Why Property Testing Finds Bugs Unit Testing Does Not (2021)

a year ago

Property-Based Testing (PBT) involves testing general properties of a function with randomized inputs rather than specific input-output pairs.
PBT is powerful for testing a wide range of inputs but requires learning how to define properties and generate complex input strategies.
Brian Marick argues that most errors found in testing are either partition errors or boundary errors, which can be addressed with manual unit tests.
PBT's advantage over manual unit testing lies in handling the combinatorial explosion of boundary conditions and edge cases in complex problems.
The complexity of input spaces increases with the number of variables, making it harder to manually identify all edge cases.
Common PBT examples, like testing addition commutativity or list reversal, are too simplistic and don't showcase PBT's real benefits.
Effective PBT examples should involve complex input spaces (e.g., strings, dictionaries) where manual testing might miss edge cases.
Writing good PBT strategies is library-specific, making it harder to generalize skills across different PBT tools.

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