fix(commits): add helpful error when lastRelease not in history

Closes #61, Closes #50

src/lib/commits.js

@@ -1,25 +1,64 @@
 const { exec } = require('child_process')
 
-module.exports = function ({lastRelease}, cb) {
+const log = require('npmlog')
+
+const SemanticReleaseError = require('@semantic-release/error')
+
+module.exports = function ({lastRelease, branch}, cb) {
   const from = lastRelease.gitHead
   const range = (from ? from + '..' : '') + 'HEAD'
 
-  exec(
-    `git log -E --format=%H==SPLIT==%B==END== ${range}`,
-    (err, stdout) => {
-      if (err) return cb(err)
+  if (!from) return extract()
 
-      cb(null, String(stdout).split('==END==\n')
+  exec(`git branch --contains ${from}`, (err, stdout) => {
+    if (err) return cb(err)
+    let inHistory = false
 
-      .filter((raw) => !!raw.trim())
+    const branches = stdout.split('\n')
+    .map((result) => {
+      if (branch === result.replace('*', '').trim()) {
+        inHistory = true
+        return null
+      }
+      return result.trim()
+    })
+    .filter(branch => !!branch)
 
-      .map((raw) => {
-        const data = raw.split('==SPLIT==')
-        return {
-          hash: data[0],
-          message: data[1]
-        }
-      }))
+    if (!inHistory) {
+      log.error('commits',
+`The commit the last release of this package was derived from is no longer
+in the direct history of the "${branch}" branch.
+This means semantic-release can not extract the commits between now and then.
+This is usually caused by force pushing or releasing from an unrelated branch.
+You can recover from this error by publishing manually or restoring
+the commit "${from}".` + (branches.length ?
+        `\nHere is a list of branches that still contain the commit in question: \n * ${branches.join('\n * ')}` :
+        ''
+      ))
+      return cb(new SemanticReleaseError('Commit not in history', 'ENOTINHISTORY'))
     }
-  )
+
+    extract()
+  })
+
+  function extract () {
+    exec(
+      `git log -E --format=%H==SPLIT==%B==END== ${range}`,
+      (err, stdout) => {
+        if (err) return cb(err)
+
+        cb(null, String(stdout).split('==END==\n')
+
+        .filter((raw) => !!raw.trim())
+
+        .map((raw) => {
+          const data = raw.split('==SPLIT==')
+          return {
+            hash: data[0],
+            message: data[1]
+          }
+        }))
+      }
+    )
+  }
 }