mocking struct & mockall_double::double not working as expected

[zaidoon1]

project directory:

src
----> main.rs
----> storage
          --------> client.rs

client.rs:

#[cfg(test)]
use mockall::automock;

pub struct HelloClient {
    client: ....,
}

#[cfg_attr(test, automock)]
impl HelloClient {
......
} 

main.rs:

#[mockall_double::double]
use <project_name>::storage::client::HelloClient;

async fn delete_records(
    records: &[Vec<u8>],
    hello_client: &HelloClient,
) {
xxxx
}

compiler complains with:

unresolved import `<project_name>::storage::client::MockHelloClient`
no `MockHelloClient` in `storage::client`

If I move mockall from dev-dependencies to dependencies in cargo.toml and and update storage.rs to:

#[automock]
impl HelloClient {
......
} 

Things appear to work? But I don't want mockall to be a dependency. What am I doing wrong?

[asomers]

What you posted looks correct. Perhaps the problem lies somewhere else? Are there any other imports?

[zaidoon1]

maybe it's in the mod file?

What I have is:

src
----> main.rs
----> storage
          --------> client.rs
          ---------> mod.rs

my mod.rs looks like:

 pub mod client;

I already posted the entire code for client.rs. I have a lib.rs in the same directory as main.rs that has:

 pub mod storage;

That's pretty much it..

[asomers]

When do you see the error? Is it when you do cargo build or cargo test --bin ? What version of Mockall are you using?

[zaidoon1]

I'm using the latest version 0.12.1. I see it in cargo build, cargo test and vscode linter when i'm looking at the code.

[asomers]

But cargo test does lots of things: unit tests, integration tests, and doc tests. It even checks the examples. That's why I asked specifically for cargo test --bin. That will tell you if your project builds successfully in test mode.

[zaidoon1]

just ran it with cargo test --bin:

error[E0432]: unresolved import `<project_name>::storage::client::MockHelloClient`
  --> src/main.rs:38:5
   |
38 | use < project_name>::storage::client:: HelloClient;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-------------
   |     |                                     |
   |     |                                     help: a similar name exists in the module: `HelloClient`
   |     no `MockHelloClient ` in `storage::client`

For more information about this error, try `rustc --explain E0432`.
error: could not compile `project_name` (bin "project_name" test) due to 1 previous error

[asomers]

That tells you that your project fails to build in test mode. You also said that it fails during cargo build. But that error message doesn't make sense for non-test mode. Are you sure that you get the same error during cargo build?

[zaidoon1]

sorry, that's my bad, cargo build works fine.

[asomers]

Your problem is that your crate contains both a library and a binary. When you build the binary in test mode, the library is built in non-test mode, just like an external dependency. So you need to either:

• Eliminate the library and move everything into the binary
• Make mockall a full dependency, possibly feature-gated, and export the mocks always
• Define the mock structure using mock! in the binary, not #[automock] in the library.

[zaidoon1]

oh i see. thank you!