Test methods fail using Storage. Illuminate\Http\Testing\imagepng() in Laravel

Whatever is executing your tests needs to have the PHP GD extension

I recently ran into this problem and installed PHP GD Extension

Here's the code I placed in my Dockerfile

RUN apt-get update && \
    apt-get install -y \
    libzip-dev \
    libjpeg62-turbo-dev \
    libpng-dev

RUN docker-php-ext-install gd

Note: Installing gd requires that you have libzip, libpng e.t.c