Add support for checking out non-existent branches in JUnit reports workflow

Author: Donnerbart

.github/workflows/integration-test.yml

@@ -162,11 +162,49 @@ jobs:
           name: junit-xml-reports-sha
           failOnError: false
 
+  checkout-junit-reports-nonexistent-branch-test:
+    name: Checkout JUnit reports with non-existent branch
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout split-tests-java-action
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
+
+      - name: Checkout JUnit reports (non-existent branch)
+        uses: ./checkout-junit-reports
+        with:
+          split-index: 0
+          git-branch: junit-reports-it-${{ github.sha }}-nonexistent
+          path: junit-reports-nonexistent-branch
+          upload-artifact: false
+
+      - name: Assert non-existent branch checkout
+        run: |
+          echo "Verifying that checkout with non-existent branch succeeded"
+          if [ ! -d "junit-reports-nonexistent-branch" ]; then
+            echo "Error: Directory junit-reports-nonexistent-branch was not created!"
+            exit 1
+          fi
+          cd junit-reports-nonexistent-branch
+          # Should be on the default branch, verify we have the action files
+          if [ ! -f "action.yml" ]; then
+            echo "Error: action.yml not found - checkout didn't work properly!"
+            ls -la
+            exit 1
+          fi
+          # Verify we're not on the non-existent branch
+          CURRENT_BRANCH=$(git branch --show-current)
+          if [ "$CURRENT_BRANCH" == "junit-reports-it-${{ github.sha }}-nonexistent" ]; then
+            echo "Error: Should not be on the non-existent branch!"
+            exit 1
+          fi
+          echo "Successfully verified checkout with non-existent branch stays on default branch"
+
   generate-split-index-json:
     name: Generate split indexes
     runs-on: ubuntu-latest
     needs:
-      checkout-junit-reports-test
+      - checkout-junit-reports-test
+      - checkout-junit-reports-nonexistent-branch-test
     outputs:
       json: ${{ steps.generate.outputs.split-index-json }}
     steps:

checkout-junit-reports/action.yml

@@ -49,40 +49,47 @@ runs:
         name: ${{ inputs.artifact-name }}
         path: ${{ inputs.artifact-path }}
 
+    - name: Checkout repository
+      uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
+      with:
+        path: ${{ inputs.path }}
+
     - name: Check JUnit reports SHA
       id: junit-reports-sha
       shell: bash
+      working-directory: ${{ inputs.path }}
       run: |
         echo "Checking JUnit reports SHA"
         UPLOAD_SHA_ARTIFACT=${{ inputs.upload-artifact }}
         CHECKOUT_REF=${{ inputs.git-branch }}
-        if [ -d ${{ inputs.artifact-path }} ]; then
-          cd ${{ inputs.artifact-path }}
-          if [ -f junit-reports-sha.txt ]; then
+        if [ -f ../${{ inputs.artifact-path }}/junit-reports-sha.txt ]; then
+          SAVED_SHA=$(cat ../${{ inputs.artifact-path }}/junit-reports-sha.txt)
+          echo "Checking out saved SHA '$SAVED_SHA' for repeatable test distribution"
+          git fetch --quiet
+          git checkout $SAVED_SHA
+          UPLOAD_SHA_ARTIFACT=false
+        else
+          # no SHA artifact exists, handle branch checkout and potentially create new SHA artifact
+          if git ls-remote --exit-code --heads origin $CHECKOUT_REF; then
+            echo "Switching to existing branch: $CHECKOUT_REF"
+            git fetch --quiet
+            git switch $CHECKOUT_REF
+          else
+            echo "Branch $CHECKOUT_REF does not exist, staying on default branch"
             UPLOAD_SHA_ARTIFACT=false
-            CHECKOUT_REF=$(cat junit-reports-sha.txt)
           fi
-        else
-          mkdir ${{ inputs.artifact-path }} || true
         fi
         if [ "$UPLOAD_SHA_ARTIFACT" == "true" ]; then
-          echo "Checking out JUnit reports from branch $CHECKOUT_REF"
+          echo "Will upload JUnit reports SHA for branch $CHECKOUT_REF"
         else
-          echo "Checking out JUnit reports from previously used SHA $CHECKOUT_REF"
+          echo "Will not upload JUnit reports SHA"
         fi
         # we can only upload the artifact once, so only do this on the first split
         if [ "${{ inputs.split-index }}" != "0" ]; then
           echo "Skipping upload of JUnit reports SHA on this index"
           UPLOAD_SHA_ARTIFACT=false
         fi
         echo "upload-artifact=${UPLOAD_SHA_ARTIFACT}" >> "$GITHUB_OUTPUT"
-        echo "ref=${CHECKOUT_REF}" >> "$GITHUB_OUTPUT"
-
-    - name: Checkout repository
-      uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
-      with:
-        path: ${{ inputs.path }}
-        ref: ${{ steps.junit-reports-sha.outputs.ref }}
 
     - name: Save JUnit reports SHA
       if: ${{ steps.junit-reports-sha.outputs.upload-artifact == 'true' }}
@@ -91,6 +98,7 @@ runs:
       run: |
         SHA=$(git rev-parse HEAD)
         echo "Saving JUnit reports SHA $SHA"
+        mkdir -p ../${{ inputs.artifact-path }}
         cd ../${{ inputs.artifact-path }}
         echo -n "$SHA" > junit-reports-sha.txt