Testing FontLab Studio 5 macros
Test-driven development for FontLab Studio 5 Python macros and modules
FakeLab is a FontLab Studio 5 replacement for testing Python code.
Everything is only implemented so far as to make FontLab objects importable outside of FontLab Studio 5, and run tests.
Of course, nowadays you will run FakeLab in Python 3. You need to be aware that inside FontLab Studio 5, your Python scripts and modules will run in Python 2. You must make the scripts as future-proof as possible by importing the future:
from __future__ import absolute_import, print_function, unicode_literals
Still, it is easy to accidentally use Python-3-only language elements when developing with FakeLab outside FLS5.
The ideal solution would be to run all your scripts outside FLS5 using FakeLab’s Headless FontLab mode. This mode still needs lots of improvements, though.
The implementation of FakeLab is based on the invaluable Unofficial FontLab/Python API Reference, and from running scripts in FontLab Studio and checking what they do, apart from crashing the application.
Installation
When you have activated your virtual environment:
$ pip install -e .
FL is then importable outside of FontLab Studio:
from FL import fl, Font
# Make an empty font
f = Font()
# Add the font to the mock app
fl.Add(f)
# Close the font
fl.Close()
If you are running in a virtual environment, and need to make your FontLab modules importable, add a .pth file in your virtual environment’s site-packages directory:
# fl5modules.pth
/Users/<yourname>/Code/FLMacros/System/Modules
A word of caution
FakeLab is a work in progress, and only implemented as far as I needed it in my own scripts. I have to admit that the bulk of them still has no tests.
If you encounter a NotImplementedError while writing tests, this is where you can excel at helping to improve this project ;) I’ll be happy to accept your pull requests. Alternatively, open an issue.
Writing tests
Developing scripts without automated testing is really only for very small projects. To be sure of the outcomes of a module or script, you should always write tests. This is usually done using pytest.
Tests example
Let’s assume you have a FontLab script to select glyphs containing components. If you have your own tools collection for FontLab, this script may consist of two parts: One script that is listed in FontLab’s macro toolbar, and one Python module implementing the logic, which is called by the toolbar script.
Studio 5
+- Macros
+- Selection
+- Select Composites.py
+- System
+- Modules
+- fakeLabDemo
+- selection
+- __init__.py
+- composites.py
The Select Composites.py script looks like this:
#FLM: Select composites
# Studio 5/Macros/Selection/Select Composites.py
from fakeLabDemo.selection.composites import selectComposites
selectComposites(fl.font)
And the module:
# Studio 5/Macros/System/Modules/fakeLabDemo/selection/composites.py
from __future__ import absolute_import, division, print_function
from FL import fl
def getFontIndex(font):
"""
Get the index of the supplied font.
We must iterate through the open fonts and compare file names,
because the == operator can not compare the font objects directly.
(FL font objects get a different id() each time they are called)
:param font: A title for the dialog.
:type font: :py:class:`FL.Font`
"""
for i in range(len(fl)):
cf = fl[i]
if cf.file_name == font.file_name:
if font.file_name is None:
if (
cf.family_name == font.family_name
and cf.style_name == font.style_name
):
return (cf, i)
else:
return (cf, i)
# Font was not found, probably there are no open fonts
return (None, -1)
def setSelection(font, glyph_names):
"""
Set glyphs from the glyph_names list as selected in the font window.
"""
f, i = getFontIndex(font)
if i > -1:
fl.ifont = i
fl.Unselect()
for n in glyph_names:
fl.Select(n)
def selectComposites(font):
"""
Select composites in font.
"""
setSelection(
font,
[
glyph.name
for glyph in font.glyphs
if glyph.components
]
)
How can we be sure this script does what it is supposed to do? For pytest, we add another parallel folder structure to the existing structure:
Studio 5
+- Macros
+- Selection
+- Select Composites.py
+- System
+- Modules
+- fakeLabDemo
+- selection
+- __init__.py
+- composites.py
+- tests
+- fakeLabDemo
+- selection
+- composites_test.py
The file composites_test.py, which is named analogous to the module file it relates to, is where we will implement our tests:
# Studio 5/Macros/System/Modules/tests/fakeLabDemo/selection/composites_test.py
import pytest
from FL import fl, Component, Font, Glyph, Point
from fakeLabDemo.selection.composites import selectComposites
def test_selectComposites():
# Construct a fake FontLab font object
font = Font()
g = Glyph(1)
g.name = "A"
g.width = 500
g.unicode = 0x41
font.glyphs.append(g)
g = Glyph(1)
g.name = "dieresis"
g.width = 500
g.unicode = 0xA8
font.glyphs.append(g)
g = Glyph(1)
g.name = "Adieresis"
g.width = 500
g.unicode = 0xC4
g.components.append(Component(0))
g.components.append(Component(1, Point(0, 300)))
font.glyphs.append(g)
# Add the font to the FL object
fl.Add(font)
fl.UpdateFont()
# Run our script to be tested on the font
selectComposites(fl.font)
# You could save the modified font to VFB for later inspection.
# fl.font.Save("test_composites.vfb")
# Test if the correct glyphs have been selected
assert fl.Selected(0) == 0
assert fl.Selected(1) == 0
assert fl.Selected(2) == 1
# Close the fake font
fl.Close()
As you see, you can use the objects just as you would inside FontLab.
You can construct a minimal test font as shown in the example by using the FL Python API, or you can open an existing VFB file with Font().Open(path_to_vfb).
Invoke the test script in a Terminal window while your virtual environment is active:
cd "Studio 5/Macros/System/Modules"
python -m pytest tests/fakeLabDemo/selection/composites_test.py
If everything works out, you will see some output like this:
============================ test session starts ===============================
platform darwin -- Python 3.8.7, pytest-6.0.1, py-1.9.0, pluggy-0.13.1
rootdir: /Users/<yourname>/Code/fakelab
collected 1 item
tests/fakeLabDemo/selection/composites_test.py . [100%]
============================= 1 passed in 0.02s ================================