[css-properties-values-api] CSS.supports(property, value) behavior.

The two-parameter version of CSS.supports should return false if the value does not parse for the registered syntax of the property. BUG=641877 R=futhark@chromium.org Change-Id: I7a3ccbbd8ad465132bb44348919db19e837b5dd7 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1604268 Reviewed-by: Rune Lillesveen <futhark@chromium.org> Commit-Queue: Anders Hartvoll Ruud <andruud@chromium.org> Cr-Commit-Position: refs/heads/master@{#659919}
web-platform-tests · May 15, 2019 · d7afcb8 · d7afcb8
1 parent d04f026
commit d7afcb8
Showing 1 changed file with 42 additions and 0 deletions.
diff --git a/css/css-properties-values-api/conditional-rules.html b/css/css-properties-values-api/conditional-rules.html
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+<!DOCTYPE html>
+<link rel="help" href="https://drafts.css-houdini.org/css-properties-values-api-1/#conditional-rules" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<script>
+  CSS.registerProperty({
+    name: '--length',
+    syntax: '<length>',
+    initialValue: '0px',
+    inherits: false
+  });
+</script>
+
+<style>
+  #target { color: red; }
+  @supports(--length: green) {
+    #target { color: rgb(1, 2, 3); }
+  }
+</style>
+
+<div id=target></div>
+
+<script>
+
+test(function() {
+  let cs = getComputedStyle(target);
+  assert_equals(cs.getPropertyValue('color'), 'rgb(1, 2, 3)');
+}, '@supports should ignore registered syntax');
+
+test(function() {
+  assert_true(CSS.supports('--length: red'));
+  assert_true(CSS.supports('--length: 10px'));
+  assert_true(CSS.supports('--length: anything, really'));
+}, 'CSS.supports(conditionText) should ignore registered syntax');
+
+test(function() {
+  assert_false(CSS.supports('--length', 'red'));
+  assert_true(CSS.supports('--length', '10px'));
+}, 'CSS.supports(property, value) should parse against registered syntax');
+
+</script>