Add support for Nix build environment

[m15a]

related: none

A small contribution for Nix users to indicate if nix develop shell is activated in their prompt.

How to test pre-release?

☠️ Feature can be unstable and break your prompt!

fisher install m15a/pure@feat/nixdevshell   # branch name
set --universal pure_symbol_nixdevshell_prefix ❄️
mkdir /tmp/some_nix_project
nix flake init             # nix flake is required
echo 'use flake' > .envrc  # direnv and nix-direnv is required
direnv allow

Then your prompt looks like

❄impure ❯

First contribution?

Check the 👍 Contribute section and the contributing guide.

Specs

New config in conf.d/pure.fish

_pure_set_default pure_enable_nixdevshell true
_pure_set_default pure_symbol_nixdevshell_prefix "❄️"
_pure_set_default pure_color_nixdevshell_prefix brblue
_pure_set_default pure_color_nixdevshell_status pure_color_mute

Documentation

Usage

❯ set --universal pure_enable_nixdevshell true            # enable/disable this feature
❯ set --universal pure_symbol_nixdevshell_prefix ❄️       # set your favorite prefix icon
❯ set --universal pure_color_nixdevshell_prefix brblue  # set your favorite color for prefix symbol
❯ set --universal pure_color_nixdevshell_status pure_color_mute  # set your favorite color for nix dev shell status

Acceptance Checks

• documentation is up-to-date:
  • features list ;
  • Prompt Symbol ;
  • 🔌 Features' Flags ;
• feature flag is present in conf.d/pure.fish ;
• symbol is present in conf.d/pure.fish ;
• tests are passing (I can help you 🤗 ):
  • config are tested (cf. tests/_pure.test.fish) ;
  • feature is covered ;
• customization is available ;
• feature is implemented.

[edouard-lopez]

Thanks for the submission!

As it's an OS-specific feature, I won't enable it by default as it could impact other OSes (see comments).

Check out tests/_pure.test.fist to see how to test your feature settings:

pure/tests/_pure.test.fish

Lines 318 to 328 in 586869b

	@test "configure: pure_enable_k8s" (
	set --erase pure_enable_k8s
	source (status dirname)/../conf.d/pure.fish
	echo $pure_enable_k8s
	) = false
	@test "configure: pure_symbol_k8s_prefix" (
	set --erase pure_symbol_k8s_prefix
	source (status dirname)/../conf.d/pure.fish
	echo $pure_symbol_k8s_prefix
	) = "☸"

Then you can have a look at tests/_pure_prompt_k8s.test.fish to see how you can test the feature itself
https://github.com/pure-fish/pure/blob/586869bdf0f336d8fdcc4efd4a169a9f53a10a36/tests/_pure_prompt_k8s.test.fish

When that's done, we will need to restrict executions of the feature's tests in CI to the Nix job only, i.e detecting the OS with uname -s

pure/tests/_pure_is_inside_container.test.fish

Lines 77 to 78 in 586869b

	if test (uname -s) = Linux
	@test "_pure_is_inside_container: detect with pid method" (

[m15a]

When that's done, we will need to restrict executions of the feature's tests in CI to the Nix job only, i.e detecting the OS with uname -s

As I mentioned above, Nix is not only available on NixOS. So IMHO we don't need to restrict CI tests.

[m15a]

I've introduced another config variable so that one can customize colors of prefix symbol (by pure_color_nixdevshell_prefix) and nix dev shell status (by pure_color_nixdevshell_status).

[m15a]

Because on my system bash is at different path, I modified makefile:

diff --git a/makefile b/makefile
index a4368e5..6822660 100644
--- a/makefile
+++ b/makefile
@@ -1,7 +1,7 @@
 #!/usr/bin/make -sf

 # force use of Bash
-SHELL := /bin/bash
+SHELL := /usr/bin/env bash
 INTERACTIVE=true

and then ran tests using docker:

make build-pure-on FISH_VERSION=3.6.4
make test-pure-on FISH_VERSION=3.6.4

All tests passed.

[kothavade]

@m15a would you be willing to add a feature where only the icon is shown, but the status text (eg impure) is not? i like the visual feedback of the icon, but generally do not need the actual output of IN_NIX_SHELL.

i can also send a separate PR for that once this is merged if @edouard-lopez is okay with the added feature, but having it be in this PR would be easier.

[edouard-lopez]

Could you add the makefile change, it's a more robust approach. I would prefer another PR to keep them small.

I would look at this one Thursday, thanks for your patience

[edouard-lopez]

@m15a Note that I renamed the color variable

-pure_color_nixdevshell_status
+pure_color_nixdevshell_symbol

c6e59a3

[m15a]

@edouard-lopez Thanks!!