feat: report the pull request's commit when CI checks out a merge commit

.github/scripts/check-pull-request-commit.js

@@ -0,0 +1,35 @@
+'use strict'
+
+// Runs commitInfo on the checkout that actions/checkout makes for a
+// pull_request event: GitHub's merge commit refs/pull/N/merge.
+//
+// EXPECTED_COMMIT=head: commitInfo reports the pull request's last commit
+// EXPECTED_COMMIT=checkout: commitInfo reports the merge commit, as before
+
+const assert = require('assert')
+const { execFileSync } = require('child_process')
+const { commitInfo } = require('../../src')
+
+const headSha = process.env.HEAD_SHA
+const expected = process.env.EXPECTED_COMMIT || 'head'
+
+const git = (...args) =>
+  execFileSync('git', args, { encoding: 'utf8' }).replace(/\n$/, '')
+
+const checkoutSha = git('rev-parse', 'HEAD')
+assert.notStrictEqual(checkoutSha, headSha, 'expected the merge commit')
+
+commitInfo()
+  .then(info => {
+    console.log(info)
+    const sha = expected === 'head' ? headSha : checkoutSha
+    assert.strictEqual(info.sha, sha)
+    assert.strictEqual(info.message, git('show', '-s', '--pretty=%B', sha))
+    assert.strictEqual(info.author, git('show', '-s', '--pretty=%an', sha))
+    assert.strictEqual(info.email, git('show', '-s', '--pretty=%ae', sha))
+    console.log(`commitInfo reported ${expected} commit ${sha}`)
+  })
+  .catch(e => {
+    console.error(e)
+    process.exit(1)
+  })

.github/workflows/pull-request.yml

@@ -0,0 +1,48 @@
+name: Pull request commit
+on: pull_request
+
+# the job runs code from the pull request
+permissions:
+  contents: read
+
+jobs:
+  commit-info:
+    name: commitInfo (${{ matrix.name }})
+    runs-on: ubuntu-latest
+    container: ${{ matrix.container }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: default checkout
+            fetch-depth: 1
+            expected: head
+          - name: full clone
+            fetch-depth: 0
+            expected: head
+          - name: git 2.25
+            fetch-depth: 1
+            expected: head
+            container: mcr.microsoft.com/playwright:v1.28.1-focal
+          - name: fetch disabled
+            fetch-depth: 1
+            expected: checkout
+            disable-fetch: 'true'
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: ${{ matrix.fetch-depth }}
+      - uses: actions/setup-node@v4
+        if: ${{ !matrix.container }}
+        with:
+          node-version: 16
+      # the checkout belongs to another user than the container's root
+      - if: ${{ matrix.container }}
+        run: git config --global --add safe.directory "$GITHUB_WORKSPACE"
+      - run: git --version && node --version
+      - run: npm ci --ignore-scripts
+      - run: node .github/scripts/check-pull-request-commit.js
+        env:
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+          EXPECTED_COMMIT: ${{ matrix.expected }}
+          CURRENTS_DISABLE_HEAD_COMMIT_FETCH: ${{ matrix.disable-fetch }}

README.md

@@ -5,7 +5,7 @@ Collects Git commit info from git CLI
 
 ## Install
 
-Requires [Node](https://nodejs.org/en/) version 6 or above.
+Requires [Node](https://nodejs.org/en/) version 8 or above.
 
 ```sh
 npm install --save @currents-dev/commit-info
@@ -37,6 +37,24 @@ Notes:
 - If a command fails, returns `null` for each property
 - If you need to debug, run with `DEBUG=commit-info` environment variable.
 
+## Pull request builds
+
+On pull request builds many CI providers check out a commit that merges the pull request into its target branch. GitHub Actions, for example, checks out `refs/pull/<number>/merge`, whose message is `Merge <sha> into <sha>`.
+
+When the checked-out commit is such a merge, `commitInfo` reports the pull request's last commit instead: its `sha`, `message`, `email`, `author` and `timestamp`. It finds that commit in:
+
+- GitHub Actions: `pull_request.head.sha` in the event file (`GITHUB_EVENT_PATH`)
+- GitLab merged results pipelines: `CI_MERGE_REQUEST_SOURCE_BRANCH_SHA`
+- Azure Pipelines: `SYSTEM_PULLREQUEST_SOURCECOMMITID`
+- Travis CI: `TRAVIS_PULL_REQUEST_SHA`
+- Semaphore: `SEMAPHORE_GIT_PR_SHA`
+- Buildkite: `BUILDKITE_PULL_REQUEST_HEAD_COMMIT`
+- Bitbucket Pipelines: `BITBUCKET_COMMIT`
+
+The commit is used only when the checked-out commit is a merge and the commit is one of its parents. If a shallow clone does not contain it (for example `actions/checkout` with the default `fetch-depth: 1`), it is fetched with `git fetch --depth=1 origin <sha>`, with a 3 second timeout. If the fetch fails, the checked-out commit is reported. Set `CURRENTS_DISABLE_HEAD_COMMIT_FETCH=true` to skip the fetch.
+
+The `COMMIT_INFO_*` variables below still take priority. When `COMMIT_INFO_SHA` is set, the pull request's commit is not looked up.
+
 ## Fallback environment variables
 
 If getting the commit information using `git` fails for some reason, you can provide the commit information by setting the environment variables. This module will look at the following environment variables as a fallback

package.json

@@ -1,7 +1,7 @@
 {
   "name": "@currents/commit-info",
   "description": "Collects Git commit info from CI or from CLI",
-  "version": "1.0.1-beta.0",
+  "version": "1.1.0-beta.0",
   "author": "Gleb Bahmutov <gleb.bahmutov@gmail.com>",
   "contributors": [
     "Gleb Bahmutov <gleb.bahmutov@gmail.com>",
@@ -28,7 +28,7 @@
     }
   },
   "engines": {
-    "node": ">=6"
+    "node": ">=8"
   },
   "files": [
     "src/*.js",

src/index.js

@@ -16,6 +16,7 @@ const {
   getCommitInfoFromEnvironment,
   getGhaEventData
 } = require('./utils')
+const { getPullRequestHeadCommit } = require('./pull-request-head')
 const Promise = require('bluebird')
 const { mergeWith, or } = require('ramda')
 
@@ -35,12 +36,22 @@ function commitInfo (folder) {
       process.env.GITHUB_EVENT_PATH,
       process.env.GITHUB_ACTIONS
     )
-  }).then(info => {
-    const envVariables = getCommitInfoFromEnvironment()
-    debug('git commit: %o', info)
-    debug('env commit: %o', envVariables)
-    return mergeWith(or, envVariables, info)
   })
+    .then(info => {
+      // COMMIT_INFO_SHA names the commit to report, so it is used as is
+      if (process.env.COMMIT_INFO_SHA) {
+        return info
+      }
+      return getPullRequestHeadCommit(folder, info.sha, info.ghaEventData).then(
+        head => Object.assign({}, info, head)
+      )
+    })
+    .then(info => {
+      const envVariables = getCommitInfoFromEnvironment()
+      debug('git commit: %o', info)
+      debug('env commit: %o', envVariables)
+      return mergeWith(or, envVariables, info)
+    })
 }
 
 module.exports = {