cargotest: Use cargo to determine package name

[lluki]

Execute nearest fails when using a cargo workspace where the package name does not match the directory name fails. cargotest.vim uses the directory name, but a different package name can be specified in the Cargo.toml.
This PR determines the package name using cargo read-manifest.

A minimal example that is fixed by this PR:

Directory structure:

.
├── Cargo.toml
└── pack1
    ├── Cargo.toml
    └── src
        └── main.rs

Cargo.toml

[workspace]
members = [ "pack1", ]

pack1/Cargo.toml

[package]
name = "sim2"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]

pack1/src/main.rs

fn main() {
    println!("Hello, world!");
}

// Execute nearest test on this line
#[test]
fn my_test() {}

[lluki]

Hm. Is adding a dependency to cargo an option for you?

[codeinabox]

Hm. Is adding a dependency to cargo an option for you?

Thank you for this! May I suggest trying to install Cargo as part of the before_script inside .travis.yml. Let me know how you get on

[codeinabox]

I think I have a solution to testing this where we can mock the system call. Could you provide an example of what is returned by cargo read-manifest

[nitnelave]

I think I have a solution to testing this where we can mock the system call. Could you provide an example of what is returned by cargo read-manifest

read-manifest is deprecated. The modern version is something along these lines:

cargo metadata --no-deps --offline --format-version 1

And it returns something like:

{
  "packages": [
    {
      "name": "sim2",
      "version": "0.1.0",
      "id": "sim2 0.1.0 (path+file:///project-root/pack1)",
      "manifest_path": "/project-root/pack1/Cargo.toml",
      "..."
    },
    "..."
  ],
  "workspace_members": [
    "sim2 0.1.0 (path+file:///project-root/pack1)",
    "..."
  ],
  "target_directory": "/project-root/target",
  "version": 1,
  "workspace_root": "/project-root"
}

Does that help?

[codeinabox]

Not forgotten about this, will have a look into it soon

[codeinabox]

I've made a start on trying to mock cargo with an alias though getting some errors, hopefully the answer will reveal itself tomorrow

[codeinabox]

Thank you for your patience on this, I've finally got the mock of cargo read-manifest working so that this should work on CI. However I've discovered that even with cargo installed, this PR is lacking a Cargo.toml in the fixture directory. Could you please add one and update the manifest mock accordingly?

[codeinabox]

This needs to be updated with the output of cargo read-manifest