btest: add assert whenl manual_reference argument is mistakenly set. NFC (#17458)

Author: sbc100

tests/common.py

@@ -1692,7 +1692,7 @@ def btest_exit(self, filename, assert_returncode=0, *args, **kwargs):
     return self.btest(filename, *args, **kwargs)
 
   def btest(self, filename, expected=None, reference=None,
-            reference_slack=0, manual_reference=False, post_build=None,
+            reference_slack=0, manual_reference=None, post_build=None,
             args=None, message='.', also_proxied=False,
             url_suffix='', timeout=None, also_wasm2js=False,
             manually_trigger_reftest=False, extra_tries=1,
@@ -1710,6 +1710,9 @@ def btest(self, filename, expected=None, reference=None,
       self.reftest(test_file(reference), manually_trigger=manually_trigger_reftest)
       if not manual_reference:
         args += ['--pre-js', 'reftest.js', '-sGL_TESTING']
+    else:
+      # manual_reference only makes sense for reference tests
+      assert manual_reference is None
     outfile = 'test.html'
     args += [filename, '-o', outfile]
     # print('all args:', args)

tests/test_browser.py

@@ -929,7 +929,7 @@ def post():
 </body>''')
       create_file('test.html', html)
 
-    self.btest('sdl_key_proxy.c', '223092870', args=['--proxy-to-worker', '--pre-js', 'pre.js', '-sEXPORTED_FUNCTIONS=_main,_one', '-lSDL', '-lGL'], manual_reference=True, post_build=post)
+    self.btest('sdl_key_proxy.c', '223092870', args=['--proxy-to-worker', '--pre-js', 'pre.js', '-sEXPORTED_FUNCTIONS=_main,_one', '-lSDL', '-lGL'], post_build=post)
 
   def test_canvas_focus(self):
     self.btest_exit('canvas_focus.c')
@@ -979,7 +979,7 @@ def post():
 
       create_file('test.html', html)
 
-    self.btest('keydown_preventdefault_proxy.cpp', '300', args=['--proxy-to-worker', '-sEXPORTED_FUNCTIONS=_main'], manual_reference=True, post_build=post)
+    self.btest('keydown_preventdefault_proxy.cpp', '300', args=['--proxy-to-worker', '-sEXPORTED_FUNCTIONS=_main'], post_build=post)
 
   def test_sdl_text(self):
     create_file('pre.js', '''