chromium/third_party/blink/web_tests/fast/inline/br-client-rect.html

<html>
  <head>
    <script src="../../resources/js-test.js"></script>
    <script>
      description("getBoundingClientRect() called on a &lt;br&gt; returns a zero-width and -height rect positioned at the end of the preceding line of text, on the baseline of the text.");

      function runTest()
      {
	br = document.getElementById("br")
	brRect = br.getBoundingClientRect();
        brRects = br.getClientRects();
	precedingSpanRect = br.previousSibling.getBoundingClientRect();

	shouldBe("brRect.width", "0");
	shouldBe("brRect.height", "0");
	shouldBe("brRect.left", "precedingSpanRect.right");
	shouldBeGreaterThan("brRect.top", "precedingSpanRect.top");
	shouldBeGreaterThan("precedingSpanRect.bottom", "brRect.top");

        shouldBe("brRects.length", "1");
        shouldBe("brRects[0].left", "brRect.left");
        shouldBe("brRects[0].top", "brRect.top");
        shouldBe("brRects[0].width", "brRect.width");
        shouldBe("brRects[0].height", "brRect.height");
      }

      window.onload = runTest;
    </script>
  </head>
  <body>
    <p>Filler text.</p>
    <p><span>There's a line break element at the end of this sentence.</span><br id="br">
       <span>Here is the second line.</span></p>
  </body>
</html>