moonlit-pdk 0.2.0

//! Optional validation of a plugin's `config:` block, run at `init`.

/// Semantic validation for a plugin's `config:`, beyond what decoding checks.
///
/// `moonlit_plugin!` calls [`validate`](PluginConfig::validate) once the config
/// has decoded. The returned message surfaces verbatim as the `init` error,
/// where a decode failure would be wrapped in `"invalid plugin config: ..."`.
///
/// # Examples
///
/// ```
/// use moonlit_pdk::PluginConfig;
///
/// #[derive(Default)]
/// struct Cfg { token: String }
///
/// impl PluginConfig for Cfg {
///     fn validate(&self) -> Result<(), String> {
///         if self.token.is_empty() {
///             return Err("github: `token` is required".into());
///         }
///         Ok(())
///     }
/// }
///
/// assert_eq!(
///     Cfg::default().validate(),
///     Err("github: `token` is required".to_string())
/// );
/// ```
pub trait PluginConfig {
  /// Validate the decoded config.
  ///
  /// # Errors
  ///
  /// Return `Err(msg)` to fail `init`. `msg` is shown to the user unchanged.
  fn validate(&self) -> Result<(), String> {
    Ok(())
  }
}

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

  struct Cfg {
    token: String,
  }
  impl PluginConfig for Cfg {
    fn validate(&self) -> Result<(), String> {
      if self.token.trim().is_empty() {
        return Err("token is required.".to_string());
      }
      Ok(())
    }
  }

  #[test]
  fn blank_value_returns_verbatim_message() {
    let msg = (Cfg { token: "  ".into() })
      .validate()
      .expect_err("blank token must fail validation");
    assert_eq!(msg, "token is required.");
  }

  #[test]
  fn present_value_passes() {
    assert!((Cfg { token: "abc".into() }).validate().is_ok());
  }

  #[test]
  fn default_impl_accepts() {
    struct Bare;
    impl PluginConfig for Bare {}
    assert!(Bare.validate().is_ok());
  }
}