如何在Rust文档测试中正确引入函数？编译报错求解

错误原因分析 #

你遇到的E0432错误核心有两点：

1. 函数未公开：文档测试默认以外部 crate 的视角执行，非公开（未加pub）的函数无法被外部导入访问。
2. 导入路径不完整：如果函数位于子模块中，crate::开头的路径缺少完整模块层级，导致找不到目标函数。

修复步骤 #

1. 标记函数为公开 #

给目标函数添加pub修饰符，确保外部上下文（包括文档测试）可以访问它：

/// Given an axis in 3D returns the indices of the 3 basis axis in the order such
/// that the first index represents forward (the input) the next the side and the final
/// the up. i.e. it computes the even permutation of basis index that creates the
/// rotation that aligns the basis with the selected axis.
///
/// # Arguments
///
/// * index an index from 0-2 selecting the forward axis.
///
/// # Examples
///
/// ```
/// use crate::axis_index_to_basis_indices;
/// let x_index = 0;
/// let y_index = 1;
/// let z_index = 2;
/// let (forward, side, up) = axis_index_to_basis_indices(x_index);
/// assert!(forward == x_index);
/// assert!(side == y_index);
/// assert!(up == z_index);
///
/// let (forward, side, up) = axis_index_to_basis_indices(z_index);
/// assert!(forward == z_index);
/// assert!(side == x_index);
/// assert!(up == y_index);
/// ```
pub fn axis_index_to_basis_indices(index: i32) -> (i32, i32, i32)
{
    match index
    {
        0 => (0, 1, 2),
        1 => (1, 2, 0),
        2 => (2, 0, 1),
        _ => panic!(),
    }
}

2. 修正导入路径（如果函数在子模块） #

如果你的函数位于dual_contouring.rs子模块中，先在lib.rs里声明该模块：

// lib.rs
pub mod dual_contouring;

然后更新文档测试中的导入路径，补充完整模块层级：

/// # Examples
///
/// ```
/// use crate::dual_contouring::axis_index_to_basis_indices;
/// // 测试代码保持不变
/// ```

额外说明 #

如果不需要将函数对外公开（仅内部测试用），可以在文档测试中使用相对路径super::axis_index_to_basis_indices，但这种方式仅适用于函数和测试在同一模块的场景，且不符合文档测试验证公开接口的设计初衷。

内容的提问来源于stack exchange，提问作者Makogan