inital docs

.gitignore

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+*.venv
+*__pycache__*

solution/Makefile

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+test:
+	poetry run pytest
+
+coverage:
+	poetry run pytest --cov=src tests/
+
+format:
+	poetry run black .

solution/README.md

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+# DI US Shopping - Checkout System
+
+## Prerequisites
+- Install [Python](https://www.python.org/downloads/) (make sure you install a version that is compatible with this project, this can be found in the [pyproject file](pyproject.toml))
+- Install [Poetry](https://python-poetry.org/docs/) to manage your virtual environment.
+- Install [Make](https://www.gnu.org/software/make/) to take advantage of shortcuts for running tests.
+
+## Installing Requirements
+- Create your virtual environment by running the following command in a terminal:
+```
+python -m venv .venv
+```
+- Activate the virtual environment:
+```
+source .venv/bin/activate
+```
+- Install the requirements using poetry
+```
+poetry install
+```
+- Check requirements have installed successfully by running:
+```
+poetry show
+```
+All installed requirements will be returned in blue. If any are not installed they will appear as red. Try running `poetry install` again if this happens, or installing the missing packages individually.
+
+## Running the Example script
+From the command line, move to the `/solution` folder:
+```
+cd solution
+```
+
+Then run:
+```
+poetry run python example.py
+```
+
+Follow the instructions to enter the skus of items that need scanning and hit enter to print the total.
+
+## Running Tests
+- To run all tests, from the `solution` folder, run:
+```
+make test
+```
+- To run all tests and receive a coverage report, run:
+```
+make coverage
+```

solution/data/catalogue.yaml

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+ipd:
+  sku: ipd
+  name: Super iPad
+  price: 549.99
+  currency: dollar
+mbp:
+  sku: mbp
+  name: MacBook Pro
+  price: 1399.99
+  currency: dollar
+atv:
+  sku: atv
+  name: Apple TV
+  price: 109.50
+  currency: dollar
+vga:
+  sku: vga
+  name: VGA adapter
+  price: 30.00
+  currency: dollar
+bad-item:
+  sku: bad-item
+  name: Bad Item For Testing

solution/data/specials.yaml

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+FreeItemDeals:
+- name: FreeVGAWithMacBook
+  sku: mbp
+  item_sku: vga
+  purchase_number_required: 1
+  n_free_items: 1 
+BulkDiscountDeals:
+- name: iPadBulkDiscount
+  sku: ipd
+  purchase_number_required: 4
+  new_item_price: 499.99
+NForMDeals:
+- name: Apple3for2
+  sku: atv
+  purchase_number_required: 3
+  number_to_pay_for: 2

solution/example.py

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+import json
+import logging
+
+import yaml
+
+from src.pricing_rules import BulkDiscountDeal, NForMDeal, FreeItemDeal
+from src.checkout import Checkout
+
+logging.basicConfig(level=logging.INFO)
+
+if __name__ == "__main__":
+    # load pricing rules
+    with open("data/specials.yaml") as f:
+        deals = yaml.safe_load(f)
+
+    free_item_deals = deals["FreeItemDeals"]
+    bulk_discount_deals = deals["BulkDiscountDeals"]
+    n_for_m_deals = deals["NForMDeals"]
+
+    pricing_rules = list()
+
+    for deal in free_item_deals:
+        pricing_rules.append(FreeItemDeal(**deal))
+
+    for deal in bulk_discount_deals:
+        pricing_rules.append(BulkDiscountDeal(**deal))
+
+    for deal in n_for_m_deals:
+        pricing_rules.append(NForMDeal(**deal))
+
+    # construct checkout object
+    with open("data/catalogue.yaml") as f:
+        catalogue = yaml.safe_load(f)
+
+    co = Checkout(pricing_rules=pricing_rules, catalogue=catalogue)
+
+    # scan things
+    items_to_scan = input(
+        "Enter the skus of the items you would like to be scanned, separated by a comma: "
+    )
+    items_to_scan = items_to_scan.replace(" ", "")
+    items_to_scan = items_to_scan.split(",")
+    for sku in items_to_scan:
+        co.scan(sku)
+    print(f"Total: ${co.total()}")
+
+    view_receipt = input(
+        "Do you want to see an itemized receipt with discounts applied? (y/n) "
+    )
+    if view_receipt.lower() == "y":
+        print(json.dumps([i.model_dump() for i in co.receipt()], indent=2))

solution/pyproject.toml

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+[tool.poetry]
+name = "dius-shopping"
+version = "0.1.0"
+description = "Solution to the shopping coding challenge created by DIUS for DataRock."
+authors = ["Richa <richa_lad@outlook.com>"]
+readme = "README.md"
+package-mode = false
+
+[tool.poetry.dependencies]
+python = "^3.10"
+pydantic = "^2.9.2"
+pyyaml = "^6.0.2"
+black = "^24.8.0"
+pytest = "^8.3.3"
+pytest-cov = "^5.0.0"
+
+
+[build-system]
+requires = ["poetry-core"]
+build-backend = "poetry.core.masonry.api"

solution/src/checkout.py

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+from typing import List, Dict
+from src.exceptions import ItemNotInCatalogue
+from src.models import PricingRule, Item
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+class Checkout:
+
+    def __init__(self, pricing_rules: List[PricingRule], catalogue: Dict[str, Item]):
+        """Creates Checkout object.
+
+        Args:
+            pricing_rules (List[PricingRule]): A list of rules that specify logic relating to offers.
+            catalogue (Dict[str, Item]): All items available, indexed by their unique sku.
+        """
+        self.pricing_rules = pricing_rules
+        self.scanned_items = list()
+        self.catalogue = catalogue
+
+    def scan(self, item_sku: str) -> None:
+        """Adds an item to the list of items being purchased
+
+        Args:
+            item_sku (str): Unique identifier of the item.
+        """
+        item_attrs = self.catalogue.get(item_sku)
+        if item_attrs is None:
+            raise ItemNotInCatalogue(
+                f"Item with sku {item_sku} not found in catalogue."
+            )
+        item = Item(**item_attrs)
+        self.scanned_items.append(item)
+
+    def total(self) -> float:
+        """Calculates the total sum of all scanned items, with any discounts applied.
+
+        Returns:
+            float: The total cost of the scanned items.
+        """
+        self.items_with_deals = self.scanned_items.copy()
+        for rule in self.pricing_rules:
+            self.items_with_deals = rule.apply(self.items_with_deals)
+        return sum(item.price for item in self.items_with_deals)
+
+    def receipt(self) -> List[Item]:
+        """Returns the list of all scanned items, with any discounts applied.
+
+        Returns:
+            List[Item]: _description_
+        """
+        return self.items_with_deals

solution/src/exceptions.py

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+class ItemNotInCatalogue(Exception):
+    pass

solution/src/models.py

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+from typing import Any, List, Protocol
+from pydantic import BaseModel
+
+
+class Item(BaseModel):
+    sku: str
+    name: str
+    price: float
+    currency: str
+
+    def update(self, attr_to_update: str, new_value: Any):
+        """Returns a new version of the item with the relevant field updated.
+
+        Args:
+            attr_to_update (str): The field to update
+            new_value (Any): The updated value of the field.
+
+        Returns:
+            Item: A new version of the Item.
+        """
+        current = self.model_dump()
+        current[attr_to_update] = new_value
+
+        new = Item(**current)
+
+        return new
+
+
+class PricingRule(Protocol):
+
+    def __init__(self, *args, **kwargs) -> None: ...
+
+    def apply(self, items: List[Item]) -> List[Item]: ...