78f08cf983
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> Co-authored-by: hubwriter <hubwriter@github.com>
122 lines
4.1 KiB
Markdown
122 lines
4.1 KiB
Markdown
---
|
|
title: Updating unit tests to match code changes
|
|
shortTitle: Update unit tests
|
|
intro: '{% data variables.copilot.copilot_chat_short %} can help with updating your tests.'
|
|
versions:
|
|
feature: copilot
|
|
category:
|
|
- Testing code
|
|
- Author and optimize with Copilot
|
|
complexity:
|
|
- Intermediate
|
|
octicon: beaker
|
|
topics:
|
|
- Copilot
|
|
contentType: tutorials
|
|
---
|
|
|
|
When you make changes to your code, it's important to update any tests to verify the new behavior and catch any bugs that the new code has introduced. {% data variables.copilot.copilot_chat_short %} can help you quickly update tests to match your code changes, ensuring your test suite stays in sync with your implementation.
|
|
|
|
## Example scenario
|
|
|
|
Imagine you have a Python function, `calculate_discount`, that determines the discount for a given purchase amount. In the original code, you get a 10% discount for amounts over $100. You're making changes to the logic of the function, so that only prices over $150 get a 10% discount, and there's now a 20% discount for amounts over $200.
|
|
|
|
### Original code
|
|
|
|
In the original code, purchase prices above $100 get a 10% discount.
|
|
|
|
```python
|
|
def calculate_discount(amount: float) -> float:
|
|
if amount > 100:
|
|
return amount * 0.1 # 10% discount
|
|
return 0.0
|
|
```
|
|
|
|
### Updated code
|
|
|
|
In the changed code, only amounts above $150 get 10% discount, and amounts above $200 now get a 20% discount.
|
|
|
|
```python id=calculate_discount
|
|
def calculate_discount(amount: float) -> float:
|
|
if amount > 200:
|
|
return amount * 0.2
|
|
elif amount > 150:
|
|
return amount * 0.1
|
|
return 0.0
|
|
```
|
|
|
|
### Existing tests
|
|
|
|
This example shows the existing tests that were written for the original code.
|
|
|
|
```python
|
|
import unittest
|
|
from discount import calculate_discount
|
|
|
|
class TestCalculateDiscount(unittest.TestCase):
|
|
def test_discount_above_100(self):
|
|
# $140 should get a $14 discount (10%)
|
|
self.assertAlmostEqual(calculate_discount(140), 14.0)
|
|
|
|
def test_discount_below_100(self):
|
|
# $80 should get no discount
|
|
self.assertEqual(calculate_discount(80), 0.0)
|
|
|
|
def test_discount_exactly_100(self):
|
|
# $100 is not above 100, so no discount
|
|
self.assertEqual(calculate_discount(100), 0.0)
|
|
|
|
if __name__ == '__main__':
|
|
unittest.main()
|
|
```
|
|
|
|
## Example prompt
|
|
|
|
You can ask {% data variables.copilot.copilot_chat_short %} to identify and update any tests affected by your logic change.
|
|
|
|
```copilot
|
|
Given the update to the `calculate_discount` function, update the unit tests that may fail or become outdated as a result.
|
|
```
|
|
|
|
## Example response
|
|
|
|
{% data reusables.copilot.example-prompts.response-is-an-example %}
|
|
|
|
{% data variables.copilot.copilot_chat_short %} analyzes your code and existing tests, and identifies which tests will fail or are now misleading following your code change.
|
|
|
|
For example, {% data variables.copilot.copilot_chat_short %} explains that:
|
|
* `test_discount_above_100` will now **fail**
|
|
* `test_discount_below_100` and `test_discount_exactly_100` will pass, but they are now **misleading**, since the threshold for the 10% discount is now $150, and not $100.
|
|
|
|
In addition, {% data variables.copilot.copilot_chat_short %} identifies any **missing test coverage**, such as the new 20% discount tier for amounts over $200.
|
|
|
|
{% data variables.copilot.copilot_chat_short %} proposes an updated set of tests.
|
|
|
|
### Updated tests
|
|
|
|
```python
|
|
import unittest
|
|
from discount import calculate_discount
|
|
|
|
class TestCalculateDiscount(unittest.TestCase):
|
|
def test_discount_above_200(self):
|
|
# $250 should get a $50 discount (20%)
|
|
self.assertAlmostEqual(calculate_discount(250), 50.0)
|
|
|
|
def test_discount_above_150(self):
|
|
# $175 should get a $17.50 discount (10%)
|
|
self.assertAlmostEqual(calculate_discount(175), 17.5)
|
|
|
|
def test_discount_at_or_below_150(self):
|
|
# $150 is not above 150, so no discount
|
|
self.assertEqual(calculate_discount(150), 0.0)
|
|
# $80 should get no discount
|
|
self.assertEqual(calculate_discount(80), 0.0)
|
|
|
|
if __name__ == '__main__':
|
|
unittest.main()
|
|
```
|
|
|
|
## Further reading
|
|
|
|
{% data reusables.copilot.example-prompts.further-reading-items %} |