test C program to check we can find the ocaml headers (#15)

Summary: Pull Request resolved: #15

Test Plan: https://github.com/shayne-fletcher/ocaml-scripts/actions/runs/8104512093

Reviewed By: bigfootjon

Differential Revision: D54416893

Pulled By: shayne-fletcher

fbshipit-source-id: f64e37bc0c554afed620e764c07cdeb0b876ef0a

.github/workflows/run-tests.yml

@@ -13,18 +13,22 @@ jobs:
         os: [ubuntu, macos]
     steps:
       - uses: actions/checkout@v4
+        with:
+          submodules: 'true'
+      - uses: facebook/install-dotslash@latest
       - run: sudo apt-get update && sudo apt-get install opam
         if: matrix.os == 'ubuntu'
       - run: brew install opam
         if: matrix.os == 'macos'
       - run: |-
-          opam init --compiler=5.1.1 --disable-sandboxing -y
-          opam install ocamlfind
+          opam init --color=always --compiler=5.1.1 --disable-sandboxing -y
+          opam install --color=always ocamlfind
           opam env | sed -e "s/ export .*//g" -e "s/'//g" -e "s/\;//g" >> $GITHUB_ENV
       - run: |-
           mkdir -p third-party/ocaml
-          cd third-party/ocaml
-          ln -s "$OPAM_SWITCH_PREFIX" opam
-      - run: |-
+          (cd third-party/ocaml && ln -s "$OPAM_SWITCH_PREFIX" opam)
           python3 dromedary.py -s "$(basename $OPAM_SWITCH_PREFIX)" -o third-party/ocaml/BUCK.test
           cat third-party/ocaml/BUCK.test
+      - run: |-
+          PATH=$(pwd):$PATH; export PATH
+          buck2 run root//test:version -v 2

test/BUCK.test

@@ -1,8 +1,21 @@
+# Example commands to generate 'third-party/ocaml/BUCK.test'.
+# ```
+#   mkdir -p third-party/ocaml
+#   python3 ~/project/ocaml-scripts/dromedary.py -s "$(basename $OPAM_SWITCH_PREFIX)" -o ~/project/ocaml-scripts/third-party/ocaml/BUCK.test
+# ```
+
 _SUPPORTED = not host_info().os.is_windows
 
+# buildifier: disable=no-effect
+cxx_binary(
+    name = "version",
+    srcs = ["version.c"],
+    deps = ["root//third-party/ocaml:ocaml-dev"],
+) if _SUPPORTED else None
+
 # buildifier: disable=no-effect
 ocaml_binary(
-    name = "test-unix",
-    srcs = ["test_unix.ml"],
+    name = "unix",
+    srcs = ["unix.ml"],
     deps = ["root//third-party/ocaml:unix"],
 ) if _SUPPORTED else None

test/version.c

@@ -0,0 +1,13 @@
+#include <stdio.h>
+
+#include <caml/version.h>
+
+char const* ocaml_version() {
+  return OCAML_VERSION_STRING;
+}
+
+int main() {
+  printf("The OCaml toolchain, version %s\n", ocaml_version());
+
+  return 0;
+}