feature: add support for installing completions at package build time

[ghthor]

Enables installing the completions at build time (aka during package building) and also simplifies the management of completions in the long run as the only required modification to the shell rc file can be a single line.

I need some pointers on how to add this feature into the documentation, I wasn't able to figure it out but I also didn't give it 100%.

This feature makes the processing of installing the completions into the standard system locations at package build time line up with how the cobra framework does it as well as many other CLI frameworks.

For instance the following is from the nixpkg of a command that uses cobra.

https://github.com/nix-community/gomod2nix/blob/master/default.nix#L39

  postInstall = lib.optionalString (stdenv.buildPlatform == stdenv.targetPlatform) ''
    installShellCompletion --cmd gomod2nix \
      --bash <($out/bin/gomod2nix completion bash) \
      --fish <($out/bin/gomod2nix completion fish) \
      --zsh <($out/bin/gomod2nix completion zsh)
  '' + ''
    wrapProgram $out/bin/gomod2nix --prefix PATH : ${lib.makeBinPath [ go ]}
  '';

For comparison, the aws-sso-cli package would then do something like the following.

---
 pkgs/tools/admin/aws-sso-cli/default.nix | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/pkgs/tools/admin/aws-sso-cli/default.nix b/pkgs/tools/admin/aws-sso-cli/default.nix
index 998da596c06889..d9fc445c8bd929 100644
--- a/pkgs/tools/admin/aws-sso-cli/default.nix
+++ b/pkgs/tools/admin/aws-sso-cli/default.nix
@@ -23,7 +23,12 @@ buildGoModule rec {
     "-X main.Tag=nixpkgs"
   ];
 
-  postInstall = ''
+  postInstall = lib.optionalString (stdenv.buildPlatform == stdenv.targetPlatform) ''
+    installShellCompletion --cmd aws-sso \
+      --bash <($out/bin/aws-sso completions --source --shell=bash) \
+      --fish <($out/bin/aws-sso completions --source --shell=fish) \
+      --zsh <($out/bin/aws-sso completions --source --shell=zsh)
+  '' + ''
     wrapProgram $out/bin/aws-sso \
       --suffix PATH : ${lib.makeBinPath [ xdg-utils ]}
   '';

ghthor/nixpkgs@c7c2ea6

[synfinatic]

@ghthor , just so I'm clear, this change is specific for Nix?

[synfinatic]

@ghthor, you should be able to rebase & push and the builds should run properly now.

[ghthor]

@ghthor , just so I'm clear, this change is specific for Nix?

It is not. It would apply to any packaging system, though it may need an additional feature to override the executable path. For instance if we wanted to add a PKGBUILD to the AUR I believe we'd need to override the executable path as it wouldn't be the same at build time versus runtime after the package was installed; while with Nix the executable path is the same at build time as runtime.

But this is a general pattern that enables packagers to incorporate the shell completions into package builds. I just used nix in my example as it's my current target to get support for.

[ghthor]

Bump @synfinatic anything I can do to help get this merged?

[codecov]

Codecov Report

Attention: Patch coverage is 56.41026% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 80.32%. Comparing base (1d47cef) to head (ae4abdb).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #779      +/-   ##
==========================================
- Coverage   82.49%   80.32%   -2.16%     
==========================================
  Files          35       37       +2     
  Lines        3266     3405     +139     
==========================================
+ Hits         2694     2735      +41     
- Misses        504      595      +91     
- Partials       68       75       +7     

Files	Coverage Δ
internal/utils/fileedit.go	70.99% <45.45%> (-2.34%)	⬇️
internal/helper/helper.go	27.42% <60.71%> (ø)

... and 1 file with indirect coverage changes

---

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[synfinatic]

Sorry... been busy with non-SSO related things. Anyways, the proposed code change looks good, but do you mind adding some unit tests and an appropriate comment in the CHANGELOG.md file?

[synfinatic]

@ghthor FYI, i've enabled the build job to automatically run without approval for you. shouldn't be any more delays.

[ghthor]

I don't see any benefit to increasing the coverage of the tests for a bunch of toss it and return errors that have no handling behavior other than return. Do see any behavior remaining that would be worthwhile to add test cases for?

[ghthor]

I'm happy to work on improving coverage else where as a followup to this PR

[synfinatic]

Thanks for the PR and your patience @ghthor .