Help: Cannot make parse_from working correctly with positional arguments?

[linrongbin16]

Hi, I'm trying to parse positional arguments (for example, 0 or more file names) with clap. Here's the definition of the cli:

use clap::Parser;

#[derive(Parser, Debug)]
#[command(version, about, long_about=None)]
pub struct Cli {
  #[arg(help = "Edit file(s)")]
  file: Vec<String>,
}

#[cfg(test)]
mod tests {
  use super::*;

  #[test]
  fn test_cli() {
    let input = vec![
      vec!["README.md"],
    ] as Vec<Vec<&str>>;
    let expect = vec![
      Cli {
        file: vec!["README.md".to_string()],
      },
    ];

    assert_eq!(input.len(), expect.len());
    let n = input.len();
    for i in 0..n {
      let actual = Cli::parse_from(&input[i]);
      println!("actual-{i}: {:?}", actual);
      println!("expect-{i}: {:?}", expect[i]);
      assert_eq!(actual.file, expect[i].file);
    }
  }
}

However, the test case is failed:

Woud you please help me with that?

[linrongbin16]

Update:

I found the reason: when use the parse_from API, the first item should be the command name itself.