A tool for comparing transitive dependencies in two deps.edn files.

Certainly, the Clojure ecosystem does not strictly follow SemVer (Spec-ulation), and if there are no concrete benefits, it is recommended not to update dependencies. However, when it becomes necessary to replace an artifact, you need to be extremely careful, especially when implicit transitive dependencies change, as compatibility issues may arise.

For example, consider the following dependency tree:

+-----+     +--------+     +--------+
|  A  | --> | B(1.0) | --> | C(1.0) |
+-----+     +--------+     +--------+
      \     +--------+     +--------+
       +--> | D(1.0) | --> | C(1.0) |
            +--------+     +--------+

Let's assume a situation where we need to update dependency B:

+-----+     +--------+     +--------+
|  A  | --> | B(2.0) | --> | C(2.0) |
+-----+     +--------+     +--------+
      \     +--------+     +--------+
       +--> | D(1.0) | --> | C(1.0) |
            +--------+     +--------+

In this scenario, B internally updated C to 2.0. If we haven't explicitly specified the version of C, there is no way to guarantee that D will work correctly (See Dep selection).

But it's good to know that such potential risks can be detected in advance. deps-diff is a GitHub Action created for this purpose.

Just create a .github/workflows/deps-diff.yml file as follows.

name: Notify dependency diff

on:
  pull_request:
    paths:
      - 'deps.edn' # only watch this

jobs:
  notify:
    runs-on: ubuntu-latest
    steps:
      - name: Diff dependencies
        id: diff
        uses: namenu/deps-diff@main
        with:
          format: markdown
          aliases: "[:test]"

      - uses: marocchino/sticky-pull-request-comment@v2
        if: ${{ steps.diff.outputs.exit_code != 0 }}
        with:
          header: deps-diff # Creates a collapsed comment with the report
          message: |
            ### `deps.edn` dependency changes

            ${{ steps.diff.outputs.deps_diff }}

This workflow will comment on your PR as shown below.

• deps_diff - The name of the outlet where the execution result is output. Use it along with the action's id in your workflow.
• exit_code - 0 if equal or else 1.