add test for Git 2.15

Author: linkdata

.github/workflows/self-test.yml

@@ -130,3 +130,75 @@ jobs:
         run: |
           set -euo pipefail
           test "${{ steps.detached_tag.outcome }}" = "failure"
+
+  git-2-15-compat:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out action source
+        uses: actions/checkout@v4
+        with:
+          path: action-src
+
+      - name: Install Git 2.15.0
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          sudo apt-get update
+          sudo apt-get install -y \
+            build-essential \
+            gettext \
+            libcurl4-openssl-dev \
+            libexpat1-dev \
+            libssl-dev \
+            zlib1g-dev
+
+          curl -fsSL https://www.kernel.org/pub/software/scm/git/git-2.15.0.tar.xz -o git-2.15.0.tar.xz
+          tar -xf git-2.15.0.tar.xz
+
+          pushd git-2.15.0 >/dev/null
+            make prefix="${RUNNER_TEMP}/git-2.15.0" -j"$(nproc)" all
+            make prefix="${RUNNER_TEMP}/git-2.15.0" install
+          popd >/dev/null
+
+          echo "${RUNNER_TEMP}/git-2.15.0/bin" >> "$GITHUB_PATH"
+
+      - name: Verify Git version
+        shell: bash
+        run: |
+          set -euo pipefail
+          test "$(git --version | awk '{print $3}')" = "2.15.0"
+
+      - name: Prepare local fixture repository
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          git init --bare remote.git
+          git init .
+          git config user.email "ci@example.com"
+          git config user.name "CI"
+          git checkout -b main
+
+          echo "fixture report" > report.html
+          git add report.html
+          git commit -m "init fixture"
+
+          git remote add origin "remote.git"
+          git push -u origin main
+
+      - name: Run action with explicit branch
+        uses: ./action-src
+        with:
+          coverage: "75%"
+          branch: main
+          report: report.html
+
+      - name: Verify Git 2.15.0 run
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          files="$(git --git-dir=remote.git ls-tree --name-only -r coverage)"
+          echo "$files" | grep -Fx "main/badge.svg"
+          echo "$files" | grep -Fx "main/report.html"

README.md

@@ -10,12 +10,7 @@ This action has no dependencies except for `git`, a `bash` shell and common *nix
 It supports Linux/macOS runners and Windows runners with Bash tooling (Git Bash/WSL-enabled images such as
 `windows-2025`).
 
-Git features required by this action:
-- `git worktree add --detach` (documented in Git 2.5.6)
-- `git branch --format` (present in Git 2.13.7, absent in 2.12.5)
-- `git rev-parse --is-shallow-repository` (added in Git 2.15 release notes)
-
-Therefore, use **Git 2.15.0 or newer**.
+Requires **Git 2.15.0 or newer**.
 
 ## Usage
 
@@ -39,6 +34,7 @@ If you submitted a detailed HTML report of the coverage to the action, replace t
 - `report` (optional): Path to an HTML report file to publish as `report.html`.
 - `branch` (optional): Source branch override. Recommended for tag-triggered workflows where multiple branches may contain the same tag commit.
   Also recommended for very large or restricted repos to avoid scanning all remote branches during tag-triggered branch resolution.
+  A Git-valid branch name may still be an invalid Windows path component (for example names containing `<`, `>`, `|`, or `"`), which can fail on Windows runners because this action writes files under `<branch>/...`.
 
 ## Examples