From a8747c4f86a1947250aa86ab1869fb4bde10bb71 Mon Sep 17 00:00:00 2001
From: Pierre Vanduynslager <pierre.denis.vanduynslager@gmail.com>
Date: Tue, 10 Dec 2019 00:06:26 -0500
Subject: [PATCH] fix: verify is branch is up to date by comparing remote and
 local HEAD

---
 lib/git.js       | 38 ++++----------------------------------
 test/git.test.js | 31 ++++++++-----------------------
 2 files changed, 12 insertions(+), 57 deletions(-)

diff --git a/lib/git.js b/lib/git.js
index 563b477424..dc75018ac3 100644
--- a/lib/git.js
+++ b/lib/git.js
@@ -69,33 +69,6 @@ async function getBranches(repositoryUrl, execaOpts) {
     .filter(Boolean);
 }
 
-/**
- * Verify if the `ref` is in the direct history of a given branch.
- *
- * @param {String} ref The reference to look for.
- * @param {String} branch The branch for which to check if the `ref` is in history.
- * @param {Object} [execaOpts] Options to pass to `execa`.
- *
- * @return {Boolean} `true` if the reference is in the history of the current branch, falsy otherwise.
- */
-async function isRefInHistory(ref, branch, execaOpts) {
-  if (!(await isRefExists(branch, execaOpts))) {
-    return false;
-  }
-
-  try {
-    await execa('git', ['merge-base', '--is-ancestor', ref, branch], execaOpts);
-    return true;
-  } catch (error) {
-    if (error.exitCode === 1) {
-      return false;
-    }
-
-    debug(error);
-    throw error;
-  }
-}
-
 /**
  * Verify if the `ref` exits
  *
@@ -310,12 +283,10 @@ async function verifyBranchName(branch, execaOpts) {
  * @return {Boolean} `true` is the HEAD of the current local branch is the same as the HEAD of the remote branch, falsy otherwise.
  */
 async function isBranchUpToDate(repositoryUrl, branch, execaOpts) {
-  const {stdout: remoteHead} = await execa('git', ['ls-remote', '--heads', repositoryUrl, branch], execaOpts);
-  try {
-    return await isRefInHistory(remoteHead.match(/^(?<ref>\w+)?/)[1], branch, execaOpts);
-  } catch (error) {
-    debug(error);
-  }
+  return (
+    (await getGitHead(execaOpts)) ===
+    (await execa('git', ['ls-remote', '--heads', repositoryUrl, branch], execaOpts)).stdout.match(/^(?<ref>\w+)?/)[1]
+  );
 }
 
 /**
@@ -355,7 +326,6 @@ module.exports = {
   getTags,
   getCommits,
   getBranches,
-  isRefInHistory,
   isRefExists,
   fetch,
   fetchNotes,
diff --git a/test/git.test.js b/test/git.test.js
index 09c2180262..781994f65b 100644
--- a/test/git.test.js
+++ b/test/git.test.js
@@ -2,7 +2,6 @@ import test from 'ava';
 import tempy from 'tempy';
 import {
   getTagHead,
-  isRefInHistory,
   isRefExists,
   fetch,
   getGitHead,
@@ -125,23 +124,6 @@ test('Fetch all tags on a repository with a detached head from branch', async t
   t.deepEqual((await getTags('master', {cwd})).sort(), ['v1.0.0', 'v1.0.1', 'v1.1.0', 'v2.0.0'].sort());
 });
 
-test('Verify if the commit `sha` is in the direct history of the current branch', async t => {
-  // Create a git repository, set the current working directory at the root of the repo
-  const {cwd} = await gitRepo();
-  // Add commits to the master branch
-  const commits = await gitCommits(['First'], {cwd});
-  // Create the new branch 'other-branch' from master
-  await gitCheckout('other-branch', true, {cwd});
-  // Add commits to the 'other-branch' branch
-  const otherCommits = await gitCommits(['Second'], {cwd});
-  await gitCheckout('master', false, {cwd});
-
-  t.true(await isRefInHistory(commits[0].hash, 'master', {cwd}));
-  t.falsy(await isRefInHistory(otherCommits[0].hash, 'master', {cwd}));
-  t.falsy(await isRefInHistory(otherCommits[0].hash, 'missing-branch', {cwd}));
-  await t.throwsAsync(isRefInHistory('non-existant-sha', 'master', {cwd}));
-});
-
 test('Verify if a branch exists', async t => {
   // Create a git repository, set the current working directory at the root of the repo
   const {cwd} = await gitRepo();
@@ -299,13 +281,16 @@ test('Return falsy if repository is not up to date', async t => {
   t.falsy(await isBranchUpToDate(repositoryUrl, 'master', {cwd}));
 });
 
-test('Return "true" if local repository is ahead', async t => {
-  const {cwd, repositoryUrl} = await gitRepo(true);
-  await gitCommits(['First'], {cwd});
-  await gitPush(repositoryUrl, 'master', {cwd});
+test('Return falsy if detached head repository is not up to date', async t => {
+  let {cwd, repositoryUrl} = await gitRepo();
+
+  const [commit] = await gitCommits(['First'], {cwd});
   await gitCommits(['Second'], {cwd});
+  await gitPush(repositoryUrl, 'master', {cwd});
+  cwd = await gitDetachedHead(repositoryUrl, commit.hash);
+  await fetch(repositoryUrl, 'master', 'master', {cwd});
 
-  t.true(await isBranchUpToDate(repositoryUrl, 'master', {cwd}));
+  t.falsy(await isBranchUpToDate(repositoryUrl, 'master', {cwd}));
 });
 
 test('Get a commit note', async t => {