ci: test against xsh's full shell matrix (bash 3.2/4.4/5.x + zsh)

Mirror alexzhangs/xsh's CI matrix so the library is exercised on every shell
the framework supports: bash 3.2 (macOS), 4.4 (rockylinux:8 container),
5.x (Linux + Homebrew macOS), and zsh 5.x (macOS + Linux). Previously only
bash 3.2/5.x + zsh were covered.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: alexzhangs

.github/workflows/ci-unittest.yml

@@ -1,50 +1,75 @@
 name: ci-unittest
 
-on: [push, pull_request]
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
 
 jobs:
   test:
     runs-on: ${{ matrix.os }}
-    name: ${{ matrix.os }} / ${{ matrix.shell }}
+    container: ${{ matrix.container }}
+    name: ${{ matrix.label }}
+    defaults:
+      run:
+        shell: bash
+    # Mirror alexzhangs/xsh's shell matrix: bash 3.2 / 4.4 / 5.x + zsh 5.x.
+    # Utilities run under zsh's ksh emulation (provided by xsh >= 0.7.0).
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest]
-        # bash is the historical target; zsh is the macOS default login shell.
-        # Utilities run under zsh's ksh emulation (provided by xsh).
-        shell: [bash, zsh]
+        include:
+          - { os: ubuntu-latest, container: '',           shell_path: /bin/bash,    label: bash-5.x-linux }
+          - { os: macos-latest,  container: '',           shell_path: /bin/bash,    label: bash-3.2-macos }
+          - { os: macos-latest,  container: '',           shell_path: brew,         label: bash-5.x-macos }
+          - { os: ubuntu-latest, container: rockylinux:8, shell_path: /bin/bash,    label: bash-4.4-linux }
+          - { os: macos-latest,  container: '',           shell_path: /bin/zsh,     label: zsh-5.x-macos }
+          - { os: ubuntu-latest, container: '',           shell_path: /usr/bin/zsh, label: zsh-5.x-linux }
 
     steps:
-    - uses: actions/checkout@v4
-
-    - name: Install zsh (Linux)
-      if: matrix.shell == 'zsh' && runner.os == 'Linux'
-      run: sudo apt-get update && sudo apt-get install -y zsh
-
-    - name: Install xsh
-      run: |
-        git clone --depth=50 https://github.com/alexzhangs/xsh.git xsh-source
-        bash xsh-source/install.sh
-
-    - name: Load deps
-      run: |
-        # shellcheck disable=SC1090
-        source ~/.xshrc
-        xsh load xsh-lib/core
-        # Load this lib at the branch under test. xsh load does a full clone
-        # from origin and checks out the branch, so the workflow exercises the
-        # commit that triggered it. Fork PRs fall back to the default branch
-        # (the source branch isn't on the main repo).
-        BRANCH="${GITHUB_HEAD_REF:-${GITHUB_REF_NAME}}"
-        xsh load -b "$BRANCH" xsh-lib/git || xsh load xsh-lib/git
-
-    - name: Run tests (${{ matrix.shell }})
-      run: |
-        # shellcheck disable=SC1090
-        source ~/.xshrc
-        xsh version
-        xsh list
-        # test.sh self-sources ~/.xshrc, so running it under the matrix shell
-        # makes the utilities execute under that shell (bash, or zsh's ksh
-        # emulation).
-        ${{ matrix.shell }} test.sh
+      - name: Pre-install git (rockylinux container)
+        if: matrix.container != ''
+        run: dnf install -y git
+
+      - name: Install dependencies (rockylinux container)
+        if: matrix.container != ''
+        run: |
+          dnf install -y --allowerasing coreutils
+          dnf install -y gawk sed file findutils diffutils procps-ng which tar gzip python3
+          command -v python >/dev/null 2>&1 || ln -sf "$(command -v python3)" /usr/local/bin/python
+          git config --global --add safe.directory '*'
+
+      - name: Install zsh (Linux)
+        if: matrix.container == '' && runner.os == 'Linux' && contains(matrix.shell_path, 'zsh')
+        run: sudo apt-get update && sudo apt-get install -y zsh
+
+      - name: Install Homebrew bash (macOS bash 5.x)
+        if: matrix.shell_path == 'brew'
+        run: |
+          brew install bash
+          echo "SHELL_PATH=$(brew --prefix)/bin/bash" >> "$GITHUB_ENV"
+
+      - name: Set shell path
+        if: matrix.shell_path != 'brew'
+        run: echo "SHELL_PATH=${{ matrix.shell_path }}" >> "$GITHUB_ENV"
+
+      - name: Install xsh
+        run: |
+          git clone --depth=50 --branch=master https://github.com/alexzhangs/xsh.git /tmp/xsh
+          bash /tmp/xsh/install.sh
+
+      - name: Load dependency library xsh-lib/core
+        run: |
+          source ~/.xshrc
+          xsh load xsh-lib/core
+
+      - name: Load library from current branch
+        run: |
+          source ~/.xshrc
+          # Fork PRs fall back to the default branch (the source branch isn't on
+          # the main repo).
+          xsh load -b "${{ github.head_ref || github.ref_name }}" xsh-lib/git || xsh load xsh-lib/git
+
+      - name: Run tests (${{ matrix.label }})
+        run: "$SHELL_PATH" ~/.xsh/repo/xsh-lib/git/test.sh