[@Property] Failing to provide intialValue in registerProperty with non-universal syntax should throw

anttijk · anttijk · commit 6736a31764fa · 2023-01-13T23:29:58.000-08:00
https://bugs.webkit.org/show_bug.cgi?id=250556 <rdar://problem/104254311> Reviewed by Simon Fraser. * LayoutTests/imported/w3c/web-platform-tests/css/css-properties-values-api/register-property-expected.txt: * Source/WebCore/css/DOMCSSRegisterCustomProperty.cpp: (WebCore::DOMCSSRegisterCustomProperty::registerProperty): Throw is needed. Canonical link: https://commits.webkit.org/258909@main
diff --git a/LayoutTests/imported/w3c/web-platform-tests/css/css-properties-values-api/register-property-expected.txt b/LayoutTests/imported/w3c/web-platform-tests/css/css-properties-values-api/register-property-expected.txt
@@ -1,7 +1,7 @@
 
 PASS registerProperty requires a Dictionary type
 PASS registerProperty requires a name matching <custom-property-name>
-FAIL registerProperty only allows omitting initialValue if syntax is '*' assert_throws_dom: function "() => CSS.registerProperty({name: '--syntax-test-3', syntax: 'length', inherits: false})" did not throw
+PASS registerProperty only allows omitting initialValue if syntax is '*'
 PASS registerProperty fails for an already registered property
 PASS registerProperty requires inherits
 PASS Registering a property should not cause a transition
diff --git a/Source/WebCore/css/DOMCSSRegisterCustomProperty.cpp b/Source/WebCore/css/DOMCSSRegisterCustomProperty.cpp
@@ -51,6 +51,9 @@ ExceptionOr<void> DOMCSSRegisterCustomProperty::registerProperty(Document& docum
     if (!syntax)
         return Exception { SyntaxError, "Invalid property syntax definition."_s };
 
+    if (!syntax->isUniversal() && descriptor.initialValue.isNull())
+        return Exception { SyntaxError, "An initial value is mandatory except for the '*' syntax."_s };
+
     RefPtr<CSSCustomPropertyValue> initialValue;
     if (!descriptor.initialValue.isNull()) {
         CSSTokenizer tokenizer(descriptor.initialValue);
