ci(github): revise github actions ci workflows

- [x] clean up workflows, add comments to justify suggestions;
- [x] implement a reusable workflow that might be used later, add explanatory comments;

.github/workflows/get-variables.yml

@@ -0,0 +1,37 @@
+# For more information see:
+# - https://docs.github.com/en/actions/using-workflows/reusing-workflows
+# - https://docs.github.com/en/actions/using-workflows/reusing-workflows#limitations
+
+# Note:
+# This workflow might be used after code is merged into the master branch.
+# The workflow is references in other workflows like: ngxs/store/.github/workflows/get-variables.yml@master
+
+name: get-variables
+
+on:
+  workflow_call:
+    outputs:
+      shortref:
+        description: "Branch name"
+        value: ${{ jobs.get-variables.outputs.shortref }}
+      commitsha:
+        description: "GitHub commit SHA"
+        value: ${{ jobs.get-variables.outputs.commitsha }}
+      yarncachedir:
+        description: "Yarn cache directory"
+        value: ${{ jobs.get-variables.outputs.yarncachedir }}
+
+jobs:
+  get-variables:
+    name: Get variables (branch name, commit hash, yarn cache directory)
+    runs-on: ubuntu-latest
+    outputs:
+      shortref: ${{ steps.get-variables.outputs.firstword }}
+      commitsha: ${{ steps.get-variables.outputs.secondword }}
+      yarncachedir: ${{ steps.get-variables.outputs.secondword }}
+    steps:
+      - id: get-variables
+        run: |
+          echo "::set-output name=shortref::${GITHUB_REF#refs/*/}";
+          echo "::set-output name=commitsha::$(echo ${GITHUB_SHA})";
+          echo "::set-output name=yarncachedir::$(yarn cache dir)";

.github/workflows/pr-validation.yml

@@ -16,8 +16,13 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  ## the reusable job will work after the PR is merged and files are committed to the master branch
+  # get-variables:
+  #   uses: ngxs/store/.github/workflows/get-variables.yml@master # <- references a reusable workflow file and a branch
+
   premerge:
     runs-on: ubuntu-latest
+    # needs: get-variables # this can be uncommented after the reusable job works (see above)
 
     strategy:
       matrix:
@@ -42,7 +47,8 @@ jobs:
       - name: Configure kernel (increase watchers)
         run: echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p
 
-      - name: Get variables (branch name, commit hash, yarn cache directory,)
+      # this step might be replaced with a reusable workflow get-variables.yml (see above)
+      - name: Get variables (branch name, commit hash, yarn cache directory)
         id: get-variables
         run: |
           echo "::set-output name=shortref::${GITHUB_REF#refs/*/}";
@@ -64,10 +70,18 @@ jobs:
             ${{ runner.os }}-node-${{ matrix.node-version }}-yarn-${{ hashFiles('**/yarn.lock') }}-branch-
             ${{ runner.os }}-node-${{ matrix.node-version }}-yarn-
             ${{ runner.os }}-
+          ## the above might be replaced with the commented code beneath if a reusable workflow get-variables.yml is used (see above)
+          # key: ${{ runner.os }}-node-${{ matrix.node-version }}-yarn-${{ hashFiles('**/yarn.lock') }}-branch-${{ needs.get-variables.outputs.shortref }}-workspace-${{ needs.get-variables.outputs.commitsha }}
+          # restore-keys: |
+          #   ${{ runner.os }}-node-${{ matrix.node-version }}-yarn-${{ hashFiles('**/yarn.lock') }}-branch-${{ needs.get-variables.outputs.shortref }}-workspace-
+          #   ${{ runner.os }}-node-${{ matrix.node-version }}-yarn-${{ hashFiles('**/yarn.lock') }}-branch-
+          #   ${{ runner.os }}-node-${{ matrix.node-version }}-yarn-
+          #   ${{ runner.os }}-
 
       - name: Install project dependencies
         run: yarn install --frozen-lockfile --non-interactive
 
+      # Is 'yarn pack --filename ./dist/ngxs-core.tgz' needed during premerge checks?
       - name: Compile NGXS and create a pack
         run: |
           yarn build
@@ -82,12 +96,15 @@ jobs:
       - name: Unit Tests
         run: yarn test:ci
 
+      ## This step was commented in the CircleCI workflows config.
       # - name: Integration Tests
       #   run: yarn test:ci:integration
 
+      ## This step was commented in the CircleCI workflows config.
       # - name: E2E Tests
       #   run: yarn test:ci:e2e
 
+      ## This step was commented in the CircleCI workflows config.
       # - name: Integration Tests - SSR
       #   run: yarn test:ci:integration:ssr
 
@@ -127,11 +144,14 @@ jobs:
       - name: Check the size of NGXS bundle
         run: yarn bundlesize
 
-      - name: Upload coverage results to Code Climate
-        run: |
-          curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > /tmp/cc-test-reporter
-          chmod +x /tmp/cc-test-reporter
-          /tmp/cc-test-reporter after-build --coverage-input-type lcov --exit-code 0
-        env:
-          CC_TEST_REPORTER_ID: 3f4c9a9d57ded045e0f9ab5d23e5bbcbf709bb85637bea555f1233e72134b818 # TODO: better store it in secrets. Name the variable: CC_TEST_REPORTER_ID. Then delete this line and uncomment the nest one
-          # CC_TEST_REPORTER_ID: ${{ secrets.CC_TEST_REPORTER_ID }}
+      ## Actually, this is probably not needed during premerge checks.
+      ## It makes sense to store test results only after testing already code merged into the trunk.
+      ## It does not seem to make sense to upload test results after each push to the branch that has not need merged into the trunk, there will be a lot of useless artifacts on Code Climate.
+      # - name: Upload coverage results to Code Climate
+      #   run: |
+      #     curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > /tmp/cc-test-reporter
+      #     chmod +x /tmp/cc-test-reporter
+      #     /tmp/cc-test-reporter after-build --coverage-input-type lcov --exit-code 0
+      #   env:
+      #     CC_TEST_REPORTER_ID: 3f4c9a9d57ded045e0f9ab5d23e5bbcbf709bb85637bea555f1233e72134b818 # TODO: better store it in the repository secrets. Name the variable: CC_TEST_REPORTER_ID. Then delete this line and uncomment the next one
+      #     # CC_TEST_REPORTER_ID: ${{ secrets.CC_TEST_REPORTER_ID }}