feat: Introduce bashunit test suite

This introduces the bashunit test suite as requested by @jrfnl. I opted to include the binary in the repository to make local testing easier & to lock the dependency on the project side instead of relying on external scripts.

This tests both a simple happy and a simple unhappy flow, as well as a test case for PHPCSStandards#1112.

Author: NanoSector

.github/workflows/bashunit-tests.yml

@@ -0,0 +1,33 @@
+# example: .github/workflows/bashunit-tests.yml
+name: BashUnit Tests
+
+on:
+  # Run on all pushes and on all pull requests.
+  # Prevent the build from running when there are only irrelevant changes.
+  push:
+    paths-ignore:
+      - '**.md'
+      - '**.xml'
+  pull_request:
+  # Allow manually triggering the workflow.
+  workflow_dispatch:
+
+# Cancels all previous workflow runs for the same branch that have not yet completed.
+concurrency:
+  # The concurrency group contains the workflow name and the branch name.
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  bashunit:
+    name: "Run tests"
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: "Install patch"
+        run: "sudo apt-get install -y patch"
+
+      - name: "Run bashunit tests"
+        run: "./scripts/bashunit -p tests/EndToEnd"