miwa-cli 0.7.0

doc / req / test の3層の仕様乖離（ドリフト）を検知する CLI
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//! Text normalization and content hashing.

/// Normalize line endings (CRLF / CR) to LF. Nothing else is changed.
pub fn normalize(text: &str) -> String {
    text.replace("\r\n", "\n").replace('\r', "\n")
}

/// Normalize `text` and return its SHA-256 hash as `"sha256:<hex>"` (lowercase hex).
pub fn content_hash(text: &str) -> String {
    use sha2::Digest;
    let normalized = normalize(text);
    let mut hasher = sha2::Sha256::new();
    hasher.update(normalized.as_bytes());
    let digest = hasher.finalize();
    format!("sha256:{}", hex::encode(digest))
}

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

    // [FR-001]
    #[test]
    fn crlf_と_lf_は同じハッシュになる() {
        let lf = "line one\nline two\n";
        let crlf = "line one\r\nline two\r\n";
        assert_eq!(content_hash(lf), content_hash(crlf));
    }

    // [FR-001]
    #[test]
    fn content_hash_はsha256プレフィックス付きの小文字hexを返す() {
        let hash = content_hash("hello");
        assert!(hash.starts_with("sha256:"), "unexpected hash: {hash}");
        let hex = hash.strip_prefix("sha256:").unwrap();
        assert_eq!(hex.len(), 64);
        assert!(hex
            .chars()
            .all(|c| c.is_ascii_hexdigit() && !c.is_ascii_uppercase()));
        // 空白除去や大小文字変換のような正規化は行われないため、内容が違えば別ハッシュになる
        assert_ne!(content_hash("hello"), content_hash("hello "));
    }

    // [FR-001]
    #[test]
    fn 単独crもlfと同じハッシュになる() {
        let lf = "a\nb";
        let cr = "a\rb";
        assert_eq!(content_hash(lf), content_hash(cr));
    }
}