Update docsbuilder changelog add to handle PR fetch failures

[lcawl]

While testing the docs-builder changelog add command and attempting to pull PR information from a private repo, the command failed to fetch and did not generate a changelog even when I provided the minimal --title and --type. Better handling is required for situations where the fetch fails.

Summary

• Updated the docs-builder changelog add command to generate a basic changelog even when PR fetch fails.
• Added tests to verify that PR fetch failures are handled correctly

Behavior

• When --prs is provided and PR fetch fails:
  • Generate a basic changelog file
  • Use --title and --type if provided
    • If missing, comment out title/type in the output with TODO comments
  • Emit warnings indicating manual updates are needed

Examples

docs-builder changelog add --title "test title" --type enhancement --products cloud-hosted --prs 149106 --owner elastic --repo cloud

Originally this type of command failed to create a changelog and reported this error: Error: Failed to fetch PR information from GitHub for PR: 149106. Skipping this PR.

Now the command successfully creates a changelog with this warning: Warning: Failed to fetch PR information from GitHub for PR: 149106. Generating basic changelog with provided values.

If you omit the --title option, for example, you'll get another warning like this: Warning: Title is missing. The changelog will be created with title commented out. Please manually update the title field.

Changes

• Modified CreateSingleChangelog method:
  • When PR fetch fails, continue processing instead of returning an error
  • Track prFetchFailed to adjust validation behavior
  • Emit warnings instead of errors when title/type are missing after PR fetch failure
• Updated CreateChangelogsForMultiplePrs method:
  • Changed error to warning when PR fetch fails
  • Continue processing to generate changelogs even when PR info cannot be fetched
• Enhanced BuildChangelogData method:
  • Handle nullable title/type by using empty strings when null
• Updated GenerateYaml method:
  • Added parameters to track missing title/type
  • Comment out missing fields in the YAML output with TODO comments
  • Insert commented fields at the beginning of the YAML data section
• Fixed filename generation:
  • Handle missing title by using PR URL or "changelog" as fallback
• Updated mock setup to handle full PR URLs (not just PR numbers)
• Added cloud-serverless product to test configuration
• Fixed routing so single PRs go directly to CreateSingleChangelog
• Added blocking label check to CreateSingleChangelog for consistency

Tests

1. CreateChangelog_WithPrOptionButPrFetchFails_WithTitleAndType_CreatesChangelog

• When PR fetch fails but --title and --type are provided, a changelog is created using those values.

2. CreateChangelog_WithPrOptionButPrFetchFails_WithoutTitleAndType_CreatesChangelogWithCommentedFields

• When PR fetch fails and --title or --type are not provided, a changelog is created with commented title/type fields and warnings are emitted.

3. CreateChangelog_WithMultiplePrsButPrFetchFails_GeneratesBasicChangelogs

• When multiple PRs are provided and fetch fails, basic changelogs are still generated.

The tests verify that:

• Changelogs are created even when PR fetch fails
• Provided --title and --type values are used when available
• Missing title/type are commented out in the YAML output
• Appropriate warnings are emitted
• The behavior works for both single and multiple PRs

Outstanding work

I think there is likely a need for a way to supply GitHub tokens or other credentials necessary to access private repos.

Generative AI disclosure

1. Did you use a generative AI (GenAI) tool to assist in creating this contribution?

• Yes
• No

5. If you answered "Yes" to the previous question, please specify the tool(s) and model(s) used (e.g., Google Gemini, OpenAI ChatGPT-4, etc.).

Tool(s) and model(s) used: composer-1 agent