1 files changed, 85 insertions, 0 deletions
diff --git a/testing/web-platform/tests/intersection-observer/bounding-box.html b/testing/web-platform/tests/intersection-observer/bounding-box.html
new file mode 100644
index 0000000000..367243d558
--- /dev/null
+++ b/testing/web-platform/tests/intersection-observer/bounding-box.html
@@ -0,0 +1,85 @@
+<!DOCTYPE html>
+<meta name="viewport" content="width=device-width,initial-scale=1">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="./resources/intersection-observer-test-utils.js"></script>
+
+<style>
+pre, #log {
+  position: absolute;
+  top: 0;
+  left: 200px;
+}
+#root {
+  overflow: visible;
+  height: 200px;
+  width: 160px;
+  border: 8px solid black;
+}
+#target {
+  margin: 10px;
+  width: 100px;
+  height: 100px;
+  padding: 10px;
+  background-color: green;
+}
+</style>
+
+<div id="root">
+  <div id="target" style="transform: translateY(300px)"></div>
+</div>
+
+<script>
+var entries = [];
+var target;
+
+runTestCycle(function() {
+  target = document.getElementById("target");
+  assert_true(!!target, "target exists");
+  var root = document.getElementById("root");
+  assert_true(!!root, "root exists");
+  var observer = new IntersectionObserver(function(changes) {
+    entries = entries.concat(changes)
+  }, {root: root});
+  observer.observe(target);
+  entries = entries.concat(observer.takeRecords());
+  assert_equals(entries.length, 0, "No initial notifications.");
+  runTestCycle(step0, "First rAF.");
+}, "Test that the target's border bounding box is used to calculate intersection.");
+
+function step0() {
+  var targetBounds = clientBounds(target);
+  target.style.transform = "translateY(195px)";
+  runTestCycle(step1, "target.style.transform = 'translateY(195px)'");
+  checkLastEntry(entries, 0, targetBounds.concat(0, 0, 0, 0, 8, 184, 8, 224, false));
+}
+
+function step1() {
+  var targetBounds = clientBounds(target);
+  target.style.transform = "translateY(300px)";
+  runTestCycle(step2, "target.style.transform = 'translateY(300px)'");
+  checkLastEntry(entries, 1, targetBounds.concat(26, 146, 221, 224, 8, 184, 8, 224, true));
+}
+
+function step2() {
+  var targetBounds = clientBounds(target);
+  target.style.transform = "";
+  target.style.zoom = "2";
+  runTestCycle(step3, "target.style.zoom = 2");
+  checkLastEntry(entries, 2, targetBounds.concat(0, 0, 0, 0, 8, 184, 8, 224, false));
+}
+
+function step3() {
+  var targetBounds = clientBounds(target);
+  var intersectionWidth = (
+      176  // root width including border
+      -8   // root left border
+      -20  // target left margin * target zoom
+  ) / 2;   // convert to target's zoom factor.
+  var intersectionHeight = (216 - 8 - 20) / 2;
+  var intersectionRect = [targetBounds[0], targetBounds[0] + intersectionWidth,
+                          targetBounds[2], targetBounds[2] + intersectionHeight];
+  checkLastEntry(entries, 3, targetBounds.concat(intersectionRect).concat(8, 184, 8, 224, true));
+}
+
+</script>