运行和记录文档测试情况

[zjp-CN]

目前测试信息不含文档测试，运行它们只需要 cargo test --doc 命令，但解析它们需要额外的技巧，或许可以参考我之前写的解析测试输出的正则表达式：

https://github.com/josecelano/cargo-pretty-test/blob/23e7a940f1e3c4a778f0ed1aebb67a31b5a85c70/src/regex.rs#L30

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轶事 1：Rust For Linux 手动把文档测试抽取成单元测试文件

由于没有直接的方式获取 doc tests 信息，RFL 利用 rustdoc 不稳定的命令行参数手动解析和抽取出文档测试，写入到额外的测试文件。
https://rust-lang.zulipchat.com/#narrow/channel/425075-rust-for-linux/topic/what's.20the.20rustdoc.20hack.3F

/// `rustdoc` generated `file`s look like `sync_locked_by_rs`. Underscores (except the last one)
/// may represent an actual underscore in a directory/file, or a path separator. Thus the actual
/// file might be `sync_locked_by.rs`, `sync/locked_by.rs`, `sync_locked/by.rs` or
/// `sync/locked/by.rs`. This function walks the file system to determine which is the real one.
///
/// This does require that ambiguities do not exist, but that seems fair, especially since this is
/// all supposed to be temporary until `rustdoc` gives us proper metadata to build this. If such
/// ambiguities are detected, they are diagnosed and the script panics.

轶事 2：文档测试的奇怪运行方式甚至不被 nextest 支持 nextest-rs/nextest#16 。