rustkas
Property-Based Testing with PropEr, Erlang, and Elixir: Finding a simplified case of inconsistency (page 146)
I noticed that the necessary inconsistence, which describes in an example PropEr framework does not find a discrepancy in the RFC 4180 specification, is far from at once. I was surprised when I ran the property several times and didn’t get the error I was looking for.
$ rebar3 proper
===> Testing prop_csv:prop_roundtrip()
....................................................................................................
OK: Passed 100 test(s).
===>
1/1 properties passed
When I increased the number of tests to 1000, the framework reproduced the necessary use case.
$ rebar3 proper -n 1000
===> Testing prop_csv:prop_roundtrip()
..........................!
Failed: After 27 test(s).
[#{[40,36] => []},#{[40,36] => []}]
Shrinking .......(7 time(s))
[#{[66,65] => []},#{[66,65] => []}]
===>
0/1 properties passed, 1 failed
===> Failed test cases:
prop_csv:prop_roundtrip() -> false
PropEr can help us in it better. As we know about a possible problem we can narrow Size to 1. For this task we can add simplified generator and property-based test:
%%%%%%%%%%%%%%%%%%
%%% Properties %%%
%%%%%%%%%%%%%%%%%%
prop_roundtrip_01() ->
?FORALL(Maps,
csv_source_01(),
Maps
=:= bday_csv:decode(
bday_csv:encode(Maps))).
%%%%%%%%%%%%%%%%%%
%%% Generators %%%
%%%%%%%%%%%%%%%%%%
csv_source_01() ->
?LET(Keys, header(1), list(entry(1, Keys))).
Launching that property we get the expected error has gotten every time:
$ rebar3 proper -d apps/bday/test -p prop_roundtrip_01
===> Linking _build/default/plugins/rebar3_format to _build/test/plugins/rebar3_format
===> Linking _build/default/plugins/katana_code to _build/test/plugins/katana_code
===> Verifying dependencies...
===> Linking _build/default/plugins/covertool to _build/test/plugins/covertool
===> Compiling bday
===> Testing prop_csv:prop_roundtrip_01()
.......!
Failed: After 8 test(s).
[#{[125] => [75,85,50]},#{[125] => []},#{[125] => []}]
Shrinking ......(6 time(s))
[#{[65] => []},#{[65] => []}]
===>
0/1 properties passed, 1 failed
===> Failed test cases:
prop_csv:prop_roundtrip_01() -> false
Popular Pragmatic Bookshelf topics
Title: Hands-on Rust: question about get_component (page 295)
(feel free to respond. “You dug you’re own hole… good luck”)
I have somet...
New
Hi,
build fails on:
bracket-lib = “~0.8.1”
when running on Mac Mini M1 Rust version 1.5.0:
Compiling winit v0.22.2
error[E0308]: mi...
New
Page 28: It implements io.ReaderAt on the store type.
Sorry if it’s a dumb question but was the io.ReaderAt supposed to be io.ReadAt?
...
New
Hi! I know not the intentions behind this narrative when called, on page XI:
mount() |> handle_event() |> render()
but the correc...
New
Hello! Thanks for the great book.
I was attempting the Trie (chap 17) exercises and for number 4 the solution provided for the autocorre...
New
#book-python-testing-with-pytest-second-edition
Hi. Thanks for writing the book. I am just learning so this might just of been an issue ...
New
When installing Cards as an editable package, I get the following error:
ERROR: File “setup.py” not found. Directory cannot be installe...
New
Hi,
I am getting an error I cannot figure out on my test.
I have what I think is the exact code from the book, other than I changed “us...
New
@mfazio23
I’m following the indications of the book and arriver ad chapter 10, but the app cannot be compiled due to an error in the Bas...
New
I just bought this book to learn about Android development, and I’m already running into a major issue in Ch. 1, p. 20: “Update activity...
New
Other popular topics
Which, if any, games do you play? On what platform?
I just bought (and completed) Minecraft Dungeons for my Nintendo Switch. Other than ...
New
I am thinking in building or buy a desktop computer for programing, both professionally and on my free time, and my choice of OS is Linux...
New
I am asking for any distro that only has the bare-bones to be able to get a shell in the server and then just install the packages as we ...
New
In case anyone else is wondering why Ruby 3 doesn’t show when you do asdf list-all ruby :man_facepalming: do this first:
asdf plugin-upd...
New
Intensively researching Erlang books and additional resources on it, I have found that the topic of using Regular Expressions is either c...
New
I am trying to crate a game for the Nintendo switch, I wanted to use Java as I am comfortable with that programming language. Can you use...
New
Author Spotlight:
Peter Ullrich
@PJUllrich
Data is at the core of every business, but it is useless if nobody can access and analyze ...
New
Author Spotlight:
Bruce Tate
@redrapids
Programming languages always emerge out of need, and if that’s not always true, they’re defin...
New
Explore the power of Ash Framework by modeling and building the domain for a real-world web application.
Rebecca Le @sevenseacat and ...
New
Woke up to this today: Claude Code’s complete source code exposed via npm source map. Not a snippet. All 512,000 lines. 1,900 TypeScript ...
New
Latest in Property-Based Testing with PropEr, Erlang, and Elixir
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /wasm
- /ruby
- /erlang
- /phoenix
- /keyboards
- /python
- /js
- /rails
- /security
- /go
- /swift
- /vim
- /clojure
- /java
- /emacs
- /haskell
- /svelte
- /typescript
- /onivim
- /kotlin
- /c-plus-plus
- /crystal
- /tailwind
- /react
- /gleam
- /ocaml
- /flutter
- /elm
- /vscode
- /ash
- /html
- /opensuse
- /deepseek
- /zig
- /centos
- /php
- /scala
- /react-native
- /lisp
- /sublime-text
- /textmate
- /nixos
- /debian
- /agda
- /deno
- /django
- /kubuntu
- /arch-linux
- /nodejs
- /ubuntu
- /spring
- /revery
- /manjaro
- /julia
- /lua
- /diversity
- /markdown
- /c









