Decoupling External Resources in Unit Testing using Mock Traits

pub trait Transceiver {
    fn send_payload(&self, data: &[u8]) -> Result<(), &'static str>;
}
 
pub struct MockTransceiver {
    pub force_failure: bool,
}
 
impl Transceiver for MockTransceiver {
    fn send_payload(&self, data: &[u8]) -> Result<(), &'static str> {
        if self.force_failure || data.is_empty() {
            Err("Network failure simulation")
        } else {
            Ok(())
        }
    }
}
 
#[cfg(test)]
mod tests {
    use super::*;
 
    #[test]
    fn test_payload_handling() {
        let mock = MockTransceiver { force_failure: true };
        assert!(mock.send_payload(b"hello").is_err());
    }
}