Run tests one by one @ GHA

This workflow just finds all the individual
tests available in core (all the test_ methods
in _test.php file) and runs them one by one,
with a total isolation, because each one is
executed by a different PHPUnit run.

Any test ending with error, will be reported
as part of the output.

Note that we are not using PHPUnit's own
isolation here, just running them one by one.

.github/workflows/onebyone.yml

@@ -0,0 +1,150 @@
+name: One by One Testing
+# Run all the individual unit tests one by one, with
+# fully independent PHPUnit executions. Useful to
+# detect issues with some tests that are using stuff
+# that has been made available by others, but is not
+# available when running individually.
+#
+# Note that we aren't using PHPUnit's own isolation
+# here but completely separated runs, one for each
+# test.
+#
+# The workflow will fail reporting all the tests
+# that have failed (and will pass if no failure is
+# detected, of course).
+#
+# It's only executed via workflow dispatch (automated
+# or manual), not by push/tag. And acceptd configuration
+# of phpunit, specially useful to run it with PHPUnit's
+# own isolation or any other option.
+
+on:
+  push:
+    branches-ignore:
+      - main
+      - master
+      - MOODLE_[0-9]+_STABLE
+    tags-ignore:
+      - v[0-9]+.[0-9]+.[0-9]+*
+  workflow_dispatch:
+    inputs:
+      phpunit_extra_options:
+        description: Additional options to apply to PHPUnit
+        required: false
+        default: ''
+
+env:
+  chunks: 7
+
+jobs:
+  collect:
+    name: Collect individual unit tests
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{steps.individual-tests.outputs.matrix }}
+
+    steps:
+      - name: Checking out code
+        uses: actions/checkout@v4
+
+      - name: Looking for all individual tests
+        id: individual-tests
+        run: |
+          count=0  # Number of individual tests found.
+          while read -r testfile; do # For each test file.
+              while read -r testname; do # For each unit test in a file.
+                  count=$((count + 1))
+                  # Sent it to the correct chunk file.
+                  chunk=$(((($count % $chunks)) + 1))
+                  echo "$testname $testfile" >> ./chunk_$chunk.txt
+              done < <(grep "function test_" "${testfile}" | sed -r "s/^.*function (test_[a-zA-Z0-9_]+).*/\1/")
+          done < <(find . -name "*_test.php")
+          # Generate the matrix to run tests.
+          echo "matrix=$(ls -1 chunk_*.txt | jq -R -s -c 'split("\n")[:-1]')" >> $GITHUB_OUTPUT
+          echo "$count individual tests collected in $chunks files"
+
+      - name: Upload individual tests files
+        uses: actions/upload-artifact@v4
+        with:
+          name: individual_tests
+          path: chunk_*.txt
+          retention-days: 1
+
+  test:
+    name: Run tests
+    needs: collect
+    runs-on: ubuntu-latest
+    services:
+      exttests:
+        image: moodlehq/moodle-exttests
+        ports:
+          - 8080:80
+      redis:
+        image: redis
+        ports:
+          - 6379:6379
+    strategy:
+      fail-fast: false
+      matrix:
+        file: ${{ fromJson(needs.collect.outputs.matrix) }}
+
+    steps:
+      - name: Setting up DB pgsql
+        uses: m4nu56/postgresql-action@v1
+        with:
+          postgresql version: 13
+          postgresql db: test
+          postgresql user: test
+          postgresql password: test
+
+      - name: Setting up PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 8.2
+          ini-values: max_input_vars=5000
+          coverage: none
+
+      - name: Checking out code
+        uses: actions/checkout@v4
+
+      - name: Download individual test files
+        uses: actions/download-artifact@v4
+        with:
+          name: individual_tests # Make all the chunk files available for the next steps.
+
+      - name: Setting up PHPUnit
+        env:
+          dbtype: pgsql
+        run: |
+          echo "pathtophp=$(which php)" >> $GITHUB_ENV
+          cp .github/workflows/config-template.php config.php
+          mkdir ../moodledata
+          sudo locale-gen en_AU.UTF-8
+          php admin/tool/phpunit/cli/init.php --no-composer-self-update
+
+      - name: Run PHPUnit test (one by one)
+        env:
+          dbtype: pgsql
+        run: |
+          status=0
+          count=0
+          while read -r line; do # For each line in the chunk file
+              count=$((count + 1))
+              filter="${line% *}"
+              file="${line#* }"
+              # Run the individual unit test and report problems if needed to.
+              if ! php vendor/bin/phpunit \
+                      --fail-on-empty-test-suite \
+                      --fail-on-warning \
+                      --fail-on-risky \
+                      --filter "$filter" ${{ inputs.phpunit_extra_options }} \
+                      "$file" >/dev/null 2>&1; then
+                  if [ $status -eq 0 ]; then
+                      echo "Problems found, list of PHPUnit commands failing:"
+                  fi
+                  echo "vendor/bin/phpunit --filter '${filter}' ${{ inputs.phpunit_extra_options }} $file"
+                  status=$((status + 1))
+              fi
+          done < ${{ matrix.file }}
+          echo "Finished: $count individual tests executed, $status tests failed"
+          exit $status