1 files changed, 75 insertions, 0 deletions
diff --git a/testing/web-platform/tests/css/css-contain/container-queries/at-container-style-parsing.html b/testing/web-platform/tests/css/css-contain/container-queries/at-container-style-parsing.html
new file mode 100644
index 0000000000..36fda2e366
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+++ b/testing/web-platform/tests/css/css-contain/container-queries/at-container-style-parsing.html
@@ -0,0 +1,75 @@
+<!doctype html>
+<title>@container: style queries parsing</title>
+<link rel="help" href="https://drafts.csswg.org/css-contain-3/#container-rule">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="support/cq-testcommon.js"></script>
+<div style="container-name:name">
+  <main id="main"></main>
+</div>
+<script>
+  setup(() => assert_implements_container_queries());
+
+  function cleanup_main() {
+    while (main.firstChild)
+      main.firstChild.remove();
+  }
+
+  function set_style(text) {
+    let style = document.createElement('style');
+    style.innerText = text;
+    main.append(style);
+    return style;
+  }
+
+  function test_rule_valid(query) {
+    test(t => {
+      t.add_cleanup(cleanup_main);
+      let style = set_style(`@container ${query} {}`);
+      assert_equals(style.sheet.rules.length, 1);
+    }, query);
+  }
+
+  function test_condition_invalid(condition) {
+    test(t => {
+      t.add_cleanup(cleanup_main);
+      let style = set_style(`@container name ${condition} {}`);
+      assert_equals(style.sheet.rules.length, 0);
+    }, condition);
+  }
+
+  // Tests that 1) the condition parses, and 2) is either "unknown" or not, as
+  // specified.
+  function test_condition_valid(condition, unknown) {
+    test(t => {
+      t.add_cleanup(cleanup_main);
+      let style = set_style(`
+        @container name ${condition} {}
+        @container name (${condition}) or (not (${condition})) { main { --match:true; } }
+      `);
+      assert_equals(style.sheet.rules.length, 2);
+      const expected = unknown ? '' : 'true';
+      assert_equals(getComputedStyle(main).getPropertyValue('--match'), expected);
+    }, condition);
+  }
+
+  function test_condition_known(condition) {
+    test_condition_valid(condition, false /* unknown */);
+  }
+
+  function test_condition_unknown(condition) {
+    test_condition_valid(condition, true /* unknown */);
+  }
+
+  test_condition_known('style(--my-prop: foo)');
+  test_condition_known('style(--my-prop: foo - bar ())');
+  test_condition_known('style(not ((--foo: calc(10px + 2em)) and ((--foo: url(x)))))');
+  test_condition_known('style((--foo: bar) or (--bar: 10px))');
+  test_condition_known('style(--my-prop:)');
+  test_condition_known('style(--my-prop: )');
+  test_condition_known('style(--foo: bar !important)');
+  test_condition_known('style(--foo)');
+
+  test_condition_unknown('style(--foo: bar;)');
+  test_condition_unknown('style(style(--foo: bar))');
+</script>