How to configure cargo test with custom arguments in VSCode - unit-testing

Question

I have some tests which create/read/write/delete a file and I always use the same file name in each of them, therefore I need to run them sequentially to avoid simultaneous operations on the same file. In the command line I can just do it like this
cargo test -- --test-threads=1
however in the VSCode Run/Debug menu it doesn't seem to work. I'm using the autogenerated configuration with Rust Analyzer, plus these extra arguments for the sequential run.
This is my launch.json:
{
"version": "0.2.0",
"configurations": [
{
"type": "lldb",
"request": "launch",
"name": "Debug executable 'my-project'",
"cargo": {
"args": [
"build",
"--bin=my-project",
"--package=my-project"
],
"filter": {
"name": "my-project",
"kind": "bin"
}
},
"args": [],
"cwd": "${workspaceFolder}"
},
{
"type": "lldb",
"request": "launch",
"name": "Debug unit tests in executable 'my-project'",
"cargo": {
"args": [
"test",
"--no-run",
"--bin my-project",
"--package my-project",
"--", // here I've added the arguments
"--test-threads=1", // here I've added the arguments
],
"filter": {
"name": "my-project",
"kind": "bin"
}
},
"args": [],
"cwd": "${workspaceFolder}"
}
]
}
And this is the output I get when running the second command (the one which calls cargo test):
Running `cargo test --no-run --bin my-project --package my-project --message-format=json -- --test-threads=1`...
error: Found argument '--bin my-project' which wasn't expected, or isn't valid in this context
Did you mean '--bin'?
If you tried to supply `--bin my-project` as a value rather than a flag, use `-- --bin my-project`
USAGE:
cargo.exe test --no-run --bin [<NAME>]
For more information try --help

Answer 1

VSCode uses a two steps process:
it calls cargo test --no-run to compile the test executable and
it calls the test executable directly.
You should put --test-threads=1 in the last args array:
{
"type": "lldb",
"request": "launch",
"name": "Debug unit tests in executable 'my-project'",
"cargo": {
"args": [
"test",
"--no-run",
"--bin=my-project",
"--package=my-project",
],
"filter": {
"name": "my-project",
"kind": "bin"
}
},
"args": [ "--test-threads=1" ],
"cwd": "${workspaceFolder}"
}