Add codepoint tests

Author: GearsDatapacks

test/language/test/ffi.gleam

@@ -23,3 +23,7 @@ pub fn halt(a: Int) -> Nil
 @external(erlang, "ffi_erlang", "to_dynamic")
 @external(javascript, "./ffi_javascript.mjs", "toDynamic")
 pub fn to_dynamic(a: x) -> Dynamic
+
+@external(erlang, "ffi_erlang", "to_codepoint")
+@external(javascript, "./ffi_javascript.mjs", "toCodepoint")
+pub fn utf_codepoint(a: Int) -> UtfCodepoint

test/language/test/ffi_erlang.erl

@@ -1,14 +1,14 @@
 -module(ffi_erlang).
 
 -export([
-    to_string/1, append/2, print/1, file_exists/1, halt/1, to_dynamic/1
+    to_string/1, append/2, print/1, file_exists/1, halt/1, to_dynamic/1, to_codepoint/1
 ]).
 
 append(A, B) ->
     <<A/binary, B/binary>>.
 
 print(S) ->
-    io:format("~s", [S]), 
+    io:format("~s", [S]),
     nil.
 
 to_string(Term) ->
@@ -23,3 +23,5 @@ halt(Code) ->
 
 to_dynamic(X) ->
     X.
+
+to_codepoint(X) -> X.

test/language/test/ffi_javascript.mjs

@@ -1,3 +1,5 @@
+import { UtfCodepoint } from "./gleam.mjs";
+
 let fs;
 
 if (!globalThis.Deno) {
@@ -50,3 +52,7 @@ export function halt(code) {
 export function toDynamic(a) {
   return a;
 }
+
+export function toCodepoint(x) {
+  return new UtfCodepoint(x);
+}

test/language/test/language_test.gleam

@@ -1698,6 +1698,22 @@ fn non_utf8_string_bit_array_tests() -> List(Test) {
           message
         })
       }),
+    "UTF-16 codepoint"
+      |> example(fn() {
+        assert_equal(<<216, 60, 223, 13>>, {
+          // 🌍
+          let codepoint = ffi.utf_codepoint(127_757)
+          <<codepoint:utf16_codepoint>>
+        })
+      }),
+    "UTF-32 codepoint"
+      |> example(fn() {
+        assert_equal(<<0, 1, 243, 13>>, {
+          // 🌍
+          let codepoint = ffi.utf_codepoint(127_757)
+          <<codepoint:utf32_codepoint>>
+        })
+      }),
   ]
 }