Eloquent Bug between Repository & Testing

Hey guys,

Not sure how to solve this issue at the moment, exhausted google and team members.

The following code produces the correct result when called from a Controller... perfect, no issues whatsoever.

public function categoryMonthlyBookings(Request $request = null, $status = null)
    {
        $query = Booking::join('categories', 'categories.id', '=', 'bookings.category_id');

        if (!is_null($status)) {
            $query->where('status', $status);
        }

        $query = $query->select('date', 'categories.display_name', 'categories.id AS category_id', DB::raw('count(*) as count, SUM(total) as total'))
        ->orderBy('date')
        // ->raw('GROUP BY(MONTH(date))')
        ->groupBy(DB::raw('MONTH(date)'))
        ->groupBy('category_id')
        ->get()->groupBy(function ($booking) {
            return Carbon::parse($booking->date)->format('m/Y'); // grouping by months
        });

        return $query;
    }

However when it is run via a test in the command line, it returns with:

) RepositoryTest::it_returns_all_bookings_count_and_sum_by_month_year_and_category
Illuminate\Database\QueryException: SQLSTATE[HY000]: General error: 1 no such function: month (SQL: select "date", "categories"."display_name", "categories"."id" as "category_id", count(*) as count, SUM(total) as total from "bookings" inner join "categories" on "categories"."id" = "bookings"."category_id" where "bookings"."deleted_at" is null group by month(date), "category_id" order by "date" asc)

Caused by
PDOException: SQLSTATE[HY000]: General error: 1 no such function: month

If I swap it out with that commented line using ->raw() it works in the controller & test but does not produce the right results. I'm at a loss on this one, not sure why the ->groupBy(DB::raw('MONTH(date)')) does not work in the testing environment.

All help is appreciated