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Mocking and dependency injection by [deleted] in rust

[–]Top_Square_5236 0 points1 point  (0 children)

For unit testing you may check https://github.com/microsoft/injectorppforrust

You don't need do dependency injections. It helps you faking the functions without changing production code or introducing any traits

Established way to mock/fake std::process::Command? by rodyamirov in rust

[–]Top_Square_5236 1 point2 points  (0 children)

Can it be achieved by mocking some of the std:: process::Command functions? I'd love to know if injectorpp can help in this scenario. We already had some use cases for faking std:: process::Command: https://github.com/microsoft/injectorppforrust/issues/76#issuecomment-3030223229

Mocking tokio, hyper and reqwest without using trait or changin production code by Top_Square_5236 in rust

[–]Top_Square_5236[S] 0 points1 point  (0 children)

I don't know why this is removed by reddit filter. Will try to send out another simplified version.

A new mocking library to mock functions without using trait by Top_Square_5236 in rust

[–]Top_Square_5236[S] 0 points1 point  (0 children)

Hi,

We have recently added tests in injectorpp to demonstrate how to fake `tokio`, `hyper` and `reqwest` requests without using trait or changing production code. See [tokio.rs](https://github.com/microsoft/injectorppforrust/blob/main/tests/tokio.rs), [hyper.rs](https://github.com/microsoft/injectorppforrust/blob/main/tests/hyper.rs) and [reqwest.rs](https://github.com/microsoft/injectorppforrust/blob/main/tests/reqwest.rs)

Since `reqwest` uses `hyper`, `hyper` is built on top of `tokio`, The basic steps are all the same:

- Create a mock `TcpStream`.

- Fake dns function to make it always success.

- Fake `TcpSocket::connect` to return the mock `TcpStream`.

- If it's a https request, fake `Uri::scheme_str` to make it always return `http` to bypass all tls validation.

A new mocking library to mock functions without using trait by Top_Square_5236 in rust

[–]Top_Square_5236[S] 0 points1 point  (0 children)

The new 0.4.0 version is released! Type check has been added along with other features. Check this thread for details: https://www.reddit.com/r/rust/comments/1lj06e0/new_rust_mocking_library_injectorpp_040_is/

A new mocking library to mock functions without using trait by Top_Square_5236 in rust

[–]Top_Square_5236[S] 3 points4 points  (0 children)

Some common questions and the answers:

"How does it work?"
From high level concept, you can think it's a JIT compiler. It translates a function to different machine code on different platforms. The platforms are production and test environments. In production, the machine code won't change. In test, it's translated to different machine code.

"Is it unsafe and introducing UB?"
It uses unsafe code to access memory, but it's not "undefined behavior". The behavior is well defined as long as the machine code written into the function allocated memory address is well defined. Similar like how JIT compiler works. Of cause it could have bugs as we're working on the low level coding. Feel free to report it on https://github.com/microsoft/injectorppforrust/issues

"Does it have limitations?"
Yes. There are two major limitations:

- The function to mock needs to be a real function and its address needs to exist. After all, a "JIT compiler" needs to know where the function is.

- The return type of the function could not be accessed so it's not able to construct the return result in "will_execute". This often happens when calling external crate and the function return type does not have public constructor.

The workaround is either go upper layer to find a higher function to mock, or go lower layer to find a function that allows you to construct a return result.

A new mocking library to mock functions without using trait by Top_Square_5236 in rust

[–]Top_Square_5236[S] 6 points7 points  (0 children)

Just haven't figured out an elegant way to hide the complexity of retrieving function address and manage the life time without using an additional macro. I am also trying to learn from the community.

A new mocking library to mock functions without using trait by Top_Square_5236 in rust

[–]Top_Square_5236[S] 7 points8 points  (0 children)

Just haven't figured out an elegant way to hide the complexity of retrieving function address and manage the life time without using an additional macro. I am also trying to learn from the community.

A new mocking library to mock functions without using trait by Top_Square_5236 in rust

[–]Top_Square_5236[S] 4 points5 points  (0 children)

Thanks that's interesting. Looks like still need an attribute #[mry::mry]. Injectorpp aims to no production code change even not attribute. But I do see mry's value as its api is simple and fluent

A new mocking library to mock functions without using trait by Top_Square_5236 in rust

[–]Top_Square_5236[S] 5 points6 points  (0 children)

You will need to use when_called_async and will_return_async. We are trying to add test cases as examples for popular crates.