serhii.net

Recap

This is part two of 211209-1354 Python testing basics with poetry and pytest. Fixtures scopes work similarly to the various setup/teardown functions of unittest, can be per module/class/etc.

Failure

Expecting a test to fail

@pytest.mark.xfail(reason="Reason why it's supposed to fail")
def test_...

Expecting a test to raise an exception

For a specific exception, you assert that it raises that exception type and then can do asserts on the exception that is raised.

def test_whatever():
  with pytest.raises(Exception) as excinfo:
    raise Exception("oh no")
  assert str(excinfo.value) == "oh no"

Regex also works (example directly from pytest.raises() API Reference

>>> with pytest.raises(ValueError, match=r'must be \d+$'):
...     raise ValueError("value must be 42")

## Services (skipped, see below)
### Creating fixtures that get used automatically
```python
@pytest.fixture(autouse=True)
def skip_servicetest(request, run_services):
  if request....
    pytest.skip("skipped because X")

Using the filesystem

pyfakefs creates a fake filesystem that gets used transparently.

from pyfakefs.fake_filesystem import FakeFilesystem

@pytest.fixture
def common_fs(fs: FakeFilesystem):
  fs.create_dir(Path("/tmp/common"))
  fs.create_file("/tmp/common")

def test_filesystem_fixture(common_filesystem):
  assert os.path.exists("/tmp/common")
  assert os.path.exists("/tmp/not_there") == False

General hints

red-green-refactor

A development approach from TDD.

1. Red - Write a test, it fails
   • Forces us to think about what we want to develop and how do we want to use the interface we’re about to implement.
2. Green - Make it pass (as fast as possible)
   • If it’s simple, just type it
   • If it’s harder, make a note and write the quickest solution that makes the test pass
3. Refactor - Spend time to make the implementation correct.

F.I.R.S.T Principles

Tests should be:

• Fast (encourages us to run them frequently, which increases confidence in the code)
• Independent (not influence each other)
• Repeatable (in any environment)
• Self-validating (a failing test should give enough info about what’s wrong¹)
• Timely written (just before the production code)²

Arrange-Act-Assert (3A)

3A is a common pattern for structuring tests.

• Arrange -> Create objects / prepare the environment
• Act -> Simulate behaviour
• Assert -> Check the results

In a test this would look like this:

string = "ABc"

result = string.upper()

assert result == "ABC"

import this

A coworker reminded be of this gem; quoting him:

The order is important. My favourite one is ’explicit is better than implciit'

Had a big repo, wanted to clone only some folders.

The setup below automatically fetched the subfolders I added to the sparse-checkout set.

git clone --filter=blob:none --no-checkout --branch main ssh://git@me.me/my/repo.git
cd myrepo
git sparse-checkout init --cone
git sparse-checkout set "activitywatch" "friends" ".task" ".timewarrior"

https://gohugo.io/tools/search/

It boils down to creating an index (json) then using something to search in it client side

Once an index is built, Lunr seems the way to do with this: https://lunrjs.com/docs/lunr.Query.html#~Clause

It seems flexible enough, including ability to search inside taxonomies.

• BIOS
  • Swap FN and Ctrl if needed
  • F1-F12 as standard F keys

Dotfiles

• clone dotfiles to ~/.dotfiles for stow to work

Install stuff

CLI

# essentials
sudo apt install cowsay fortune-mod
sudo apt install vim-gtk3  # for clipboard support
# wm clipboard
sudo apt install i3 
sudo apt installxdotool maim xclip zenity 
# misc
sudo apt install jq tldr silversearcher-ag rofi xscreensaver 
sudo apt install blueman
sudo apt install tree stow
sudo apt install fish
sudo apt install taskwarrior timewarrior
sudo apt install arandr, autorandr
# if needed ensurepip
sudo apt install python3.12-venv
sudo apt install git git-lfs
sudo apt install tig
sudo apt install pavucontrol

#sudo apt install kitty
sudo apt install alacritty

sudo apt install htop
sudo apt install ncal # cal command

Other package managers

• don’t forget about uv task install
• gem
  • gem install friends
• brew
  • brew install hugo
  • brew install go-task
  • brew install asciiquariume
• npm
  • for npx pagefind (for hugo)
• golang-go

Etc

• Telegram, Signal
  • Disable all on-screen notifications; NB needed after each login?…
• Obsidian (dpkg works)
  • Citations extension
• Zotero
  • BetterBibTex extension
  • 231010-2007 A new attempt at Zotero and Obsidian

First changes

• chsh /usr/bin/fish
• SSH keys for Github & all Gitlabs:
  • Generating a new SSH key and adding it to the ssh-agent - GitHub Docs
  • https://github.com/settings/ssh/new
• Set up tlp if it’s a laptop
• Fonts
  • ~/.fonts should work, subdirectories possible
    • fc-cache -v tells you which dirs it goes through
  • fc-cache -f installs
  • Links:
    • GitHub - tonsky/FiraCode: Free monospaced font with programming ligatures & sudo apt install fonts-firacode

Misc

alias cal="ncal -w -A1 -M"  # week starts on monday, 1 months from now, show weeks

• Xscreensaver screensavers I hate
  • headroom
  • skulllop
  • ref: XScreenSaver: Screenshots

From SO¹, if both are JSON serializable objects, you can use json:

from json import loads, dumps
from collections import OrderedDict

def to_dict(input_ordered_dict):
    return loads(dumps(input_ordered_dict))

Qtile scripting

Scripting Commands — Qtile 0.1.dev50+ga708c8c.d20211209 documentation has a lot more interesting stuff than the ones exposed through “vanilla” config, finally figured out how to use them:

def test(qtile):
    qtile.cmd_to_layout_index(0)

# ...
Key([mod, ctrl], "apostrophe",  lazy.function(test))

It’s in the docu¹ but I missed its significance on first read, then saw hints in a github config².

The qtile object passed as the first argument is exactly the QTile from scripting.

Qtile switching to a layout by id

To parametrize it, you have to let it return a callable function:

def switch_to(ly_id: int):
    def cb(qtile):
        qtile.cmd_to_layout_index(ly_id)
    return cb

# ...
Key([mod, ctrl], "apostrophe",  lazy.function(switch_to(0))), 

More fun with qtile scripting

I don’t see this mentioned in the docu, but the attributes can be found in the source of libqtile.core.manager — Qtile 0.1.dev50+ga708c8c.d20211209 documentation.

If you mess up config.py and restart qtile and most of your keybindings aren’t working, if you’re lucky you still have a terminal open. From it, you can fix config.py, then restart via qtile shell -> restart().

Get screenshotting working through a hotkey. I need to screenshot an area of the screen, put the screenshot in a folder, and immediately open it.

In i3 had

bindsym Mod3+s --release exec scrot -s -e 'mv $f ~/s/screenshots && eog ~/s/screenshots/$f'

Nothing I tried worked (didn’t do anything weird):

Key([mod], "s", lazy.spawn(CONFIG_LOCATION + "screenshot.sh"))

Tracked it down to two main issues:

1. scrot works, scrot -s doesn’t. (Running the shell script directly from shell was fine!)
2. qtile doesn’t like variables in shell scripts

   # this works
   scrot -u -e 'thunar $f' "/tmp/shot.png"
   # this doesn't
   scrot -u -e 'thunar $f' "$SCREENSHOT_PATH/shot.png"
   

Decided to leave the first one alone, scrot -u gets the currently selected window, which generally is good enough for me.

The second one - first rewrote the script to get passed the target path as positional variable (surprisingly it worked!), then decided to do it python-only. As a bonus, copies the screenshot url to the clipboard.

# definition
copy_command = 'bash -c "echo {0} | xclip -selection c"'
# ...
def take_screenshot():
	SCREENSHOT_FILENAME = datetime.now().strftime("qtile_%y%m%d-%H%M%S%z")+"-$w$h.png"
	screenshot_path = D.SCREENSHOT_DIR +"/"+ SCREENSHOT_FILENAME
	command = f"scrot -u -e 'thunar $f && {Commands.copy_command.format('$f')}' {screenshot_path}"
	return command

#usage
Key([mod], "s", lazy.spawn(Commands.take_screenshot()))

(qtile-dotfiles/config.py at master · justinesmithies/qtile-dotfiles has escrotum as python module, errored out during install in the qtile venv and segfaulted on first run when installed outside of it.)

To add an item for the WM to the options shown on gdm startup:

1. Add its .desktop file to /usr/share/xsessions:

[Desktop Entry]
Name=qtile
Comment=Qtile
Exec=/home/me/.dotfiles/qtile/.config/qtile/startup.sh
Type=Application
X-LightDM-DesktopName=qtile
DesktopNames=qtile
Keywords=tiling;wm;windowmanager;window;manager;

2. sudo systemctl restart gdm.service¹