn-cache-dir
+        run: echo "::set-output name=dir::$(yarn cache dir)"
+
+      - name: Yarn cache
+        uses: actions/cache@v2
+        id: yarn-cache
+        with:
+          path: ${{ steps.yarn-cache-dir.outputs.dir }}
+          key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-yarn-
+
+      - name: Yarn install
+        working-directory: ./app/assets/javascripts/discourse
+        run: yarn install
+
+      - name: Core QUnit
+        working-directory: ./app/assets/javascripts/discourse
+        run: yarn ember test
+        timeout-minutes: 30