├── README.md
├── item_database.py
├── shopping_cart.py
└── test_shopping_cart.py


/README.md:
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 1 | # Simple Pytest Example
 2 | 
 3 | This is the code for my video tutorial for getting started with Pytest.
 4 | 
 5 | * [Pytest Documentation](https://docs.pytest.org/en/6.2.x/getting-started.html#getstarted)
 6 | * [unittest.mock Documentation](https://docs.python.org/3/library/unittest.mock.html)
 7 | 
 8 | ### Install Pytest
 9 | 
10 | ```bash
11 | pip install pytest
12 | ```
13 | 
14 | ### Run the tests
15 | 
16 | ```bash
17 | pytest
18 | ```
19 | 
20 | ### Run a specific file
21 | 
22 | ```bash
23 | pytest test_shopping_cart.py
24 | ```
25 | 
26 | ### Run a specific test
27 | 
28 | ```bash
29 | pytest test_shopping_cart.py::test_can_get_total_price
30 | ```
31 | 


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/item_database.py:
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1 | class ItemDatabase:
2 |     def __init__(self) -> None:
3 |         pass
4 | 
5 |     def get(self, item: str) -> float:
6 |         pass
7 | 


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/shopping_cart.py:
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 1 | from typing import List
 2 | 
 3 | 
 4 | class ShoppingCart:
 5 |     def __init__(self, max_size: int) -> None:
 6 |         self.items: List[str] = []
 7 |         self.max_size = max_size
 8 | 
 9 |     def add(self, item: str):
10 |         if self.size() == self.max_size:
11 |             raise OverflowError("cannot add more items")
12 |         self.items.append(item)
13 | 
14 |     def size(self) -> int:
15 |         return len(self.items)
16 | 
17 |     def get_items(self) -> List[str]:
18 |         return self.items
19 | 
20 |     def get_total_price(self, price_map):
21 |         total_price = 0
22 |         for item in self.items:
23 |             total_price += price_map.get(item)
24 |         return total_price
25 | 


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/test_shopping_cart.py:
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 1 | from unittest.mock import Mock
 2 | from item_database import ItemDatabase
 3 | from shopping_cart import ShoppingCart
 4 | import pytest
 5 | 
 6 | 
 7 | @pytest.fixture
 8 | def cart():
 9 |     # All setup for the cart here...
10 |     return ShoppingCart(5)
11 | 
12 | 
13 | def test_can_add_item_to_cart(cart):
14 |     cart.add("apple")
15 |     assert cart.size() == 1
16 | 
17 | 
18 | def test_when_item_added_then_cart_contains_item(cart):
19 |     cart.add("apple")
20 |     assert "apple" in cart.get_items()
21 | 
22 | 
23 | def test_when_add_more_than_max_items_should_fail(cart):
24 |     for _ in range(5):
25 |         cart.add("apple")
26 | 
27 |     with pytest.raises(OverflowError):
28 |         cart.add("apple")
29 | 
30 | 
31 | def test_can_get_total_price(cart):
32 |     cart.add("apple")
33 |     cart.add("orange")
34 |     item_database = ItemDatabase()
35 | 
36 |     def mock_get_item(item: str):
37 |         if item == "apple":
38 |             return 1.0
39 |         if item == "orange":
40 |             return 2.0
41 | 
42 |     item_database.get = Mock(side_effect=mock_get_item)
43 |     assert cart.get_total_price(item_database) == 3.0
44 | 


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