Writing e2e tests with ink-wrapper
Introduction
While this tutorial focuses on writing e2e (end-to-end) tests, the same approach can be utilized to call your contracts from any backend application written in Rust.
The default tooling for calling contracts provided by subxt
and similar tools relies on runtime checks on input data and received responses. In order to provide compile-time checks as well as easy access to code completion and documentation for contracts, we've developed ink-wrapper
. Simply put, it's a tool that generates a bunch of strongly-typed wrapper code around submitting contract-related transactions. You can include this generated code in your project and use it, instead of calling primitives like subxt
directly.
Setup
To get started you will need to install ink-wrapper
itself (this tutorial uses 0.4.1
so please install the same version to follow along):
In this guide we will write e2e tests for an example PSP22 contract that we use to test ink-wrapper
itself. You will need docker to run a chain for testing and use the tooling provided in the repo to compile contracts. With that:
Finally, let's create a new project that will house our tests:
Generating contract wrappers
The ink-wrapper
takes a .json
metadata file generated while compiling the contract and produces a Rust file based on that. First, setup a node with the contract in question compiled and deployed. This will also run ink-wrapper
's own tests at the end - just ignore that.
Then, invoke ink-wrapper
on the produced .json
metadata file and put the results in the src
directory in the psp22-tests
project:
Notice that we're piping the output of ink-wrapper
through rustfmt
- the output is not guaranteed to be formatted, so in order to commit nicely formatted code into your repo, it's recommended to use this method when regenerating the wrapper files.
Using the wrappers
Now, let's move to the psp22-tests
project. We will need to add some dependencies to make the wrappers compile:
As well as switch to nightly by putting the following in rust-toolchain.toml
:
Attach the module produced by ink-wrapper
to psp22-tests
:
Now add the following test code:
With that, you should be able to run cargo test
and have it pass with 1 test run!
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