Extract PIT results comment step as reusable action

Author: emlun

.github/actions/pit-results-comment/action.yml

@@ -0,0 +1,56 @@
+name: Post PIT mutation test results comment
+author: Emil Lundberg <[email protected]>
+description: |
+  Parses a [PIT][pitest] report file, compares it to a previous report,
+  and posts a summary as a commit comment to the commit that triggered the workflow.
+
+  [pitest]: https://pitest.org/
+
+inputs:
+  mutations-file:
+    default: build/reports/pitest/mutations.xml
+    description: Path to the PIT report XML file.
+
+  prev-commit:
+    default: ''
+    description: |
+      The full commit SHA of the previous run of this action.
+      If set, the comment will include a link to the previous commit.
+
+  prev-mutations-file:
+    required: true
+    description: Path to the PIT report XML file from the previous run of this action.
+
+  token:
+    default: ${{ github.token }}
+    description: GITHUB_TOKEN or a PAT with permission to write commit comments.
+
+runs:
+  using: "composite"
+
+  steps:
+    - name: Install yq (and xq)
+      shell: bash
+      run: pip install yq
+
+    - name: Post results comment
+      shell: bash
+      run: |
+        RESULTS_COMMENT_FILE=$(mktemp)
+        NEW_STATS_FILE=$(mktemp)
+        PREV_STATS_FILE=$(mktemp)
+
+        ./.github/actions/pit-results-comment/compute-stats.sh "${{ inputs.mutations-file }}" > "${NEW_STATS_FILE}"
+
+        if [[ -f "${{ inputs.prev-mutations-file }}" ]]; then
+          ./.github/actions/pit-results-comment/compute-stats.sh "${{ inputs.prev-mutations-file }}" > "${PREV_STATS_FILE}"
+        else
+          echo 'Previous mutations file not found, using current as placeholder.'
+          cp "${NEW_STATS_FILE}" "${PREV_STATS_FILE}"
+        fi
+
+        ./.github/actions/pit-results-comment/stats-to-comment.sh "${PREV_STATS_FILE}" "${NEW_STATS_FILE}" "${{ inputs.prev-commit }}" > "${RESULTS_COMMENT_FILE}"
+
+        curl -X POST \
+           -H "Authorization: Bearer ${{ inputs.token }}" \
+           ${{ github.api_url }}/repos/${{ github.repository }}/commits/${{ github.sha }}/comments -d @"${RESULTS_COMMENT_FILE}"

.github/workflows/coverage/compute-stats.sh renamed to .github/actions/pit-results-comment/compute-stats.sh

@@ -70,25 +70,16 @@ jobs:
         ref: gh-pages
         clean: false
 
-    - name: Post mutation test results as commit comment
+    - name: Prepare metadata for pit-results-comment action
       run: |
-        git checkout "${GITHUB_SHA}" -- .github/workflows/coverage
-
-        ./.github/workflows/coverage/compute-stats.sh build/reports/pitest/mutations.xml > new-stats.json
-
-        if [[ -f prev-mutations.xml ]]; then
-          ./.github/workflows/coverage/compute-stats.sh prev-mutations.xml > prev-stats.json
-        else
-          cp new-stats.json prev-stats.json
-        fi
-
-        touch prev-commit.txt
+        git checkout "${GITHUB_SHA}" -- .github/workflows/coverage .github/actions
+        echo PREV_COMMIT=$(cat prev-commit.txt) >> "${GITHUB_ENV}"
 
-        ./.github/workflows/coverage/stats-to-comment.sh prev-stats.json new-stats.json $(cat prev-commit.txt) > build/results-comment.json
-
-        curl -X POST \
-           -H "Authorization: Bearer ${{ secrets.GITHUB_TOKEN }}" \
-           ${GITHUB_API_URL}/repos/${GITHUB_REPOSITORY}/commits/${GITHUB_SHA}/comments -d @build/results-comment.json
+    - name: Post mutation test results as commit comment
+      uses: ./.github/actions/pit-results-comment
+      with:
+        prev-commit: ${{ env.PREV_COMMIT }}
+        prev-mutations-file: prev-mutations.xml
 
     - name: Push to GitHub Pages
       run: |