Ghostwriter does not always identify required imports

[strue36]

Given the following file example.py

from dataclasses import dataclass
from typing import List


@dataclass
class NestedExample:
    name: str


@dataclass
class Example:
    list_example: List[NestedExample]

The output of hypothesis write is

# This test code was written by the `hypothesis.extra.ghostwriter` module
# and is provided under the Creative Commons Zero public domain dedication.

import example
from hypothesis import given, strategies as st


@given(list_example=st.lists(st.builds(NestedExample)))
def test_fuzz_Example(list_example):
    example.Example(list_example=list_example)


@given(name=st.text())
def test_fuzz_NestedExample(name):
    example.NestedExample(name=name)


@given(
    cls=st.none(),
    init=st.booleans(),
    repr=st.booleans(),
    eq=st.booleans(),
    order=st.booleans(),
    unsafe_hash=st.booleans(),
    frozen=st.booleans(),
)
def test_fuzz_dataclass(cls, init, repr, eq, order, unsafe_hash, frozen):
    example.dataclass(
        cls,
        init=init,
        repr=repr,
        eq=eq,
        order=order,
        unsafe_hash=unsafe_hash,
        frozen=frozen,
    )

This is missing an import for NestedExample

It appears that within _imports_for_strategy() we need to check for strategy being a ListStrategy, and in that case call _imports_for_strategy(strategy.element_strategy).

There is a complication in that TextStrategy also inherits from ListStrategy. On my own branch I currently check for the following

# get the underlying strategy for elements of a list
if isinstance(strategy, ListStrategy) and not isinstance(strategy, TextStrategy):
    imports |= _imports_for_strategy(strategy.element_strategy)

but am open to suggestions as to the best way to handle this.

[Zac-HD]

Thanks for the report @strue36! I think your fix looks good here, though we can simplify it further - it's fine to add the imports for the elements of a TextStrategy, and simpler code is worth the (too-small-to-measure) perf hit here I think.

If you'd like to open a PR for this, I'd be delighted to accept it - just remember to add the RELEASE.rst and your name to the list in AUTHORS.rst 😁