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+<!--
+Copyright (c) 2019 The Khronos Group Inc.
+Use of this source code is governed by an MIT-style license that can be
+found in the LICENSE.txt file.
+-->
+
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="utf-8">
+<title>CopyTexSubImage2D partial destination texture test</title>
+<link rel="stylesheet" href="../../../resources/js-test-style.css"/>
+<script src="../../../js/js-test-pre.js"></script>
+<script src="../../../js/webgl-test-utils.js"></script>
+</head>
+<body>
+<div id="description"></div>
+<canvas id="canvas"></canvas>
+<div id="console"></div>
+
+<script>
+"use strict";
+description("Verifies that copyTexSubImage2D redefining part of the destination texture works as expected.");
+
+function runTest() {
+    var wtu = WebGLTestUtils;
+    var canvas = document.getElementById("canvas");
+    canvas.width = 256;
+    canvas.height = 256;
+    var gl = wtu.create3DContext(canvas);
+    // Try this test multiple times.
+    for (var ii = 0; ii < 10; ++ii) {
+        gl.clearColor(0.0, 1.0, 0.0, 1.0);
+        gl.clear(gl.COLOR_BUFFER_BIT);
+        var tex = gl.createTexture();
+        gl.bindTexture(gl.TEXTURE_2D, tex);
+        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
+        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
+        // Allocate a texture twice as tall as the canvas.
+        // Conceptually, it is filled with zeros.
+        gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, canvas.width, 2 * canvas.height,
+                      0, gl.RGBA, gl.UNSIGNED_BYTE, null);
+        // Copy the entire framebuffer into the top part of this texture.
+        gl.copyTexSubImage2D(gl.TEXTURE_2D, 0, 0, 0, 0, 0, canvas.width, canvas.height);
+        // Draw the texture back into the canvas.
+        var program = wtu.setupTexturedQuad(gl);
+        wtu.drawUnitQuad(gl);
+        gl.deleteProgram(program);
+        gl.deleteTexture(tex);
+        wtu.checkCanvasRect(gl, 0, 0, canvas.width, canvas.height / 2, [0, 255, 0, 255],
+                            "should be green");
+        wtu.checkCanvasRect(gl, 0, canvas.height / 2, canvas.width, canvas.height / 2, [0, 0, 0, 0],
+                            "should be transparent black");
+    }
+}
+
+runTest();
+
+debug("");
+var successfullyParsed = true;
+</script>
+<script src="../../../js/js-test-post.js"></script>
+
+</body>
+</html>