Show HN: a Rust crate to mock concrete type without using trait

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The approach in this crate is you don't change any thing in your production code but directly mock functions such as std, reqwest and etc.// Production code use std::fs;pub fn claim_slot() -> Result<(), String> { fs::create_dir_all("/var/run/dispatcher") .map_err(|error| format!("cannot claim a slot: {error}")) }// Test codeuse shimforge::{Session, mock}; use std::io;#[test] fn a_denied_slot_is_reported() { let mut session = Session::new(); let mkdir = mock!(session, fs::create_dir_all::<&str>, fn(&str) -> io::Result<()>); mkdir .expect() .with(|path| *path == "/var/run/dispatcher") .once() .returning(|_| Err(io::ErrorKind::PermissionDenied.into()));<pre><code> let error = claim_slot().unwrap_err(); assert!(error.starts_with("cannot claim a slot")); }</code></pre>

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信息来源：Hacker News 新项目
发布时间：2026/9/23 23:46:36

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