Create a warning notification when trying to run forward propagation on a neural network without test data

[AyaMoussa]

Is your feature request related to a problem? Please describe.

• When trying to run forward propagation (neuron by neuron, layer by layer or the whole network) on a neural network without providing test data, no change happens. User may not know why it is not working.

Describe the solution you'd like

• To create a more user friendly interface, I suggest creating a pop-up notification to warn the user about the lack of test data