Property-based testing: The lazy programmer's guide to writing thousands of tests

Transcript

1. Pierre Goudjo Property-based testing The lazy programmer's guide to writing thousands of tests
2. “Real-life” Scenario
26. Solution
27. What’s an addition?
30. Properties Addition • Associativity: x+(y+z) = (x+y)+z • Commutativity: x + y = y + x • Identity Element: x+0 = x
31. This is property-based testing
32. for any (x, y, …) such as precondition(x, y, …) holds property(x, y, …) is true
33. Let’s implement this!!!!
34. Is it useful?
35. Avg • for any number (a and b ) • such a <= b • a <= avg(a, b) and avg(a, b) <= b • for any number (a and b ) • such a <= b • avg(a, b) == avg(a, b)
36. Zip/Unzip • for any string (x) • such as x not “” • unzip(zip(x)) == x is true