Are dreams visions of the future?

No, dreams aren't supposed to be viewed as visions of the future.
When one dreams they are undergoing a mental process that distributes images, that relate to real life, fears, hopes, and emotional values. The images have symbolical meaning, but most often do not indicate a vision of the future. However, the brain can be aware of what will happen as a result of what it is you are doing in life, this can be played out in dreams, and thought of as a vision.