Add support for polling Travis CI builds by SHA.

Compared to the nodejs.org repo, Travis doesn't pick up newly created PR's
from nodejs/readable-stream. Strangely enough it does pick up commits and
builds them though.

Therefore these changes adds support for polling Travis builds by commit SHAs
rather than PR #id alone. The bot tries to do a smart choice about which polling
to use by checking if Travis has had *any* builds triggered by PR's lately,
if not if starts to poll by SHA.

Author: phillipj

lib/pollTravis.js

@@ -22,7 +22,33 @@ githubClient.authenticate({
   token: process.env.GITHUB_TOKEN
 })
 
-function pollAndComment (owner, repoName, prId, checkNumber) {
+function pollThenComment (owner, repoName, prId) {
+  const prInfo = prInfoStr({ owner, repoName, prId })
+
+  // we have to figure out what type of Travis polling we should perform,
+  // either by PR #id (as for nodejs.org) or commit sha (for readable-stream)
+  travisClient.repos(owner, repoName).builds.get((err, res) => {
+    if (err) {
+      return console.error(`! ${prInfo} Error while retrieving initial builds`, err.stack)
+    }
+
+    const hasAnyPrBuilds = res.builds.some((build) => build.pull_request)
+
+    if (hasAnyPrBuilds) {
+      pollByPrThenComment(owner, repoName, prId)
+    } else {
+      pollByCommitThenComment(owner, repoName, prId)
+    }
+  })
+}
+
+/**
+ * When Travis CI picks up our PR's, we can poll and match builds
+ * by their related PR #id.
+ *
+ * That's the case for nodejs.org.
+ */
+function pollByPrThenComment (owner, repoName, prId, checkNumber) {
   checkNumber = checkNumber || 1
 
   const prInfo = prInfoStr({ owner, repoName, prId })
@@ -56,7 +82,75 @@ function pollAndComment (owner, repoName, prId, checkNumber) {
       console.warn(`! ${prInfo} Was not able to find matching build, will do check #${checkNumber + 1} in 30 seconds`)
     }
 
-    setTimeout(pollAndComment, 30 * 1000, owner, repoName, prId, checkNumber + 1)
+    setTimeout(pollByPrThenComment, 30 * 1000, owner, repoName, prId, checkNumber + 1)
+  })
+}
+
+/**
+ * When Travis CI *doesn't* pick up our PR's, we have to poll and match builds
+ * by the last commit SHA of the related PR.
+ *
+ * This is the case for readable-stream.
+ */
+function pollByCommitThenComment (owner, repoName, prId) {
+  const prInfo = prInfoStr({ owner, repoName, prId })
+
+  githubClient.pullRequests.getCommits({
+    user: owner,
+    repo: repoName,
+    number: prId
+  }, (err, commitMetas) => {
+    if (err) {
+      return console.error(`! ${prInfo} Got error when retrieving GitHub commits for PR`, err.stack)
+    }
+
+    const lastSha = commitMetas.pop().sha
+    pollTravisBuildBySha({ owner, repoName, prId, lastSha })
+    console.log(`* ${prInfo} Started polling Travis for build by commit ${lastSha.substr(0, 7)}`)
+  })
+}
+
+function pollTravisBuildBySha (options, checkNumber) {
+  const createGhComment = createGhCommentFn(options)
+  const prInfo = prInfoStr(options)
+  const shaToMatch = options.lastSha
+
+  checkNumber = checkNumber || 1
+
+  if (checkNumber > 100) {
+    console.warn(`* ${prInfo} Was not able to find matching build for PR, stopping poll now :(`)
+    return
+  }
+
+  travisClient.repos(options.owner, options.repoName).builds.get((err, res) => {
+    if (err) {
+      return console.error(`! ${prInfo} Got error when retrieving Travis builds`, err.stack)
+    }
+
+    const matchingCommit = res.commits.find((commit) => commit.sha === shaToMatch)
+    if (!matchingCommit) {
+      console.warn(`! ${prInfo} Travis hasn't picked up last commit yet, will do check #${checkNumber + 1} in 30 seconds`)
+      return setTimeout(pollTravisBuildBySha, 30 * 1000, options, checkNumber + 1)
+    }
+
+    const lastBuildForCommit = res.builds.find((build) => build.commit_id === matchingCommit.id)
+    if (lastBuildForCommit) {
+      const lastState = lastBuildForCommit.state
+
+      if (lastState === 'passed') {
+        return createGhComment(`[Travis build passed](https://travis-ci.org/${options.owner}/${options.repoName}/builds/${lastBuildForCommit.id}) :+1:`)
+      } else if (lastState === 'failed') {
+        return createGhComment(`[Travis build failed](https://travis-ci.org/${options.owner}/${options.repoName}/builds/${lastBuildForCommit.id}) :-1:`)
+      } else if (~['created', 'started'].indexOf(lastState)) {
+        console.log(`* ${prInfo} "${lastState}" build found, will do check #${checkNumber + 1} in 30 seconds`)
+      } else {
+        return console.log(`* ${prInfo} Unknown build state: "${lastState}", stopping polling`)
+      }
+    } else {
+      console.warn(`! ${prInfo} Was not able to find matching build by last commit, will do check #${checkNumber + 1} in 30 seconds`)
+    }
+
+    setTimeout(pollTravisBuildBySha, 30 * 1000, options, checkNumber + 1)
   })
 }
 
@@ -71,7 +165,7 @@ function createGhCommentFn (options) {
       body: message
     }, (err, res) => {
       if (err) {
-        return console.error(`! ${prInfo} Error from GitHub`, err.stack)
+        return console.error(`! ${prInfo} Error while creating GitHub comment`, err.stack)
       }
       console.log(`* ${prInfo} Github comment created`)
     })
@@ -82,4 +176,4 @@ function prInfoStr (options) {
   return `${options.owner}/${options.repoName}/#${options.prId}`
 }
 
-exports.pollAndComment = pollAndComment
+exports.pollThenComment = pollThenComment

server.js

@@ -16,15 +16,15 @@ app.all('/hooks/github', (req, res) => {
     const repo = req.body.repository
 
     console.log(`* ${repo.owner.login}/${repo.name}/#${req.body.number} Opened, starting build checks!`)
-    pollTravis.pollAndComment(repo.owner.login, repo.name, parseInt(req.body.number))
+    pollTravis.pollThenComment(repo.owner.login, repo.name, parseInt(req.body.number))
   }
 
   res.end()
 })
 
 // to trigger polling manually
 app.get('/pr/:owner/:repo/:prId', (req, res) => {
-  pollTravis.pollAndComment(req.params.owner, req.params.repo, parseInt(req.params.prId))
+  pollTravis.pollThenComment(req.params.owner, req.params.repo, parseInt(req.params.prId))
   res.end()
 })