chapter3-exercise-soft-hyphens-tests.md

Tests for WBE Chapter 3 Exercise Soft Hyphens

The soft hyphen character, written \N{soft hyphen} in Python, represents a place where the text renderer can, but doesn’t have to, insert a hyphen and break the word across lines. Add support for it. If a word doesn’t fit at the end of a line, check if it has soft hyphens, and if so break the word across lines. Remember that a word can have multiple soft hyphens in it, and make sure to draw a hyphen when you break a word. The word “super­cala­fraga­listic­expi­ala­do­shus” is a good test case.

Tests

Testing boilerplate:

>>> import wbemocks
>>> _ = wbemocks.socket.patch().start()
>>> _ = wbemocks.ssl.patch().start()
>>> _ = wbemocks.patch_canvas()
>>> import browser
>>> def test_layout(text):
...   dl = browser.Layout(browser.lex(text)).display_list
...   return wbemocks.normalize_display_list(dl)

Soft hyphens allow text to hint at where breaks can be inserted. If a word is too wide to fit on the current line and contains a soft hyphen it can be split and a literal hyphen placed at the break. For any given word, only one display list item should be generated per line.

>>> browser.set_parameters(WIDTH=128)
>>> test_layout("Hello\N{soft hyphen}World") #doctest: +NORMALIZE_WHITESPACE
[(13.0, 21.0, 'Hello-', Font size=16 weight=normal slant=roman style=None),
 (13.0, 41.0, 'World', Font size=16 weight=normal slant=roman style=None)]

If the word fits without splitting then no literal hyphens are present.

>>> browser.set_parameters(WIDTH=800)
>>> test_layout("Hello\N{soft hyphen}World")
[(13.0, 21.0, 'HelloWorld', Font size=16 weight=normal slant=roman style=None)]

When a soft hyphen is replaced with a literal hyphen you need to check that the text with the hyphen fits on the line.

>>> browser.set_parameters(WIDTH=90)
>>> test_layout("a\N{soft hyphen}b\N{soft hyphen}c\N{soft hyphen}d\N{soft hyphen}e") #doctest: +NORMALIZE_WHITESPACE
[(13.0, 21.0, 'abc-', Font size=16 weight=normal slant=roman style=None), 
 (13.0, 41.0, 'de', Font size=16 weight=normal slant=roman style=None)]

Sometimes a word may be so long that it needs to be split multiple times.

>>> browser.set_parameters(WIDTH=122)
>>> test_layout("multi\N{soft hyphen}word\N{soft hyphen}split") #doctest: +NORMALIZE_WHITESPACE
[(13.0, 21.0, 'multi-', Font size=16 weight=normal slant=roman style=None), 
 (13.0, 41.0, 'word-', Font size=16 weight=normal slant=roman style=None),
 (13.0, 61.0, 'split', Font size=16 weight=normal slant=roman style=None)]