Simplify test_utf. NFC (#24274)

- Use stringToUTFOnStack to avoid malloc and free
- Use separate params to `out` rather than using `join()`
- Use correct printf args to simplify C printf call
- Format JS to its more readable

Author: sbc100

test/core/test_utf.c

@@ -11,15 +11,11 @@
 
 int main() {
   char *c = "μ†ℱ ╋ℯ╳╋ 😇";
-  printf("%d %d %d %d %s\n", c[0] & 0xff, c[1] & 0xff, c[2] & 0xff, c[3] & 0xff,
-         c);
+  printf("%hhu %hhu %hhu %hhu %s\n", c[0], c[1], c[2], c[3], c);
   emscripten_run_script(
-      "var cheez = _malloc(100);"
-      "Module.stringToUTF8(\"μ†ℱ ╋ℯ╳╋ 😇\", cheez, 100);"
-      "out([UTF8ToString(cheez), Module.getValue(cheez, "
-      "'i8')&0xff, Module.getValue(cheez+1, 'i8')&0xff, "
-      "Module.getValue(cheez+2, 'i8')&0xff, Module.getValue(cheez+3, "
-      "'i8')&0xff].join(','));"
-      "_free(cheez);"
-      );
+    "var cheez = Module.stringToUTF8OnStack(\"μ†ℱ ╋ℯ╳╋ 😇\");"
+    "out(UTF8ToString(cheez), Module.getValue(cheez+0, 'i8')&0xff, "
+    "                         Module.getValue(cheez+1, 'i8')&0xff, "
+    "                         Module.getValue(cheez+2, 'i8')&0xff, "
+    "                         Module.getValue(cheez+3, 'i8')&0xff);");
 }

test/core/test_utf.out

@@ -1,2 +1,2 @@
 206 188 226 128 μ†ℱ ╋ℯ╳╋ 😇
-μ†ℱ ╋ℯ╳╋ 😇,206,188,226,128
+μ†ℱ ╋ℯ╳╋ 😇 206 188 226 128

test/test_core.py

@@ -5618,8 +5618,7 @@ def test_futimens(self):
   @no_minimal_runtime('MINIMAL_RUNTIME does not have getValue() and setValue() (TODO add it to a JS library function to get it in)')
   @requires_node  # only node handles utf well
   def test_utf(self):
-    self.set_setting('EXPORTED_FUNCTIONS', ['_main', '_malloc', '_free'])
-    self.set_setting('EXPORTED_RUNTIME_METHODS', ['getValue', 'setValue', 'UTF8ToString', 'stringToUTF8'])
+    self.set_setting('EXPORTED_RUNTIME_METHODS', ['getValue', 'setValue', 'UTF8ToString', 'stringToUTF8OnStack'])
     self.do_core_test('test_utf.c')
 
   def test_utf32(self):