pull-request-diff-analyzer

Pull Request Diff Analyzer

Analyze a git diff or PR to detect the change type and extract acceptance criteria for manual testing. Analysis only — never modify code.

Step 1: Detect Branch Context and Scope

Get the current branch:

git branch --show-current

Detect the base branch, in order:

1. From PR context (preferred). If a PR number is known:

gh pr view {PR_NUMBER} --json baseRefName

baseRefName in the response is the PR's base branch.

• If the base branch cannot be detected, ask the user to specify it.

Get changed files:

git diff {BASE_BRANCH}...HEAD --name-only

For uncommitted local changes only:

git diff --name-only

For a GitHub PR with full diff view:

gh pr diff {PR_NUMBER}

Skip to Step 3 with a short summary only (no acceptance criteria) if:

• Current branch is master, main, stable, or the detected default branch in baseRefName.
• No files changed.
• All changes are non-source-code updates:
  • documentation/requirements (*.md, docs/**)
  • test updates and test docs (*.test.md, test-flows/**, tests/e2e)
  • CI/CD and infrastructure config (.github/workflows/**, Jenkinsfile)
  • lint/formatter/tooling configs
  • dependency version bumps without behavior changes
• No application/source code behavior changed.

Proceed to Step 2 if source code changed (src/**, lib/**, app/**, or root .ts/.js/.tsx/.jsx/.java/.py/.go/.rb/.php/.cs/.kt/.swift/.rs, etc).

Step 2: Analyze PR Context and Files

Get PR details:

gh pr view {PR_NUMBER} --json title,body,comments,reviews,issues

Extract testing-relevant info:

• Title — feature/fix name, affected component.
• Description — criteria, test scenarios.
• Comments — test notes, edge cases, reproductions.

Analyze source code files only:

• Directories: src/**, lib/**, app/**, controllers/**, services/**, models/**, pages/**, components/**, handlers/**, modules/**, etc.
• Extensions: .ts, .js, .tsx, .jsx, .java, .py, .go, .rb, .php, .cs, .kt, .swift, .rs
• Skip configs, dependencies, tests, docs, migrations, and other files not related to source code.

Detect PR type:

• Feature — new files, endpoints, components, modules.
• Fix — bug fixes, patches, hotfixes (check commits for "fix", "bug", "hotfix").
• Refactor — code restructure without behavior change.

Optional: scan-automation-project

Do not run scan-automation-project by default. Run it only when extra project context adds clear value before writing acceptance criteria.

Run it if:

• The PR introduces new functionality or a significant feature change.
• You need to check whether similar manual tests already exist.
• The user explicitly asks ("check for duplicates", "what tests already exist", or similar).

Skip it if:

• The PR is a small fix or minor UI/component update.
• The diff already gives enough context to write ACs confidently.
• Changes are limited to docs, requirements, tests, configs, or non-source-code updates.
• The project does not appear to contain manual tests.
• Existing test inventory is not relevant for the requested task.

If it is unavailable:

• Continue without checking existing tests.
• Add this note to the AC output: Manual test inventory not checked — verify existing tests manually if needed.

Use scan results only to:

• Avoid duplicating existing manual test cases.
• Understand project structure, frameworks, and test organization.
• Improve relevance and consistency of generated acceptance criteria.

Step 3: Summary with Acceptance Criteria

Output format:

## PR Diff Summary

**PR Type:** ... (feature | fix | refactor)
**Branch:** ... (branch name, e.g. feature/user-auth)
**Changes:** ... (one sentence describing the overall purpose of this PR)
**Affected Files:**
- ... (bullet list of all affected files in this PR)

**Impacted Areas:**
- ... (1-3 bullets, only real impacted files/areas in the PR)

**Acceptance Criteria:**
- action to perform → expected result
- ...

Summary rules:

• Keep the summary concise and high-level.
• "Changes" is ONE sentence. Not a paragraph.
• "Impacted Areas" lists only meaningful business or technical impact.
• Omit empty sections instead of writing None or N/A.
• Acceptance criteria MUST be testable and user-oriented.
• Avoid generic statements like "code cleanup", "minor fixes", or "various improvements".
• Do NOT describe implementation details line-by-line.