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
Some minor things in the paper edition that says “3 2020” on the title page verso, not mentioned in the book’s errata online:
p. 186 But...
New
Running the examples in chapter 5 c under pytest 5.4.1 causes an AttributeError: ‘module’ object has no attribute ‘config’.
In particula...
New
Following the steps described in Chapter 6 of the book, I’m stuck with running the migration as described on page 84:
bundle exec sequel...
New
Hi everyone!
There is an error on the page 71 in the book “Programming machine learning from coding to depp learning” P. Perrotta. You c...
New
A Common-Sense Guide to Data Structures and Algorithms, Second Edition by Jay Wengrow @jaywengrow
Hi,
I have the paperback version of t...
New
I’m running Android Studio “Arctic Fox” 2020.3.1 Patch 2, and I’m embarrassed to admit that I only made it to page 8 before running into ...
New
Is there any place where we can discuss the solutions to some of the exercises? I can figure most of them out, but am having trouble with...
New
The allprojects block listed on page 245 produces the following error when syncing gradle:
“org.gradle.api.GradleScriptException: A prob...
New
Hi all,
currently I wonder how the Tailwind colours work (or don’t work).
For example, in app/views/layouts/application.html.erb I have...
New
Hello @herbert ! Trying to get the very first “Hello, Bracket Terminal!" example to run (p. 53). I develop on an Amazon EC2 instance runn...
New
Other popular topics
Reading something? Working on something? Planning something? Changing jobs even!?
If you’re up for sharing, please let us know what you’...
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
Bought the Moonlander mechanical keyboard. Cherry Brown MX switches. Arms and wrists have been hurting enough that it’s time I did someth...
New
From finance to artificial intelligence, genetic algorithms are a powerful tool with a wide array of applications. But you don't need an ...
New
Start building native Android apps the modern way in Kotlin with Jetpack's expansive set of tools, libraries, and best practices. Learn h...
New
Oh just spent so much time on this to discover now that RancherOS is in end of life but Rancher is refusing to mark the Github repo as su...
New
Use WebRTC to build web applications that stream media and data in real time directly from one user to another, all in the browser.
...
New
Was just curious to see if any were around, found this one:
I got 51/100:
Not sure if it was meant to buy I am sure at times the b...
New
Inside our android webview app, we are trying to paste the copied content from another app eg (notes) using navigator.clipboard.readtext ...
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
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
- /onivim
- /typescript
- /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
- /django
- /deno
- /kubuntu
- /arch-linux
- /nodejs
- /ubuntu
- /spring
- /revery
- /manjaro
- /julia
- /lua
- /diversity
- /markdown
- /v









