Add GitHub Actions workflow

.github/workflows/workflow.yml

@@ -0,0 +1,65 @@
+name: Main workflow
+
+on:
+  - pull_request
+  - push
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - macos-latest
+          - ubuntu-latest
+        ocaml-version:
+          - 4.08.x
+          - 4.09.x
+          - 4.10.x
+          - 4.11.x
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Use OCaml ${{ matrix.ocaml-version }}
+        uses: actions-ml/setup-ocaml@master
+        with:
+          ocaml-version: ${{ matrix.ocaml-version }}
+          dune-cache: true
+          opam-depext: false
+          opam-pin: false
+
+      - run: |
+          opam pin add cohttp-async.dev . --no-action
+          opam pin add cohttp-lwt-jsoo.dev . --no-action
+          opam pin add cohttp-lwt-unix-nossl.dev . --no-action
+          opam pin add cohttp-lwt-unix-ssl.dev . --no-action
+          opam pin add cohttp-lwt-unix.dev . --no-action
+          opam pin add cohttp-lwt.dev . --no-action
+          opam pin add cohttp-mirage.dev . --no-action
+          opam pin add cohttp-top.dev . --no-action
+          opam pin add cohttp.dev . --no-action
+
+      - run: |
+          opam depext --yes \
+          cohttp \
+          cohttp-async \
+          cohttp-lwt \
+          cohttp-lwt-jsoo \
+          cohttp-lwt-unix \
+          cohttp-lwt-unix-nossl \
+          cohttp-lwt-unix-ssl \
+          cohttp-mirage \
+          cohttp-top \
+
+      - run: echo "PKG_CONFIG_PATH=$(brew --prefix openssl)/lib/pkgconfig" >>"$GITHUB_ENV"
+        if: ${{ matrix.os == 'macos-latest' }}
+
+      - run: opam install . --deps-only --with-doc --with-test --yes
+
+      - run: opam exec -- make build
+
+      - run: opam exec -- make test