Migrate mocha tests from OCaml-style Mt to idiomatic ReScript/JS usage (#7861)

* Biome: ignore lib/js

* Migrate mocha tests from OCaml-style `Mt` to idiomatic ReScript/JS usage

* Update CONTRIBUTING.md

* Add missing describe call

Author: cknitt

CONTRIBUTING.md

@@ -227,14 +227,23 @@ Below we will discuss on how to write, build and run these test files.
 - Inside the file, add a mocha test suite. The mocha bindings are defined in `tests/tests/src/mt.res`. To get you started, here is a simple scaffold for a test suite with multiple test cases:
 
   ```rescript
-  let suites: Mt.pair_suites = list{
-    ("hey", _ => Eq(true, 3 > 2)),
-    ("hi", _ => Neq(2, 3)),
-    ("hello", _ => Approx(3.0, 3.0)),
-    ("throw", _ => ThrowAny(_ => raise(SomeException))),
-  }
-
-  Mt.from_pair_suites(__MODULE__, suites)
+  open Mocha
+  open Test_utils
+
+  describe(__MODULE__, () => {
+    test("hey", () => {
+      ok(__LOC__, 3 > 2)
+    })
+
+    test("hi", () => {
+      eq(__LOC__, 2, 2)
+      eq(__LOC__, 3, 3)
+    })
+
+    test("throw", () => {
+      throws(__LOC__, () => throw(SomeException))
+    })
+  })
   ```
 
 - Build the test files and run the tests: `node scripts/test.js -mocha`.

biome.json

@@ -65,6 +65,7 @@
       "rewatch/**",
       "lib/es6/**",
       "lib/js/**",
+      "lib/bs/**",
       "ninja/**",
       "playground/**",
       "*.bs.js",

tests/tests/src/abstract_type.resi

@@ -4,4 +4,3 @@ type arrow_type = int => int
 
 type poly_type<'a> = 'a
 type poly_abstract_type<'a>
-open Mt

tests/tests/src/and_or_tailcall_test.mjs

@@ -1,6 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Mt from "./mt.mjs";
+import * as Mocha from "mocha";
+import * as Test_utils from "./test_utils.mjs";
 
 function f(b, x, _n) {
   while (true) {
@@ -30,37 +31,13 @@ function or_f(b, x, _n) {
   };
 }
 
-let suites_0 = [
-  "and_tail",
-  param => ({
-    TAG: "Eq",
-    _0: false,
-    _1: f(true, 1, 0)
-  })
-];
-
-let suites_1 = {
-  hd: [
-    "or_tail",
-    param => ({
-      TAG: "Eq",
-      _0: false,
-      _1: or_f(false, 1, 0)
-    })
-  ],
-  tl: /* [] */0
-};
-
-let suites = {
-  hd: suites_0,
-  tl: suites_1
-};
-
-Mt.from_pair_suites("And_or_tailcall_test", suites);
+Mocha.describe("And_or_tailcall_test", () => {
+  Mocha.test("and_tail", () => Test_utils.eq("File \"and_or_tailcall_test.res\", line 21, characters 7-14", false, f(true, 1, 0)));
+  Mocha.test("or_tail", () => Test_utils.eq("File \"and_or_tailcall_test.res\", line 24, characters 7-14", false, or_f(false, 1, 0)));
+});
 
 export {
   f,
   or_f,
-  suites,
 }
 /*  Not a pure module */

tests/tests/src/and_or_tailcall_test.res

@@ -12,13 +12,15 @@ let rec or_f = (b, x, n) =>
     b || or_f(b, x, n + 1)
   }
 
-let suites = {
-  open Mt
-  list{
-    /* becareful inlining will defeat the test purpose here */
-    ("and_tail", _ => Eq(false, f(true, 1, 0))),
-    ("or_tail", _ => Eq(false, or_f(false, 1, 0))),
-  }
-}
+open Mocha
+open Test_utils
 
-Mt.from_pair_suites(__MODULE__, suites)
+describe(__MODULE__, () => {
+  /* becareful inlining will defeat the test purpose here */
+  test("and_tail", () => {
+    eq(__LOC__, false, f(true, 1, 0))
+  })
+  test("or_tail", () => {
+    eq(__LOC__, false, or_f(false, 1, 0))
+  })
+})

tests/tests/src/ari_regress_test.mjs

@@ -1,6 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Mt from "./mt.mjs";
+import * as Mocha from "mocha";
+import * as Test_utils from "./test_utils.mjs";
 
 let g = 7;
 
@@ -22,52 +23,11 @@ function v(__x) {
   return g1(3, 4)(6, __x);
 }
 
-let suites_0 = [
-  "curry",
-  param => ({
-    TAG: "Eq",
-    _0: g,
-    _1: 7
-  })
-];
-
-let suites_1 = {
-  hd: [
-    "curry2",
-    param => ({
-      TAG: "Eq",
-      _0: 14,
-      _1: (v(1), v(1))
-    })
-  ],
-  tl: {
-    hd: [
-      "curry3",
-      param => ({
-        TAG: "Eq",
-        _0: x,
-        _1: 14
-      })
-    ],
-    tl: {
-      hd: [
-        "File \"ari_regress_test.res\", line 35, characters 5-12",
-        param => ({
-          TAG: "Eq",
-          _0: h.contents,
-          _1: 2
-        })
-      ],
-      tl: /* [] */0
-    }
-  }
-};
-
-let suites = {
-  hd: suites_0,
-  tl: suites_1
-};
-
-Mt.from_pair_suites("Ari_regress_test", suites);
+Mocha.describe("Ari_regress_test", () => {
+  Mocha.test("curry", () => Test_utils.eq("File \"ari_regress_test.res\", line 25, characters 7-14", g, 7));
+  Mocha.test("curry2", () => Test_utils.eq("File \"ari_regress_test.res\", line 30, characters 6-13", 14, (v(1), v(1))));
+  Mocha.test("curry3", () => Test_utils.eq("File \"ari_regress_test.res\", line 40, characters 7-14", x, 14));
+  Mocha.test("ref count", () => Test_utils.eq("File \"ari_regress_test.res\", line 44, characters 7-14", h.contents, 2));
+});
 
 /*  Not a pure module */

tests/tests/src/ari_regress_test.res

@@ -1,3 +1,6 @@
+open Mocha
+open Test_utils
+
 let f = x => \"+"(x, ...)
 let g = f(3)(4)
 
@@ -17,23 +20,27 @@ let x = gg(3, 5)(6)
 
 let v = g1(3, 4)(6, _)
 
-let suites = {
-  open Mt
-  list{
-    ("curry", _ => Eq(g, 7)),
-    (
-      "curry2",
-      _ => Eq(
-        14,
-        {
-          ignore(v(1))
-          v(1)
-        },
-      ),
-    ),
-    ("curry3", _ => Eq(x, 14)),
-    (__LOC__, _ => Eq(h.contents, 2)),
-  }
-}
+describe(__MODULE__, () => {
+  test("curry", () => {
+    eq(__LOC__, g, 7)
+  })
+
+  test("curry2", () => {
+    eq(
+      __LOC__,
+      14,
+      {
+        ignore(v(1))
+        v(1)
+      },
+    )
+  })
+
+  test("curry3", () => {
+    eq(__LOC__, x, 14)
+  })
 
-Mt.from_pair_suites(__MODULE__, suites)
+  test("ref count", () => {
+    eq(__LOC__, h.contents, 2)
+  })
+})

tests/tests/src/arity_deopt.mjs

@@ -1,29 +1,7 @@
 // Generated by ReScript, PLEASE EDIT WITH CARE
 
-import * as Mt from "./mt.mjs";
-
-let suites = {
-  contents: /* [] */0
-};
-
-let test_id = {
-  contents: 0
-};
-
-function eq(loc, x, y) {
-  test_id.contents = test_id.contents + 1 | 0;
-  suites.contents = {
-    hd: [
-      loc + (" id " + test_id.contents.toString()),
-      () => ({
-        TAG: "Eq",
-        _0: x,
-        _1: y
-      })
-    ],
-    tl: suites.contents
-  };
-}
+import * as Mocha from "mocha";
+import * as Test_utils from "./test_utils.mjs";
 
 function f0(x, y, z) {
   return (x + y | 0) + z | 0;
@@ -41,20 +19,16 @@ function f3(x) {
   return (y, z) => (x + y | 0) + z | 0;
 }
 
-eq("File \"arity_deopt.res\", line 50, characters 5-12", 6, 6);
-
-eq("File \"arity_deopt.res\", line 51, characters 5-12", 6, 6);
-
-eq("File \"arity_deopt.res\", line 52, characters 5-12", 6, 6);
-
-eq("File \"arity_deopt.res\", line 53, characters 5-12", 6, 6);
-
-Mt.from_pair_suites("Arity_deopt", suites.contents);
+Mocha.describe("Arity_deopt", () => {
+  Mocha.test("arity_deopt_tests", () => {
+    Test_utils.eq("File \"arity_deopt.res\", line 43, characters 7-14", 6, 6);
+    Test_utils.eq("File \"arity_deopt.res\", line 44, characters 7-14", 6, 6);
+    Test_utils.eq("File \"arity_deopt.res\", line 45, characters 7-14", 6, 6);
+    Test_utils.eq("File \"arity_deopt.res\", line 46, characters 7-14", 6, 6);
+  });
+});
 
 export {
-  suites,
-  test_id,
-  eq,
   f0,
   f1,
   f2,

tests/tests/src/arity_deopt.res

@@ -1,13 +1,5 @@
-let suites: ref<Mt.pair_suites> = ref(list{})
-let test_id = ref(0)
-let eq = (loc, x, y) => {
-  incr(test_id)
-  suites :=
-    list{
-      (loc ++ (" id " ++ Js.Int.toString(test_id.contents)), _ => Mt.Eq(x, y)),
-      ...suites.contents,
-    }
-}
+open Mocha
+open Test_utils
 
 /* let f = fun x y */
 
@@ -46,10 +38,11 @@ let f3 = x => {
    (Ml_app) will not hold any more.
    So the best is never shrink functons which could change arity
 */
-let () = {
-  eq(__LOC__, 6, ...)(f0(1, 2, 3))
-  eq(__LOC__, 6, ...)(f1(1)(2, 3))
-  eq(__LOC__, 6, ...)(f2(1, 2)(3))
-  eq(__LOC__, 6, ...)(f3(1)(2, 3))
-}
-let () = Mt.from_pair_suites(__MODULE__, suites.contents)
+describe(__MODULE__, () => {
+  test("arity_deopt_tests", () => {
+    eq(__LOC__, 6, f0(1, 2, 3))
+    eq(__LOC__, 6, f1(1)(2, 3))
+    eq(__LOC__, 6, f2(1, 2)(3))
+    eq(__LOC__, 6, f3(1)(2, 3))
+  })
+})