Sending JSON File as Post Request Flask

I'm writing a test to retrieve the top n posts from a community.

Before getting those values, I want to post data from a JSON file, instead of posting them to the endpoint individually.

I've tried slight variations of test_retrieve_recent_posts_existing_community, but keep getting a TypeError.

Can anyone suggest how I can fix the test case?

Route:

@app.route('/api/v2/post/retrieve/<community>/<top>', methods=['GET'])
def recent_community_posts(community=None, top=0):
    community = request.args.get('community')
    top       = request.args.get('top')
    filtered_posts = []
    if community:
        for post in posts:
            if post['community'] == community:
                filtered_posts.append(post)
    
    if len(filtered_posts) == 0:
        return {'message': 'Community does not exist ...', 'status': 402}
    return {'data': jsonify(filtered_posts[:top]), 'message': "Filtered data based on community", 'status': 203} 

Test:

def test_retrieve_recent_posts_existing_community(client):
    with open('posts.json') as posts_data:
        posts_json = json.dumps(posts_data)

    client.post('/api/v2/post/create', data=json.dump(posts_json), content_type='application/json')

    response = client.get('/api/v2/post/retrieve/tech/2')
    data = json.load(response.get_data(as_text=True))
    assert "Filtered data" in data["message"] and data["status"] == 203

Error:

TypeError: Object of type TextIOWrapper is not JSON serializable

File (posts.json):

[
    {
        "postid": 2,
        "title": "Heading 2",
        "text": "Content of post 2",
        "published": "YYYY/MM/DD hh:mm:ss",
        "community": "tech"
    },
    {
        "postid": 3,
        "title": "Heading 3",
        "text": "Content of post 3",
        "published": "YYYY/MM/DD hh:mm:ss",
        "community": "tech"
    },
    {
        "postid": 4,
        "title": "Heading 4",
        "text": "Content of post 4",
        "published": "YYYY/MM/DD hh:mm:ss",
        "community": "art"
    },
    {
        "postid": 5,
        "title": "Heading 5",
        "text": "Content of post 5",
        "published": "YYYY/MM/DD hh:mm:ss",
        "community": "art"
    },
    {
        "postid": 6,
        "title": "Heading 6",
        "text": "Content of post 6",
        "published": "YYYY/MM/DD hh:mm:ss",
        "community": "science"
    },
    {
        "postid": 7,
        "title": "Heading 7",
        "text": "Content of post 7",
        "published": "YYYY/MM/DD hh:mm:ss",
        "community": "tech"
    }
]