Failing to render colored space characters

[willhansen]

Result with cargo test:

This is the correct output.

The debug-printed string there is "\n\u{1b}[48;2;0;127;0m \u{1b}[49m\n\u{1b}[48;2;0;127;0m \u{1b}[49m\n"

---

Result with bacon test:

Note that the green rectangle is missing.

---

Code:

fn main() {
    println!("Hello World!");
}


#[cfg(test)]
pub mod test {
    #[test]
    fn test_a() {
        let set_bg = "\u{1b}[48;2;0;127;0m";
        let reset_bg = "\u{1b}[49m";
        let spaces = " ".repeat(20);
        let the_string = format!(
            "
{set_bg}{spaces}{reset_bg}
{set_bg}{spaces}{reset_bg}
"
        );
        dbg!(&the_string);
        println!("{}", the_string);
        panic!();
    }
}

Cargo.toml:

[package]
name = "hello-world"
version = "0.1.0"
edition = "2021"

versions:

bash-5.2$ cargo --version
cargo 1.88.0 (873a06493 2025-05-10)
bash-5.2$ bacon --version
bacon 3.16.0
bash-5.2$ rustc --version
rustc 1.88.0 (6b00bc388 2025-06-23) (built from a source tarball)

flake.nix:

{
  description = "rust workspace";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      let pkgs = import nixpkgs { inherit system; };
      in {
        devShells.default = pkgs.mkShell {
          buildInputs = with pkgs; [
            cargo
            rustc
            bacon
          ];
        };
      });
}

flake.lock file:

{
  "nodes": {
    "flake-utils": {
      "inputs": {
        "systems": "systems"
      },
      "locked": {
        "lastModified": 1731533236,
        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
        "owner": "numtide",
        "repo": "flake-utils",
        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
        "type": "github"
      },
      "original": {
        "owner": "numtide",
        "repo": "flake-utils",
        "type": "github"
      }
    },
    "nixpkgs": {
      "locked": {
        "lastModified": 1753432016,
        "narHash": "sha256-cnL5WWn/xkZoyH/03NNUS7QgW5vI7D1i74g48qplCvg=",
        "owner": "NixOS",
        "repo": "nixpkgs",
        "rev": "6027c30c8e9810896b92429f0092f624f7b1aace",
        "type": "github"
      },
      "original": {
        "owner": "NixOS",
        "ref": "nixpkgs-unstable",
        "repo": "nixpkgs",
        "type": "github"
      }
    },
    "root": {
      "inputs": {
        "flake-utils": "flake-utils",
        "nixpkgs": "nixpkgs"
      }
    },
    "systems": {
      "locked": {
        "lastModified": 1681028828,
        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
        "owner": "nix-systems",
        "repo": "default",
        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
        "type": "github"
      },
      "original": {
        "owner": "nix-systems",
        "repo": "default",
        "type": "github"
      }
    }
  },
  "root": "root",
  "version": 7
}