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diff --git a/testing/web-platform/tests/html/canvas/element/text/2d.text.drawing.style.letterSpacing.measure.html b/testing/web-platform/tests/html/canvas/element/text/2d.text.drawing.style.letterSpacing.measure.html
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+++ b/testing/web-platform/tests/html/canvas/element/text/2d.text.drawing.style.letterSpacing.measure.html
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+<!DOCTYPE html>
+<!-- DO NOT EDIT! This test has been generated by /html/canvas/tools/gentest.py. -->
+<title>Canvas test: 2d.text.drawing.style.letterSpacing.measure</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/html/canvas/resources/canvas-tests.js"></script>
+<link rel="stylesheet" href="/html/canvas/resources/canvas-tests.css">
+<body class="show_output">
+
+<h1>2d.text.drawing.style.letterSpacing.measure</h1>
+<p class="desc">Testing letter spacing with different length units</p>
+
+
+<p class="output">Actual output:</p>
+<canvas id="c" class="output" width="100" height="50"><p class="fallback">FAIL (fallback content)</p></canvas>
+
+<ul id="d"></ul>
+<script>
+var t = async_test("Testing letter spacing with different length units");
+_addTest(function(canvas, ctx) {
+
+  _assertSame(ctx.letterSpacing, '0px', "ctx.letterSpacing", "'0px'");
+  _assertSame(ctx.wordSpacing, '0px', "ctx.wordSpacing", "'0px'");
+  var width_normal = ctx.measureText('Hello World').width;
+
+  function test_letter_spacing(value, difference_spacing, epsilon) {
+    ctx.letterSpacing = value;
+    _assertSame(ctx.letterSpacing, value, "ctx.letterSpacing", "value");
+    _assertSame(ctx.wordSpacing, '0px', "ctx.wordSpacing", "'0px'");
+    width_with_letter_spacing = ctx.measureText('Hello World').width;
+    assert_approx_equals(width_with_letter_spacing, width_normal + difference_spacing, epsilon, "letter spacing doesn't work.");
+  }
+
+  // The first value is the letter Spacing to be set, the second value the
+  // change in length of string 'Hello World', note that there are 11 letters
+  // in 'hello world', so the length difference is always letterSpacing * 11.
+  // and the third value is the acceptable differencee for the length change,
+  // note that unit such as 1cm/1mm doesn't map to an exact pixel value.
+  test_cases = [['3px', 33, 0.1],
+               ['5px', 55, 0.1],
+               ['-2px', -22, 0.1],
+               ['1em', 110, 0.1],
+               ['-0.1em', -11, 0.1],
+               ['1in', 1056, 0.1],
+               ['-0.1cm', -41.65, 0.2],
+               ['-0.6mm', -24,95, 0.2]]
+
+  for (const test_case of test_cases) {
+    test_letter_spacing(test_case[0], test_case[1], test_case[2]);
+  }
+
+});
+</script>
+