src/GitWorkingCopy.php
public function isUpToDate(): bool
    {
        if (! $this->isTracking()) {
            throw new GitException(
                'Error: HEAD does not have a remote tracking branch. Cannot check if it is up-to-date.'
            );
        }

        $mergeBase = $this->run('merge-base', ['@', '@{u}']);
        $remoteSha = $this->run('rev-parse', ['@{u}']);
        return $mergeBase === $remoteSha;
    }
public function isUpToDate(): bool
    {
        if (! $this->isTracking()) {
            throw new GitException(
                'Error: HEAD does not have a remote tracking branch. Cannot check if it is up-to-date.'
            );
        }

        $mergeBase = $this->run('merge-base', ['@', '@{u}']);
        $remoteSha = $this->run('rev-parse', ['@{u}']);
        return $mergeBase === $remoteSha;
    }
Returns whether HEAD is up-to-date with its remote tracking branch.