Zac Hatfield-Dodds <zac.hatfield.do...@gmail.com> added the comment:
> Okay, well, I'm trying to understand minithesis.py, but I am despairing. The > shrinking code (really everything in class TestingState) is too much to grok. > ... I suppose I have to read the paper at > https://drmaciver.github.io/papers/reduction-via-generation-preview.pdf ... I > am still unclear on some basics too, but presumably it's all related. Shrinking is probably not important to understand, since it's *not* particularly related to anything but implementation details. The abstract of that paper explains why the design is important - integrated shrinking means we can report minimal (easier-to-understand) failing examples with zero user effort, and guarantee that all shrunk examples could have been generated. TestingState is, roughly, the `@given()` decorator internals: responsible for deciding how many times to run the wrapped test function, and how. Note the three phases (generate, target, shrink) - the distribution of examples can depend on the behaviour of the test function on earlier inputs. This is _more_ complex in Hypothesis and thus challenging to document. The important concept is that input examples are generated by a Possibility (ie Strategy), which internally makes a sequence of choices; and that sequence is sourced from a maybe-empty known prefix (e.g. replaying failures, mutating previous inputs) with the suffix determined by a PRNG. I feel like I'm explaining this badly, but there isn't a simple underlying thing to explain - Hypothesis works well because the user API is relatively simple, and then under the hood we have this many-layered stack of implementation details. The synergies and coverage of otherwise-pathological cases this delivers is excellent, but "multiple years and PhDs worth of detailed synergistic work" is just intrinsically complicated. > PS. What does "shortlex" mean? Sort by length, and among equal-length strings sort in the normal (alphabetical) order. For example: A < XY < ABC, etc. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue42109> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
