gh issue artifact stack 8/10: Add edit - #14571

Part of the pull request stack tracked in #14563.

This adds gh issue artifact edit from #14526.

Description

Issue artifacts are Markdown documents and links attached to an issue. The previous pull requests added the gh issue artifact command group, list, view, delete, download and create. This one adds edit. It renames an artifact or replaces its content, and each edit saves a new version in the artifact's edit history:

$ gh issue artifact edit 142 2 --name 'OAuth callback plan v2'
✓ Updated artifact 2 (OAuth callback plan v2) on monalisa/monas-cafe#142

• --name renames the artifact. --body or --body-file replaces its content, and --body-file - reads standard input. A file never renames the artifact.
• The type never changes. A link's new content must be an http(s) URL, either from a .url Internet Shortcut file or as the whole content, with surrounding whitespace trimmed. A document never takes a .url file.
• --attach uploads images and videos and points the new content's references at them, as gh issue edit does. On its own, it appends them to the current content, like gh issue comment --edit-last --attach. A link can't take --attach.
• Types gh doesn't know are refused, as in view.
• Piped, the artifact gets one line with the same five columns as create, delete and download, with the status updated. The source column is the --body-file path, or - for standard input.

Flags and the new content are checked before any request, so a missing, binary or empty file fails without one. The checks that depend on the type run after the artifact's lookup, before anything is uploaded or saved.

The API client gains Update. It sends only the fields that change, so --name on its own leaves the content alone. create's --attach uploader moves to the shared package as NewUploader, unchanged, so both commands build it the same way.

How did you test this change?

I recorded the built gh editing two artifacts on one issue in bagtoad/issue-artifacts-demo, checking each edit with gh issue artifact view, whose edit history grows by one version with each save: a rename, new content from a file and from standard input, a link's new URL from --body and from a .url file, --attach replacing a reference and appending an image on its own, the three type errors, nothing to change, and piped output. It leaves out failed uploads and saves, a type gh doesn't know, pull requests and GitHub Enterprise Server.

Open chapters and agent notes

Key points

• A link's new content is checked before anything is saved. newBody works out what to save from the artifact's type. For a link, a .url path is read as a shortcut, and anything else must be a bare URL:

  if shared.IsShortcutFile(opts.BodyFile) {
  	// A .url file gives the URL on its URL= line
  	u, err := shared.ShortcutURL(*content)
  	...
  }
  // Anything else, from --body, a file or standard input, must be the URL itself
  u, ok := shared.HTTPURL(*content)
  if !ok {
  	return nil, fmt.Errorf("artifact %d is a link; its new content must be an http(s) URL or a .url file", a.Number)
  }

  HTTPURL is the strict check view and download already use, so edit can't save a link that download would refuse to write as a shortcut.

• --attach on its own starts from the current content. With no --body or --body-file, the files are attached to the body the artifact's lookup returned, and references in it resolve against the working directory.

• An upload can't be undone, so an artifact is saved if any of its files uploaded. This is the --attach rule create follows for each document:

  md, uploadResult, err := uploader.UploadAndAttach(context.Background(), *body, dir, opts.Assets)
  // Nothing uploaded, so nothing is lost by not saving
  if err != nil && uploadResult.Uploaded == 0 {
  	shared.PrintFailure(opts.IO, result, action, err)
  	return cmdutil.SilentError
  }
  // Otherwise the save goes ahead, and the upload error is the reason on its line
  body, uploadErr = &md, err

  An artifact saved with only some of its files keeps the status updated, with the upload error as its reason, through the same line as create. In a terminal, gh prints this on stderr and exits 1:

  ! Updated artifact 2 (OAuth callback plan) on monalisa/monas-cafe#142, but could not upload ./latte-art.png: rate limited; wait and try again
  

• A failed lookup or save is a result line. An artifact that doesn't exist gives X Failed to update artifact 9: Not Found, like delete, and piped, a failed line. Mistakes in what was asked stay plain errors, as [Design] gh issue artifact edit #14526 shows for the type errors, and so does a type gh doesn't know, as in view.

• No artifact URLs yet. [Design] gh issue artifact edit #14526 also names an artifact by its URL. The API doesn't return artifact URLs yet, as discussed in RFC: gh issue artifact #14529, so edit takes an issue and a number, and its help leaves URLs out. A later pull request in this stack will add them.

• --attach records the same telemetry event as the other --attach commands.

Notes for reviewers

Start with the edit run function, then newBody after it. TestEditRun runs each row in a temporary directory, with the client mock for artifact requests and HTTP stubs for uploads. It has rows for failed and partial uploads, failed lookups and saves, and a type gh doesn't know, which the recording can't show.

These messages aren't in #14526:

• --name cannot be blank and --body cannot be blank, as in create.
• failed to update artifact 2 from missing.md: no such file or directory, and the same form for a binary or empty file and for standard input.
• broken.url: no [InternetShortcut] section; pass the URL with `--body` instead, for a link's .url file that isn't a shortcut. The other .url errors match create's.
• X Failed to update artifact 9: Not Found, for an artifact that doesn't exist.
• The line above for an artifact saved with only some of its files.

Related issues:

• [Design] gh issue artifact edit #14526 is the edit design, with a screen for each scenario.
• RFC: gh issue artifact #14529 is the RFC for the command group. Its discussion covers artifact URLs.

Authorship and follow-up

Who wrote this:

• A human wrote it.
• An agent wrote it under close human direction.
• An agent wrote it independently, and no human has guided the implementation beyond the initial prompt.

Who answers review comments:

• @BagToad will read and reply directly. Name the account.
• An agent will draft replies and @BagToad will read them before they are posted.
• Nobody has explicitly committed to replying.