Use PR diff as base and revision

[atd]

In a setup where you are tracking the oas.yaml in git, you would expect to check the diff in the context of a pull request. This means you automatically set the following:

• base to the oas.yaml of the branch your pull request is on
• revision to the oas.yaml of the last commit of your pull request

This is the behavior of other actions like https://github.com/kamilkisiela/graphql-inspector

Any thoughts?

[mminklet]

Tried to do the same, unfortunately it's a deal breaker. Tried using checkout and supplying the path but it doesn't pick up changes. Tried giving it the blob url but doesn't play nicely with private repos

[mminklet]

My solution to use the oasdiff library separately rather than this action. Probably not the most efficient code but does the basics that we need for now

    runs-on: ubuntu-latest
    name: Check out and try oasdiff
    steps:
      - name: Set up Go 1.21.6
        uses: actions/setup-go@v5
        with:
          go-version: 1.21.6
          check-latest: true
          cache-dependency-path: backend/go.sum
      - name: code-checkout
        uses: actions/checkout@v2
        with:
          sparse-checkout: api-docs
          ref: ${{ github.base_ref }}
          path: base
      - name: code-checkout
        uses: actions/checkout@v4
        with:
          sparse-checkout: api-docs
          ref: ${{ github.head_ref }}
          path: head

      - name: install oasdiff
        run: |
          go install github.com/tufin/oasdiff@latest
      - name: run oasdiff diff
        run: |
          oasdiff diff ${{ github.workspace }}/base/api-docs/openapi.yaml ${{ github.workspace }}/head/api-docs/openapi.yaml
      - name: run oasdiff changelog
        run: |
          oasdiff breaking ${{ github.workspace }}/base/api-docs/openapi.yaml ${{ github.workspace }}/head/api-docs/openapi.yaml -f githubactions
      - name: run oasdiff breaking changes
        run: |
          oasdiff changelog ${{ github.workspace }}/base/api-docs/openapi.yaml ${{ github.workspace }}/head/api-docs/openapi.yaml -f githubactions

[marachimeno]

It is possible to achieve this behaviour when you check out both the base and head branches in your GH action script.
I have managed to do it as follows:

const checkoutBaseBranch: Step = {
  name: 'Checkout base branch',
  uses: 'actions/checkout@v4',
  with: {
    ref: '${{ github.event.pull_request.base.ref }}',
    path: 'base'
  }
}

const checkoutHeadBranch: Step = {
  name: 'Checkout head branch',
  uses: 'actions/checkout@v4',
  with: {
    ref: '${{ github.event.pull_request.head.ref }}',
    path: 'head'
  }
}

const checkBreakingChanges: Step = {
  name: 'Running OpenAPI Spec diff action',
  uses: 'oasdiff/oasdiff-action/breaking@main',
  with: {
    base: `base/${PATH}`,
    revision: `head/${PATH}`
  }
}

export default new Workflow(CHECK_OAS)
  .on('pull_request', { paths: ... })
  .addJob('check', {
    steps: [
      checkoutBaseBranch,
      checkoutHeadBranch,
      checkBreakingChanges
    ]
  })

[reuvenharrison]

This is supported via git refs. After checking out the repo and fetching the base branch, pass git refs directly to base and revision:

- uses: actions/checkout@v4
- run: git fetch --depth=1 origin ${{ github.base_ref }}
- uses: oasdiff/oasdiff-action/breaking@v0.0.34
  with:
    base: 'origin/${{ github.base_ref }}:openapi.yaml'
    revision: 'HEAD:openapi.yaml'

This automatically compares the spec on the PR's base branch against the spec on the PR's head commit — exactly the behaviour described in the issue. See the Spec paths section of the README for details.