Fl4m3Ph03n1x
I always thought that the default value for ExUnit.Case, async was true. However in a recent video from ElixirCasts the author states otherwise:
Am I mistaken?
Do I need to use ExUnit.Case, async: true if I want concurrent tests?
I couldn’t find anything in the official docs:
Where Next?
Trending in Questions
Other Trending Topics
Latest on Elixir Forum
Sponsor Spotlight
We build reliable cloud platforms for business-critical systems.
Categories:
Sub Categories:
Forums
Popular Tags
- #ecto
- #liveview
- #troubleshooting
- #learning-elixir
- #library
- #deployment
- #erlang
- #testing
- #genserver
- #mix
- #absinthe
- #remote-other
- #otp
- #plug
- #how-to-question
- #macros
- #postgres
- #elixirconf
- #channels
- #exunit
- #code-sync
- #discussion
- #podcasts
- #javascript
- #onsite
- #dialyzer
- #docker
- #authentication
- #ai
- #umbrella
- #full-time-contract
- #elixirconf-us
- #podcasts-by-brainlid
- #blog-post
- #ecto-query
- #elixir-ls
- #phoenix_html
- #iex
- #graphql
- #genstage
- #websockets
- #supervisor
- #advent-of-code
- #distillery
- #elixirconf-eu
- #processes
- #security
- #api
- #forms
- #performance
Our Sponsors
Build Elixir applications with speed and confidence.
Supporting innovation across the BEAM ecosystem.
Catch errors, track performance, monitor hosts and more.
Error tracking, logs, uptime, and Just Enough APM. Built for developers.
Elixir, Erlang & BEAM conferences from Code Sync. Next: ElixirConf EU 2027
Practical resources that improve the lives of professional developers.
Master modern tools, write cleaner code, and tackle real-world challenges.
**Building the future of software with AI, trust, and human connection.**
The team behind Membrane, Popcorn, LiveDebugger. Available for hire.
Courses that'll move you from confusion to "Aha, now I get it!"
Showing Posts 1 to 5- Show Best Posts
- Show All (oldest first)
- Show All (newest first)
lpil
Looks like it default to
falseelixir/lib/ex_unit/lib/ex_unit/case.ex at 3a3d68385ef02148136ff4b9490c70d3e6d3dbc3 · elixir-lang/elixir · GitHubpeerreynders
ExUnit.Case — ExUnit v1.20.2
tmbb
It defaults to
falselike it should. Elixir doesn’t know whether your test depends on some possibly hidden global state or not. Havingasync: truecould cause some of your tests to fail in unpredictable ways which would be hard to debug.lpil
I’d prefer it to default to concurrent, to nudge us into writing code that is safe to run concurrently by default
hauleth
The problem is that
async: truedoes something different from what people may expect. Tests in single module are always run synchronously, no deviations.async: truemean that tests in given module can be ran in parallel with other modules. So this would produce unexpected results when used with some persistent storage tools, when used without special preparations, or other hard to reason problems. Instead they have chosen to “safer default”. If you want to check your code for concurrency errors then you can check out Concuerror.