Allow for Dynamic Options

[viktor-rick]

Is your feature request related to a problem? Please describe.
Many apps use callback functions. They should be tested for.

Describe the solution you'd like
At the very least automatically convert the callback functions into strategies.

Dev notes
This is a complex thing as hypothesis doesn't easily allow for this. The Parametrization is parsed to strategies, and Hypothesis picks from this. Therefore, the callback function can't be ran as we don't know the filled in value (only the strategy on how to pick).

Optionally we'd test the callback functions as views seperately (similar to Controller views), and in the process create a mapping. After draw(strategy) is ran, we fill in the fields with Dynamic Options

[viktor-rick]

https://hypothesis.readthedocs.io/en/latest/reference/strategies.html#hypothesis.strategies.SearchStrategy.flatmap

[viktor-rick]

from hypothesis.strategies._internal.core import deferred

# Define the strategies for the options of A
a_options = st.sampled_from(['A', 'B', 'C'])

# Assume b_strategy is a function that returns a list of options based on the value of A
def b_strategy(a):
    if a == 'A':
        return ['A1', 'A2', 'A3']
    elif a == 'B':
        return ['B1', 'B2', 'B3']
    else:
        return []

# Helper function to create the full strategy based on a drawn value of 'a'
def create_dependent_strategy(d):
    a_value = d['a']
    b_options = b_strategy(a_value)
    
    # If b_strategy returns empty list, use None; otherwise sample from the list
    if not b_options:
        b_strategy_to_use = st.none()
    else:
        b_strategy_to_use = st.sampled_from(b_options)
    
    return st.fixed_dictionaries({
        'a': st.just(a_value),
        'b': b_strategy_to_use
    })

# Create a combined strategy where 'b' depends on the drawn value of 'a'
combined_strategy = st.fixed_dictionaries({'a': a_options}).flatmap(create_dependent_strategy)

@given(combined_strategy)
def test_example(params):
    a = params['a']
    b = params['b']
    if a == 'A':
        assert b in ['A1', 'A2', 'A3']
    elif a == 'B':
        assert b in ['B1', 'B2', 'B3']
    else:
        assert b is None  # b should be None when a is 'C'

if __name__ == "__main__":
    # Run the test
    test_example()```