Update to be compatible with ESM

CHANGES.md

@@ -1,3 +1,9 @@
+## Unreleased
+
+- Migrate bindings to work with ESM. NOTE: CommonJS support is removed from this
+  version, if you need to use CommonJS, please check previous version 0.1.1
+  ([#12](https://github.com/melange-community/melange-jest/pull/12))
+
 ## 0.1.1 (2024-02-03)
 
 - compatibility with melange v3

README.md

@@ -83,6 +83,12 @@ If you need `jest-dom`, add `melange-jest.jest-dom` to the `libraries` in your `
 ; ...
 ```
 
+## ECMAScript Modules (aka "ESM")
+
+These bindings are only compatible with ECMAScript (ESM) modules, and not CommonJS. If you need a version that is compatible with CommonJS, please check v0.1.1.
+
+You can refer to the [official Jest documentation](https://jestjs.io/docs/ecmascript-modules) to see how to use Jest with ESM. Note that it will require using Node with version 18 (at least), and use `node --experimental-vm-modules node_modules/jest/bin/jest.js` to run the tests.
+
 ## Usage
 
 Put tests in a `__tests__` directory and use the suffix `*test.ml`/`*test.re` (Make sure to use valid module names. e.g. `<name>_test.re` is valid while `<name>.test.re` is not). When compiled they will be put in a `__tests__` directory under `lib`, with a `*test.js` suffix, ready to be picked up when you run `jest`. If you're not already familiar with [Jest](https://github.com/facebook/jest), see [the Jest documentation](https://facebook.github.io/jest/).
@@ -115,16 +121,16 @@ In a `dune` file:
 
 ### 2. Error `Cannot use import statement outside a module`
 
-If you encounter the error `SyntaxError: Cannot use import statement outside a module`, it may be that you are trying to run Jest tests with `es6` files generated by Melange.
+If you encounter the error `SyntaxError: Cannot use import statement outside a module`, you might be missing the `mjs` extension on the generated files.
 
-As Melange allows to have generate both `es6` and `commonjs` outputs in the same project, to solve this issue you can add a `melange.emit` stanza that only generates `commonjs` files, for testing purposes.
+As Melange allows to have generate both `es6` and `commonjs` outputs in the same project, to solve this issue you can add a `melange.emit` stanza that only generates `es6` files with `mjs` extension, for testing purposes.
 
 In a `dune` file:
 
   ```clojure
   (melange.emit
     (target test)
-    (module_systems commonjs)
+    (module_systems (es6 mjs))
     ...
   )
   ```

dune

@@ -9,4 +9,4 @@
  (deps
   (alias_rec test))
  (action
-  (run npx jest)))
+  (run node --experimental-vm-modules %{project_root}/../../node_modules/jest/bin/jest.js)))

jest-dom/__tests__/dune

@@ -2,5 +2,6 @@
  (target test)
  (alias test)
  (libraries jest jestDom melange-webapi)
+ (module_systems (es6 mjs))
  (preprocess
   (pps melange.ppx)))

jest-dom/jestDom.ml

@@ -1,4 +1,4 @@
-let _ = [%mel.raw {|require('@testing-library/jest-dom')|}]
+[%%mel.raw {|import '@testing-library/jest-dom'|}]
 
 type expect
 type t = Dom.element

jest.config.js

@@ -1,5 +1,5 @@
 module.exports = {
     rootDir: "./_build/default/",
-    testMatch: ["**/*_test.js"],
+    testMatch: ["**/*_test.mjs"]
 };
 

jest/__tests__/dune

@@ -2,5 +2,6 @@
  (target test)
  (alias test)
  (libraries jest)
+ (module_systems (es6 mjs))
  (preprocess
   (pps melange.ppx)))

jest/__tests__/globals_test.ml

@@ -369,4 +369,4 @@ let () =
 
   describe "Todo" (fun () ->
     Todo.test "Todo.test";
-  )
+  )

jest/__tests__/jest_test.ml

@@ -3,6 +3,8 @@ open Expect
 open! Expect.Operators
 
 external setTimeout : (unit -> unit) -> int -> unit = "setTimeout"
+type timers
+external timers : timers = "timers" [@@mel.module]
 external setImmediate : (unit -> unit) -> unit = "setImmediate"
 external nextTick : (unit -> unit) -> unit = "process.nextTick"
 
@@ -11,85 +13,85 @@ let () =
 describe "Fake Timers" (fun () ->
   test "runAllTimers" (fun () ->
     let flag = ref false in
-    Jest.useFakeTimers ();
+    Jest.useFakeTimers () Jest.(jest globals);
     setTimeout (fun () -> flag := true) 0;
     let before = !flag in
-    Jest.runAllTimers ();
+    Jest.runAllTimers () Jest.(jest globals);
 
     expect (before, !flag) = (false, true)
   );
 
   test "runAllTicks" (fun () ->
     let flag = ref false in
-    Jest.useFakeTimers ();
+    Jest.useFakeTimers () Jest.(jest globals);
     nextTick (fun () -> flag := true);
     let before = !flag in
-    Jest.runAllTicks ();
+    Jest.runAllTicks () Jest.(jest globals);
 
     expect (before, !flag) = (false, true)
   );
 
   test "runAllImmediates" (fun () ->
     let flag = ref false in
-    Jest.useFakeTimers ~config:{legacyFakeTimers=true} ();
+    Jest.useFakeTimers ~config:{legacyFakeTimers=true} () Jest.(jest globals);
     setImmediate (fun () -> flag := true);
     let before = !flag in
-    Jest.runAllImmediates ();
+    Jest.runAllImmediates () Jest.(jest globals);
 
     expect (before, !flag) = (false, true)
-  );
+  ); 
 
   test "runTimersToTime" (fun () ->
     let flag = ref false in
-    Jest.useFakeTimers ();
+    Jest.useFakeTimers () Jest.(jest globals);
     setTimeout (fun () -> flag := true) 1500;
     let before = !flag in
-    Jest.advanceTimersByTime 1000;
+    Jest.advanceTimersByTime 1000 Jest.(jest globals);
     let inbetween = !flag in
-    Jest.advanceTimersByTime 1000;
+    Jest.advanceTimersByTime 1000 Jest.(jest globals);
 
     expect (before, inbetween, !flag) = (false, false, true)
   );
 
   test "advanceTimersByTime" (fun () ->
     let flag = ref false in
-    Jest.useFakeTimers ();
+    Jest.useFakeTimers () Jest.(jest globals);
     setTimeout(fun () -> flag := true) 1500;
     let before = !flag in
-    Jest.advanceTimersByTime 1000;
+    Jest.advanceTimersByTime 1000 Jest.(jest globals);
     let inbetween = !flag in
-    Jest.advanceTimersByTime 1000;
+    Jest.advanceTimersByTime 1000 Jest.(jest globals);
 
     expect (before, inbetween, !flag) = (false, false, true)
   );
 
   test "runOnlyPendingTimers" (fun () ->
     let count = ref 0 in
-    Jest.useFakeTimers ();
+    Jest.useFakeTimers () Jest.(jest globals);
     let rec recursiveTimeout () = count := !count + 1; setTimeout recursiveTimeout 1500 in
     recursiveTimeout ();
     let before = !count in
-    Jest.runOnlyPendingTimers ();
+    Jest.runOnlyPendingTimers () Jest.(jest globals);
     let inbetween = !count in
-    Jest.runOnlyPendingTimers ();
+    Jest.runOnlyPendingTimers () Jest.(jest globals);
 
     expect (before, inbetween, !count) = (1, 2, 3)
   );
 
   test "clearAllTimers" (fun () ->
     let flag = ref false in
-    Jest.useFakeTimers ();
+    Jest.useFakeTimers () Jest.(jest globals);
     setImmediate (fun () -> flag := true);
     let before = !flag in
-    Jest.clearAllTimers ();
-    Jest.runAllTimers ();
+    Jest.clearAllTimers () Jest.(jest globals);
+    Jest.runAllTimers () Jest.(jest globals);
 
     expect (before, !flag) = (false, false)
   );
 
   testAsync "clearAllTimers" (fun finish ->
-    Jest.useFakeTimers ();
-    Jest.useRealTimers ();
+    Jest.useFakeTimers () Jest.(jest globals);
+    Jest.useRealTimers () Jest.(jest globals);
     nextTick (fun () -> finish pass);
   );
 );