Add config option to specify toolchain

[calebcartwright]

I'll often use rustup override to explicitly set the toolchain to use in a project directory (particularly for projects like rustfmt and clippy that often need a specific nightly version), but the cargo commands we're invoking in a newly spawned process for test discovery/execution don't seem to be picking that up.

I suspect that adding a rust-toolchain file would work, though I don't think we should fail to work without one. Let's add a config option to allow explicitly specifying toolchain

[JRAndreassen]

I have the same issue...

It seems to not honor the directives in the "toolchain" file in the project directory...
Do you run the cargo command from the directory or direct reference ?

The issue when to a workspace cargo.toml in the parent...
cwd is set to parent dir, location of the workspace toml...

[calebcartwright]

It seems to not honor the directives in the "toolchain" file in the project directory...

Would you please open a new issue? This issue is primarily about adding a config option, and I would prefer to debug any issues you are having in a separate, dedicated issue.

Do you run the cargo command from the directory or direct reference ?

The cargo invocations are executed in the directory of the corresponding Cargo.toml as needed. In the case of cargo test... commands, these are executed in the same directory of the Cargo.toml file for the respective package, regardless of whether it's a single package project or a workspace project.

vscode-rust-test-adapter/src/cargo.ts

Lines 36 to 39 in aac7721

	const execArgs: ExecOptions = {
	cwd: targetWorkspace,
	maxBuffer
	};

The issue when to a workspace cargo.toml in the parent...
cwd is set to parent dir, location of the workspace toml...

Sorry, I have no idea what you're trying to say there.