pytest-flask streaming

app.py

from flask import Flask

import streamer

def create_app():
    app = Flask(__name__)

    app.register_blueprint(streamer.mod)

    return app

conftest.py

from app import create_app

import pytest

@pytest.fixture(scope='session')
def app():
    return create_app()


@pytest.yield_fixture
def client(app):
    with app.test_client() as client:
        yield client

streamer.py

import json

from flask import Blueprint
from flask import Response
from flask import stream_with_context

mod = Blueprint('streamer', __name__)

@mod.route('/stream')
def stream():
    gimme_data = generate_data(10)

    json_data = (
        json.dumps(each) + '\n'
        for each in gimme_data
    )

    return Response(
        stream_with_context(json_data),
        mimetype='application/x-json-stream',
    )


def generate_data(length):
    for i in range(length):
        yield {
            'id': i,
        }

test.py

import json

from flask import url_for

def test_something(client):
    resp = client.get(
        url_for('streamer.stream'),
    )

    assert resp.status_code == 200

    data = [
        json.loads(each)
        for each in resp.data.decode().split('\n')
        if each
    ]

    assert len(data) == 10