CSS Writing Modes Test Coverage in March 2015

This INCOMPLETE report is prepared by fantasai. It summarizes, section by section, the test coverage of CSS Writing Modes Level 3 in March 2015.

Notes for further improvement are written in orange.

Missing tests are described in red.

Table of Contents

General Comments on Tests

• 6.25em is not a substitute for 100px. Font sizes for tests should be in pixels, to ensure alignment on pixel boundaries.
• Tests should indent contents of declaration blocks for readability.

3.1. Block Flow Direction: the writing-mode property

writing-mode Property Definition

The property definition table defines the syntax and defaults.

• Initial value: block-flow-direction-004
• Applies to: See table
• Inheritance: checked implicitly in a large number of tests

Vertical Box Layout

This next section defines that writing-mode specifies the block flow direction; the tests check this for various types of boxes.

This property specifies whether lines of text are laid out horizontally or vertically and the direction in which blocks progress. Possible values:

horizontal-tb

Top-to-bottom block flow direction. The writing mode is horizontal.

vertical-rl

Right-to-left block flow direction. The writing mode is vertical.

vertical-lr

Left-to-right block flow direction. The writing mode is vertical.

The writing-mode property specifies the block flow direction, which determines the ordering direction of block-level boxes in a block formatting context; the ordering direction of line boxes in a block container that contains inlines; the ordering direction of rows in a table; etc. By virtue of determining the stacking direction of line boxes, the writing-mode property also determines whether the line boxes' orientation (and thus the writing mode) is horizontal or vertical.

The principal writing mode of the document is determined by the writing-mode and direction values specified on the root element. [...] Like direction, the writing-mode value of the root element is also propagated to the initial containing block and sets the block flow direction of the initial block formatting context.

• Should make tests more complete by using content that includes all of: sibling blocks, bare inline content, block-in-inline split, wrapped-content blocks (not just one-line child blocks or just wrapped text). (This change would merge the two sets of tests.)
• Should use numbers instead of letters to check for unwanted bidi effects.
• Should have asserts be clearer wrt writing-mode on root vs. ancestor vs. box itself.
• Should use a smaller font size, e.g. 10px, to ensure test fits within narrow screen (600px max).

This next section defines some special box-type transformations when writing-mode of the parent and child differ.

If a box has a different block flow direction than its containing block:

• If the box has a specified display of inline, its display computes to inline-block. [CSS21]
• If the box has a specified display of run-in, its display computes to block. [CSS21]
• If the box is a block container, then it establishes a new block formatting context.

These tests check orthogonal writing modes. Need to also check behavior of parallel writing modes.

Need to check that direciton and text-orientation do not tirgger these effects; only writing-mode property itself does.

The content of replaced elements do not rotate due to the writing mode: images, for example, remain upright. However replaced content involving text (such as MathML content or form elements) should match the replaced element’s writing mode and line orientation if the UA supports such a vertical writing mode for the replaced content.