The tests make a number of assumptions of the user agent, and new tests can freely rely on these assumptions being true:

  • The device is a full-color device.
  • The device has a viewport width of at least 800px.
  • The UA imposes no minimum font size.
  • The medium font-size computes to 16px.
  • The canvas background is white.
  • The initial value of color is black.
  • The user stylesheet is empty (except where indicated by the tests).
  • The device is interactive and uses scroll bars.
  • The device has the Ahem font installed.
  • The HTML div element is assigned display: block; and no other property declaration.
  • The HTML span element is assigned display: inline; and no other property declaration.
  • The HTML p element is assigned display: block;
  • The HTML li element is assigned display: list-item;
  • The HTML table elements table, tbody, tr, and td are assigned the display values table, table-row-group, table-row, and table-cell, respectively.
  • The UA implements reasonable line-breaking behavior; e.g., it is assumed that spaces between alphanumeric characters provide line breaking opportunities and that UAs will not break at every opportunity, but only near the end of a line unless a line break is forced.

Tests for printing behavior make some further assumptions:

  • The UA is set to print background colors and, if it supports graphics, background images.
  • The UA implements reasonable page-breaking behavior; e.g., it is assumed that UAs will not break at every opportunity, but only near the end of a page unless a page break is forced.