feat: allow updater to target non-default branches

Add support for `target-branch` input parameter to allow dependency
updates on branches other than the repository's default branch.
This enables updating alpha, beta, or version-specific branches.

- Add `target-branch` input parameter to action.yml
- Modify base branch detection to use target-branch when provided
- Update README with parameter documentation and usage example
- Add workflow test for target-branch functionality

Fixes #87

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: vaind

.github/workflows/workflow-tests.yml

@@ -73,6 +73,70 @@ jobs:
 
           echo "✅ PR creation scenario validation passed!"
 
+  # Test target-branch functionality - should use specified branch as base
+  updater-target-branch:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run updater action with target-branch
+        id: updater
+        uses: ./updater
+        with:
+          path: updater/tests/sentry-cli.properties
+          name: TARGET-BRANCH-TEST-DO-NOT-MERGE
+          pattern: '^2\.0\.'
+          target-branch: test-branch
+          pr-strategy: update
+          api-token: ${{ github.token }}
+
+      - name: Validate target-branch outputs
+        env:
+          BASE_BRANCH: ${{ steps.updater.outputs.baseBranch }}
+          ORIGINAL_TAG: ${{ steps.updater.outputs.originalTag }}
+          LATEST_TAG: ${{ steps.updater.outputs.latestTag }}
+          PR_URL: ${{ steps.updater.outputs.prUrl }}
+          PR_BRANCH: ${{ steps.updater.outputs.prBranch }}
+        run: |
+          echo "🔍 Validating target-branch scenario outputs..."
+          echo "Base Branch: '$BASE_BRANCH'"
+          echo "Original Tag: '$ORIGINAL_TAG'"
+          echo "Latest Tag: '$LATEST_TAG'"
+          echo "PR URL: '$PR_URL'"
+          echo "PR Branch: '$PR_BRANCH'"
+
+          # Validate base branch is the specified target-branch
+          if [[ "$BASE_BRANCH" != "test-branch" ]]; then
+            echo "❌ Expected base branch 'test-branch', got '$BASE_BRANCH'"
+            exit 1
+          fi
+
+          # Validate original tag is expected test value
+          if [[ "$ORIGINAL_TAG" != "2.0.0" ]]; then
+            echo "❌ Expected original tag '2.0.0', got '$ORIGINAL_TAG'"
+            exit 1
+          fi
+
+          # Validate latest tag is a valid version
+          if [[ ! "$LATEST_TAG" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+            echo "❌ Latest tag '$LATEST_TAG' is not a valid version format"
+            exit 1
+          fi
+
+          # Validate PR URL format
+          if [[ ! "$PR_URL" =~ ^https://github\.com/getsentry/github-workflows/pull/[0-9]+$ ]]; then
+            echo "❌ PR URL '$PR_URL' is not a valid GitHub PR URL"
+            exit 1
+          fi
+
+          # Validate PR branch format
+          if [[ "$PR_BRANCH" != "deps/updater/tests/sentry-cli.properties" ]]; then
+            echo "❌ Expected PR branch 'deps/updater/tests/sentry-cli.properties', got '$PR_BRANCH'"
+            exit 1
+          fi
+
+          echo "✅ Target-branch scenario validation passed!"
+
   # Test no-change scenario - should detect no updates needed
   updater-no-changes:
     runs-on: macos-latest

updater/README.md

@@ -82,6 +82,18 @@ jobs:
           path: vendor/dependencies.cmake#googletest
           name: GoogleTest
           api-token: ${{ secrets.CI_DEPLOY_KEY }}
+
+  # Update dependencies on a non-default branch (e.g., alpha, beta, or version branches)
+  cocoa-v7:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: getsentry/github-workflows/updater@v3
+        with:
+          path: modules/sentry-cocoa
+          name: Cocoa SDK
+          target-branch: v7
+          pattern: '^1\.'  # Limit to major version '1'
+          api-token: ${{ secrets.CI_DEPLOY_KEY }}
 ```
 
 ## Inputs
@@ -118,6 +130,10 @@ jobs:
   Can be either of the following:
   * `create` (default) - create a new PR for new dependency versions as they are released - maintainers may merge or close older PRs manually
   * `update` - keep a single PR that gets updated with new dependency versions until merged - only the latest version update is available at any time
+* `target-branch`: Branch to use as base for dependency updates. Defaults to repository default branch if not specified.
+  * type: string
+  * required: false
+  * default: '' (uses repository default branch)
 * `api-token`: Token for the repo. Can be passed in using `${{ secrets.GITHUB_TOKEN }}`.
   If you provide the usual `${{ github.token }}`, no followup CI will run on the created PR.
   If you want CI to run on the PRs created by the Updater, you need to provide custom user-specific auth token.

updater/action.yml

@@ -29,6 +29,10 @@ inputs:
     description: 'How to handle PRs - can be either "create" (create new PRs for each version) or "update" (keep single PR updated with latest version)'
     required: false
     default: 'create'
+  target-branch:
+    description: 'Branch to use as base for dependency updates. Defaults to repository default branch if not specified.'
+    required: false
+    default: ''
   api-token:
     description: 'Token for the repo. Can be passed in using {{ secrets.GITHUB_TOKEN }}'
     required: true
@@ -122,8 +126,13 @@ runs:
       env:
         PR_STRATEGY: ${{ inputs.pr-strategy }}
         DEPENDENCY_PATH: ${{ inputs.path }}
+        TARGET_BRANCH: ${{ inputs.target-branch }}
       run: |
-        $mainBranch = $(git remote show origin | Select-String "HEAD branch: (.*)").Matches[0].Groups[1].Value
+        if ([string]::IsNullOrEmpty($env:TARGET_BRANCH)) {
+            $mainBranch = $(git remote show origin | Select-String "HEAD branch: (.*)").Matches[0].Groups[1].Value
+        } else {
+            $mainBranch = $env:TARGET_BRANCH
+        }
         $prBranch = switch ($env:PR_STRATEGY)
         {
             'create' { "deps/$env:DEPENDENCY_PATH/${{ steps.target.outputs.latestTag }}" }