Run internal tests in Cygwin (#1592)

.github/workflows/testing.yml

@@ -320,3 +320,40 @@ jobs:
         shell: bash
         run: |
           test/run-tests.sh
+
+  cygwin:
+    strategy:
+      matrix:
+        bits: [32, 64]
+        include:
+          - bits: 32
+            arch: x86
+          - bits: 64
+            arch: x86_64
+      fail-fast: false
+    runs-on: windows-2019
+    timeout-minutes: 30
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4
+      - name: Setup Cygwin
+        uses: cygwin/cygwin-install-action@v4
+        with:
+          platform: ${{ matrix.arch }}
+          packages: >-
+            bison
+            gcc-g++
+            git
+            libpng-devel
+            make
+            pkg-config
+      - name: Build & install using Make
+        shell: C:\cygwin\bin\env.exe CYGWIN_NOWINPATH=1 CHERE_INVOKING=1 C:\cygwin\bin\bash.exe -o igncr '{0}'
+        run: | # Cygwin does not support `make develop` sanitizers ASan or UBSan
+          make -kj Q=
+          make install -j Q=
+      - name: Run tests
+        shell: C:\cygwin\bin\env.exe CYGWIN_NOWINPATH=1 CHERE_INVOKING=1 C:\cygwin\bin\bash.exe -o igncr '{0}'
+        run: | # Allow asm/test.sh to run `git describe` for the version test
+          git config --global --add safe.directory '*'
+          test/run-tests.sh --only-internal