 { xoffset: 0, yoffset: 0, width: 4, height: 3,
        expectation: gl.INVALID_OPERATION, message: "height is not a multiple of 4" },
      { xoffset: 0, yoffset: 0, width: 3, height: 4,
        expectation: gl.INVALID_OPERATION, message: "width is not a multiple of 4" },
      { xoffset: 1, yoffset: 0, width: 4, height: 4,
        expectation: gl.INVALID_OPERATION, message: "xoffset is not a multiple of 4" },
      { xoffset: 0, yoffset: 1, width: 4, height: 4,
        expectation: gl.INVALID_OPERATION, m