Implementation of the URL website for recruitment interview purposes

url_service.py

#!/usr/bin/env python
"""Server site implementation of the product, where users can
    save URLs and retrieve them later."""

__author__ = "Wiktor Reczek"


class UrlService:
    """CRUD service without `update`."""

    def __init__(self):
        # We use dictionary here as we can get any user in O(1) time (in average case).
        self.users_urls = {}

    def saveUrl(self, userToken, URL):
        """Saves the URL to the specified user's collection.

        Args:
            userToken (str): user unique ID.
            URL (str): uniform resource locator to save.

        Returns:
            bool: True, if new URL was saved, otherwise False.
        """
        if userToken not in self.users_urls:
            # We use the set here as we don't need to have our data to be ordered sequence.
            self.users_urls[userToken] = set()

        if URL in self.users_urls[userToken]:
            return False

        self.users_urls[userToken].add(URL)
        return True

    def getUrls(self, userToken):
        """Reads all saved URLs of given user.

        Args:
            userToken (str): unique user ID.

        Returns:
            set: all URLs that user have saved. Returns empty set
                if no URLs have been stored for the user.
        """
        if userToken not in self.users_urls:
            return set()

        return self.users_urls[userToken]

    def removeUrl(self, userToken, URL):
        """Deletes given URL from the specified user's collection.

        Args:
            userToken (str): unique user ID.
            URL (str): uniform resource locator to delete.

        Returns:
            bool: whether or not the URL was deleted. Returns False
                if the URL to be deleted had never been saved for given user.
        """
        if userToken not in self.users_urls:
            raise KeyError(f"\tUser token {userToken} does not exist.")

        try:
            self.users_urls[userToken].remove(URL)
            return True
        except KeyError:
            print(f"\tKey '{URL}' not found")
            return False


def test_adding_and_removing_for_one_user():
    print("### TEST CASE NO 1 ###")
    service = UrlService()

    service.saveUrl("tom", "www.example.com")
    service.saveUrl("tom", "www.example.com/news")
    service.saveUrl("john", "www.other.com")

    found = len(service.getUrls("tom"))
    if found != 2:
        print(f"Something went wrong. "
              f"There should be 2 URLs assigned to tom but {found} found")

    service.removeUrl("john", "www.other.com")

    print(f"\ttom's urls: {service.getUrls('tom')}")
    print(f"\tjohn's urls: {service.getUrls('john')}")

    print("### ############## ###\n")

def test_adding_and_removing_for_many_users():
    print("### TEST CASE NO 2 ###")

    service = UrlService()

    service.saveUrl("victor", "https://www.montrosesoftware.com/#/")
    service.saveUrl("victor", "https://www.google.com")
    service.saveUrl("victor", "https://www.stackoverflow.com")

    service.removeUrl("victor", "https://www.stackoverflow.com")
    service.removeUrl("victor", "https://www.doesnotexist.com")
    print(f"\tvictor's urls: {service.getUrls('victor')}")

    service.saveUrl("paul", "https://www.montrosesoftware.com/contact.html#/")
    print(f"\tpaul's urls: {service.getUrls('paul')}")

    service.saveUrl("maria", "https://www.montrosesoftware.com/about.html#/")
    print(f"\tmaria's's urls: {service.getUrls('maria')}")

    assert service.getUrls("victor") == {'https://www.montrosesoftware.com/#/', 'https://www.google.com'}
    assert service.getUrls("paul") == {'https://www.montrosesoftware.com/contact.html#/'}
    assert service.getUrls("maria") == {'https://www.montrosesoftware.com/about.html#/'}

    print("### ############## ###\n")

def test_add_methods():
    print("### TEST CASE NO 3 ###")

    service = UrlService()

    firstSave = service.saveUrl("christopher", "https://www.somesite.com")
    secondSave = service.saveUrl("christopher", "https://www.somesite.com")

    assert firstSave == True, "Should be True as this site was saved for the first time for this user."
    assert secondSave == False, "Should be False as this site was saved twice."

    gotUrls = service.getUrls("unauthorized")

    assert gotUrls == set(), "Should return empty list as this user haven't saved any URL yet."

    print("### ############## ###\n")

def test_getting_from_not_registered_user():
    print("### TEST CASE NO 4 ###")

    service = UrlService()

    gotUrls = service.getUrls("unauthorized")

    assert gotUrls == set(), "Should return empty list as this user haven't saved any URL yet."

    print("### ############## ###\n")


def test_removing_for_not_registered_user():
    print("### TEST CASE NO 5 ###")

    service = UrlService()
    try:
        service.removeUrl("victor", "https://www.youtube.com")
    except Exception:
        print("\tCaught exception as user haven't specified any URL yet.")

    print("### ############## ###\n")


def test_removing_not_saved_url():
    print("### TEST CASE NO 6 ###")

    service = UrlService()

    service.saveUrl("peter", "some_url")

    removed = service.removeUrl("peter", "some_other_url")

    assert removed == False, "\tShould be False as this user haven't specified this url."

    print("### ############## ###\n")


if __name__ == '__main__':
    test_adding_and_removing_for_one_user()
    test_adding_and_removing_for_many_users()
    test_add_methods()
    test_getting_from_not_registered_user()
    test_removing_for_not_registered_user()
    test_removing_not_saved_url()