Hypothesis generates large number of invalid examples

test_high_failures.py

from datetime import datetime, time

import pytest
from hypothesis import given, assume, strategies as st
from hypothesis import settings, Verbosity

_cities = [f"city{i}" for i in range(4)]

_dt = st.shared(
    st.datetimes(
        min_value=datetime(2019, 1, 1), max_value=datetime(2029, 12, 31)
    )
)

# working hours
utc = time(2, 30), time(2 + 12, 30)


@st.composite
def datestr(draw, dt):
    return (
        draw(dt)
        .replace(hour=0, minute=0, second=0, microsecond=0)
        .isoformat(timespec="milliseconds")
        + "Z"
    )


@st.composite
def timestamp(draw, dt, working_hrs):
    ts = draw(dt)
    if working_hrs:
        t1, t2 = working_hrs
        assume(t1 <= ts.time() <= t2)
    return ts.isoformat(timespec="milliseconds") + "Z"


def get_req(dt, cities, hrs):
    return st.fixed_dictionaries(
        {
            "date": datestr(dt),
            "city": st.sampled_from(cities),
            "slots": st.lists(timestamp(dt, hrs), min_size=1, max_size=5),
        }
    )


api_request = st.lists(get_req(_dt, _cities, hrs=utc), min_size=1, max_size=5)


@settings(max_examples=100, verbosity=Verbosity.verbose)
@given(api_request)
def test_api_gen(reqs):
    assert len(reqs) > 0


def get_req_only_ts(dt, hrs):
    return st.fixed_dictionaries(
        {
            "date": datestr(dt),
            "slots": st.lists(timestamp(dt, hrs), min_size=1, max_size=5),
        }
    )


api_request_no_city = st.lists(
    get_req_only_ts(_dt, hrs=utc), min_size=1, max_size=5
)


@settings(max_examples=100, verbosity=Verbosity.verbose)
@given(api_request_no_city)
def test_api_gen_no_city(reqs):
    assert len(reqs) > 0


api_request_all_day = st.lists(
    get_req(_dt, _cities, hrs=None), min_size=1, max_size=5
)


@settings(max_examples=100, verbosity=Verbosity.verbose)
@given(api_request_all_day)
def test_api_gen_all_day(reqs):
    assert len(reqs) > 0