How can i write UnitTest for my Flask API

I'm fairly new to unit testing, and im required to write some unit test for my flask api. Any idea how I can write unit tests for this code below? Any examples and help will be appreciated. I tried to create a seperate file to start unittesting but im not able to import the flask app into the file as it gives me module errors. And ontop of that im not sure how to test each function in this application.

from flask import Flask, request, Response, send_file
import machine_learning_model.Object_detection.yoloModel as yoloModel
import jsonpickle
import numpy as np
import cv2
import base64
import json
import ast
import requests
app = Flask(__name__)


url_base = 'http://192.168.1.6:5000'
predict_image_api = '/v1/api/predict'
bounding_box_API = '/v1/resoures/predict_images/'


# Load YOLO model
labels, colors = yoloModel.load_label("coco.names")
net, ln = yoloModel.load_model()


# route http posts to this method
@app.route(predict_image_api, methods=['GET', 'POST'])
def predict():
    loaded_body = parse_json_from_request(request)
    
    # Conversion of base64 image back to its binary
    img_original = base64.b64decode(loaded_body['image'])

    # Conversion of image data to unit8
    jpg_as_np = np.frombuffer(img_original, dtype=np.uint8)
    
    # Decoding the image
    image = cv2.imdecode(jpg_as_np, cv2.IMREAD_COLOR)

    idxs, boxes, confiences, centers, classIDs = yoloModel.detectObjectFromImage(image, net, ln)

    objectProperty = yoloModel.bouding_box(idxs, image, boxes, colors, labels, classIDs, confiences)

    response = {
        'objectProperty':''
    }
    response['objectProperty'] = objectProperty
    print(response)
    # encode response using jsonpickle
    response_pickled = jsonpickle.encode(response)



    return Response(response=response_pickled, status=200, mimetype="application/json")

@app.route(bounding_box_API+'<name>', methods=['GET'])
def get_image(name):
    filename = 'predict_images/output_resize_%s.jpg' % name
    print(filename)
    return send_file(filename, mimetype='image/gif')


def parse_json_from_request(request):
    body_dict = request.json
    body_str = json.dumps(body_dict)
    loaded_body = ast.literal_eval(body_str)
    return loaded_body

if __name__ == "__main__":
    # start flask app
    app.run()

First of all, I recommend to use pytest.

In order to be correcly unit-tested, your program should be split into simple functions that preferably perform only 1 task.

Since you are working with requests, you may want to test your HTTP calls. A good way to test them is to use responses in order to mock the target server or API.

Pragmatically, start to create a folder tests/ and create a file per class or per function, named after the class or the function you want to test (like so test_your_function.py). Inside this file, write unit tests for your functions (i.e. a function that starts by test_ so that pytest will identify it as a unit test). Each unit test should contain an assert tested_output_value == expected_output_value statement, so that your unit test fails if your function does not return the desired tested_output_value.

For instance, if you want to test your function predict one way to do it would be write a function that requests your localhost server and to verify that the response is what you expected. N.B.: Before running pytest, make sure that you have started your server ;)