Refactor test to use do_runf and remove .out file

Author: subhaushsingh

test/jslib/test_jslib_custom_settings.out

@@ -353,13 +353,15 @@ def test_jslib_legacy(self):
   # the -jsDfoo=val syntax:
   # See https://github.com/emscripten-core/emscripten/issues/10580.
   def test_jslib_custom_settings(self):
-    self.cflags += ['--js-library', test_file('jslib/test_jslib_custom_settings.js'), '-jsDCUSTOM_JS_OPTION=1']
-    self.do_run_in_out_file_test('jslib/test_jslib_custom_settings.c')
-
-    self.run_process([EMCC, test_file('hello_world.c'), '-jsDCUSTOM_JS_OPTION=1', '-jsDCUSTOM_JS_OPTION=2'])
+    self.cflags += ['--js-library', test_file('jslib/test_jslib_custom_settings.js')]
 
     self.assert_fail([EMCC, '-jsDWASM=0'], 'cannot change built-in settings values with a -jsD directive')
 
+    self.do_runf('jslib/test_jslib_custom_settings.c', '1\n', cflags=['-jsDCUSTOM_JS_OPTION=1'])
+
+    # verify that the settings can be specified more than once, and that the last one wins.
+    self.do_runf('jslib/test_jslib_custom_settings.c', '2\n', cflags=['-jsDCUSTOM_JS_OPTION=1', '-jsDCUSTOM_JS_OPTION=2'])
+
   def test_jslib_native_deps(self):
     # Verify that memset (which lives in compiled code), can be specified as a JS library
     # dependency.

test/test_jslib.py

@@ -216,7 +216,7 @@ def parse_args(newargs):  # noqa: C901, PLR0912, PLR0915
   """
   should_exit = False
   skip = False
-  user_js_defines = set()
+  user_js_defines: dict[str, str] = {}
   LEGACY_ARGS = {'--js-opts', '--llvm-opts', '--llvm-lto', '--memory-init-file'}
   LEGACY_FLAGS = {'--separate-asm', '--jcache', '--proxy-to-worker', '--default-obj-ext',
                   '--embind-emit-tsd', '--remove-duplicates', '--no-heap-copy'}
@@ -576,11 +576,9 @@ def consume_arg_file():
         key, value = key.split('=')
       else:
         value = '1'
-      if key in settings.keys() and key not in user_js_defines:
+      if key in settings.keys() and key not in options.user_js_defines:
         exit_with_error(f'{arg}: cannot change built-in settings values with a -jsD directive. Pass -s{key}={value} instead!')
-      user_js_defines.add(key)
-      # Apply user -jsD settings
-      settings[key] = value
+      options.user_js_defines[key] = value
       newargs[i] = ''
     elif check_flag('-shared'):
       options.shared = True
@@ -869,5 +867,9 @@ def parse_arguments(args):
 
   # Apply -s args here (after optimization levels, so they can override them)
   apply_user_settings()
+  
+  # Apply -jsD defines last so they win over -s args
+  for key, value in options.user_js_defines.items():
+    settings[key] = value
 
   return newargs