Behaviour Driven Development¶
By Malcolm Tredennick
Why have I asked you here today¶
- Testing landscape
- A different way to think about this
- Stubs is empty data
- Mocking is pretend versions of data
Substitute for external systems & components
Need to be injected into the tests
- “monkey patching”
- Dependency injection
Problem: Mocks need to be kept in synch with reality
I’ve run into this with mocks. This is why Open Comparison includes real API calls to it’s target systems.
test everything you can think of
- no bug fix without a test
Test Driven Development (TDD)
- Wraite failing test for next method or clas
- Write minimal code to make test pass
- Rinse, wash, repeat
- Kind of drives Malolm crazy
- Really about “specification, not verification”
Documentation Driven Development (DDD)
Behavior Driven Development (BDD)
Here we go!
- On paper
- Capturing the idea is probably good
- “What was I thinking when I cooked this up?”
As a [user or role] I want [feature] so that [something happens]
What is the next most important thing the code should do?
- Need to be able to test
- Need to be able to run
Given that [initial context], if and when [some event occurs], then [ensure some outcomes]
Interlude: Naming things¶
- Language helps guide our brain
- Focuses the mind
- Perhaps too exclusively
The Sapir-Whorf Hypothesis
class BasicFieldTests(TestCase): def test_field_name(self): ... def test_show_hidden_fields(self): ...
class Fields(TestCase): def show_allow_name_override(self): ... class ChoiceFields(TestCase): def should_permit_initial_values_in_hidden_widgets(self): ...
- write a load_test that changes the test_ prefix with should_ prefix
- Cause language matters
Closing thoughts on unittest¶
- Create more test classes
- Make them more explicit
DSL Packages for testing¶
- Lettuce (via PyPI)
- Freshen (via PyPI)
These tools are unique and probably good showing to non-coder types with money.
- Behavioral tests are worth trying
- Question the way you think from time to time
- Are your tests’ purpose clear to the future you?