Gain insights into property-based testing with PropEr in Elixir. Learn foundational principles, custom data generators, and advanced concepts for effective real-world application testing.

Property Based Testing with PropEr in Elixr_468 x 60 copy.png

propert-based-testing.tar.gz

Erlang

Elixer

Erlang-Chap2

Elixir-Chap2

Erlang-Shell

erlang-user

elixir-user

elixir-shell

elrang-eunit

erlang-chap5-employee

elixir-cover_test

erlang-cover_test

erlang-chap10-databaseinit

erlang-chap10-user

elixir-chap10-user

erlang-chap10-shell

elixir-chap10-shell

erlang-chap10-dbsetup

elixir-chap10-dbSetup

erlang-chap5-templating

erlang-chap5-last

elixir-chap5-last

erlang-chap10-default

elixir-chap10-default

elixir-chap10-default-copy

Erlang-Chap2-copy

Elixir-Chap2-copy

Erlang-Shell-copy

elixir-shell-copy

erlang-default-force

elixir-default-force

erlang-test-shell

elxir-test-shell

Property-based testing relies on specifying some property of code, unlike unit tests, which specify the expected output in response to some inputs. In this course, we'll cover the concepts we need to feel confident about using even the most advanced features of PropEr with Elixir.

We'll start with the basic and foundational principles of property-based testing, see what the framework offers us to get started, make our way through thinking in properties, write our own custom data generators, and then learn more advanced concepts. We'll also see how you can use property-based testing in a realistic project.

By the time we finish this course, we should feel comfortable testing real-world applications using properties.

Property-Based Testing with PropEr in Elixir

# Summary

This chapter has shown us the basics of stateful property testing, based on a single simple model. We’ve been through the two phases of the testing:
1) Symbolic testing, where the model is used to generate a sequence of commands that represents what the system should do.
2) Real testing, where the symbolic sequence of commands is applied to the real system, and the results compared with what the model expects.

We’ve put these concepts in practice through a cache server modeled as a first-in-first-out list and showed that the model seems to hold fine under sequential operations. We've then seen how PropEr can take that same exact model and create a parallel version of it that could, with some amount of help, find concurrency bugs in our cache program.

# What's next

We’ve seen the base mechanism of how stateful properties work, but truth be told, the cache example we used resulted in a rather simple model. In the next chapter, we’ll experiment with a more complex stateful system based on SQL queries, with varying amounts of determinism. We’ll move past the basics of stateful properties and explore more advanced techniques to handle the complexity of modeling large systems for integration tests.

Here's a summary of what we learned in this chapter.

Wrapping Up

Foundations of Property-Based Testing

Writing Properties

Thinking in Properties

Custom Generators

Responsible Testing

Properties-Driven Development

Shrinking

Stateful Properties

Case Study: Bookstore

State Machine Properties

Conclusion

Wrapping Up

Summary