Bug 1523562 [wpt PR 15088] - Unclosed Constructs Are Valid, a=testonly

Automatic update from web-platform-tests Unclosed Constructs Are Valid Tests <https://github.com/w3c/csswg-drafts/issues/1933> -- Merge pull request #15088 from web-platform-tests/tabatkins-patch-6 Unclosed Constructs Are Valid -- wpt-commits: 7f2a09e08bb41532cd8d816da836e3dbe3100d42, 9b18bc8291eeb8ec670e14f9c465bff425cfdb5c wpt-pr: 15088
2019-02-01 11:40:05 +00:00 · 2019-02-01 11:40:05 +00:00 · c1982cc4fa
--- a/testing/web-platform/tests/css/css-syntax/unclosed-constructs.html
+++ b/testing/web-platform/tests/css/css-syntax/unclosed-constructs.html
@ -0,0 +1,36 @@
+<!doctype html>
+<title>Unclosed Constructs Are Valid</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<meta name="author" title="Tab Atkins-Bittner">
+<link rel=help href="https://drafts.csswg.org/css-syntax/#rule-defs">
+
+<!--
+Tests that unclosed constructs are valid and match grammars,
+because grammar-matching only sees the "block",
+not the opening/closing characters themselves.
+-->
+
+<script>
+
+function validSelector(str) {
+    try {
+        document.querySelector(str);
+        return true;
+    } catch(e) {
+        return false;
+    }
+}
+function shouldBeValid(str) {
+    test(()=>{
+        assert_true(validSelector(str));
+    }, `"${str}" is a valid selector`)
+}
+
+shouldBeValid("[foo]");
+shouldBeValid("[foo");
+shouldBeValid(":nth-child(1)");
+shouldBeValid(":nth-child(1");
+
+</script>