runestick 0.3.0

The simple stack-based virtual machine.
Documentation 
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//! The `test` package.
//!
//! Contains functions such as:
//! * `assert` assert that a value is true.

use crate::{ContextError, Module, Panic};
use std::fmt;

#[derive(Debug)]
struct AssertionFailed(String);

impl fmt::Display for AssertionFailed {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(fmt, "assertion failed `{}`", self.0)
    }
}

/// Assert that a value is true.
fn assert(value: bool, message: &str) -> Result<(), Panic> {
    if !value {
        return Err(Panic::custom(AssertionFailed(message.to_string())));
    }

    Ok(())
}

/// Install the core package into the given functions namespace.
pub fn module() -> Result<Module, ContextError> {
    let mut module = Module::new(&["std", "test"]);
    module.function(&["assert"], assert)?;
    Ok(module)
}