restructure source and refactor set_text_body and set_html_body

CLAUDE.md

@@ -0,0 +1,56 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Build Commands
+
+```bash
+cargo build              # Build the library
+cargo build --release    # Build with optimizations (LTO enabled)
+cargo test               # Run all tests
+cargo test test_name     # Run a specific test
+cargo doc --open         # Generate and view documentation
+```
+
+## Architecture
+
+This is a Rust library for parsing, modifying, and serializing email messages (RFC 5322/MIME). It uses copy-on-write semantics to minimize allocations when working with email data.
+
+### Core Types
+
+- **`CowMail<H>`** (`lib.rs`): Main email message struct. Holds headers, body bytes, and nested subparts for multipart messages. Uses `Cow<[u8]>` for zero-copy parsing with owned modifications.
+
+- **`CowMailReader`** (`lib.rs`): Streaming reader implementing `std::io::Read`. Allows efficient serialization without full memory allocation.
+
+- **`CowHeader`** (`header.rs`): Single email header with copy-on-write storage. Tracks byte indices for key/value positions within raw data.
+
+- **`Header` trait** (`header.rs`): Interface for header implementations including parsing, serialization, and RFC 2045 parameter handling.
+
+- **`HeaderMap` trait** (`headers.rs`): Collection operations for headers - find, iterate, add, replace, remove.
+
+- **`Mail` trait** (`lib.rs`): High-level operations for email bodies - content decoding, content-type detection, multipart handling.
+
+- **`CowMailError`** (`lib.rs`): Error type for mail operations (generic errors, parse errors, missing headers).
+
+- **`BodyType`** (`lib.rs`): Enum for body type selection (HTML, PLAIN).
+
+- **`MessageType`** (`lib.rs`): Enum distinguishing SinglePart from MultiPart messages (with boundary).
+
+- **`ContentType`** (`lib.rs`): Wrapper around `ParsedContentType` with conditional defaults for multipart/digest.
+
+### Key Design Patterns
+
+**Copy-on-Write**: Parsed messages borrow from the original byte slice. Only modified fields become owned. The `serialize()` method returns `Vec<Cow<[u8]>>` to preserve this optimization.
+
+**Multipart Handling**: `CowMail` recursively contains `subparts: Vec<CowMail>`. Methods like `make_mixed()`, `make_alternative()`, and `make_related()` transform single-part messages into multipart containers. The original content becomes the first subpart.
+
+**Body Part Navigation**: `get_body_part(BodyType)` traverses the MIME tree to find text/plain or text/html parts, correctly handling `multipart/alternative`, `multipart/related` with `start` parameter, and attachments. The internal `BodyStatus` enum tracks whether a part is a body, not a body, or needs traversal.
+
+### Content Encoding
+
+Body content is automatically encoded/decoded using the `lettre` and `mailparse` crates. `set_content()` automatically selects transfer encoding (quoted-printable for UTF-8 text) and sets appropriate headers.
+
+### High-Level Body Manipulation
+
+- `set_text_body()` / `set_html_body()` / `set_body()`: Intelligently insert or update body parts, creating `multipart/alternative` structures as needed
+- These methods use `get_body_parent_part_mut()` to find the correct insertion point in nested MIME structures

Cargo.toml

@@ -2,7 +2,7 @@
 name = "email-message"
 version = "0.0.1"
 authors = ["Thomas Oettli <spacefreak@noop.ch>"]
-edition = "2021"
+edition = "2024"
 
 [profile.release]
 lto = true

src/header/encoding.rs

@@ -0,0 +1,48 @@
+use std::fmt::Write;
+use email_encoding::headers::writer::EmailWriter;
+
+fn allowed_str(s: &str) -> bool {
+    s.bytes().all(allowed_char)
+}
+
+const fn allowed_char(c: u8) -> bool {
+    c >= 1 && c <= 9 || c == 11 || c == 12 || c >= 14 && c <= 127
+}
+
+fn encode(encode_buf: &mut String, writer: &mut EmailWriter) {
+    if encode_buf.is_empty() {
+        return;
+    }
+
+    let prefix = encode_buf.trim_end_matches(' ');
+    email_encoding::headers::rfc2047::encode(prefix, writer).expect("String is always writable");
+
+    // TODO: add a better API for doing this in email-encoding
+    let spaces = encode_buf.len() - prefix.len();
+    for _ in 0..spaces {
+        writer.space();
+    }
+
+    encode_buf.clear();
+}
+
+pub fn encode_header_value(key: &str, value: &str) -> String {
+    let mut encoded_value = String::new();
+    let line_len = key.len() + ": ".len();
+    let mut writer = EmailWriter::new(&mut encoded_value, line_len, 0, false);
+    let mut encode_buf = String::new();
+    for next_word in value.split_inclusive(' ') {
+        if allowed_str(next_word) {
+            // This word only contains allowed characters
+            // the next word is allowed, but we may have accumulated some words to encode
+            encode(&mut encode_buf, &mut writer);
+            writer.folding().write_str(next_word).expect("String is always writable");
+        } else {
+            // This word contains unallowed characters
+            encode_buf.push_str(next_word);
+        }
+    }
+    encode(&mut encode_buf, &mut writer);
+    drop(writer);
+    encoded_value
+}

src/header/headers.rs

@@ -1,4 +1,4 @@
-use crate::header::{Header, parse_header};
+use super::{Header, parse_header};
 
 pub trait HeaderMap<'a, H: Header<'a> + 'a> {
     fn iter_headers(&'a self, key: &str) -> impl Iterator<Item = &'a H>;
@@ -110,7 +110,7 @@ pub fn parse_headers<'a, H: Header<'a>>(raw_data: &'a [u8]) -> Result<(Vec<H>, u
                 return Err("Headers were followed by an unexpected lone CR character!");
             }
         }
-        let (header, ix_next) = parse_header(&raw_data[ix..]).unwrap();
+        let (header, ix_next) = parse_header(&raw_data[ix..])?;
         headers.push(header);
         ix += ix_next;
     }

src/header/mod.rs

@@ -1,60 +1,15 @@
+mod encoding;
+mod headers;
+
+pub use encoding::encode_header_value;
+pub use headers::{HeaderMap, parse_headers};
+
 use std::borrow::Cow;
 use std::collections::HashMap;
-use std::fmt::{self, Display, Write};
+use std::fmt::{self, Display};
 
 use charset::decode_latin1;
-use email::rfc2045::Rfc2045Parser;
+use email::{FromHeader, rfc2045::Rfc2045Parser};
-use email::FromHeader;
-use email_encoding::headers::writer::EmailWriter;
-
-fn allowed_str(s: &str) -> bool {
-    s.bytes().all(allowed_char)
-}
-
-const fn allowed_char(c: u8) -> bool {
-    c >= 1 && c <= 9 || c == 11 || c == 12 || c >= 14 && c <= 127
-}
-
-fn encode(encode_buf: &mut String, writer: &mut EmailWriter) {
-    if encode_buf.is_empty() {
-        // nothing to encode
-        return;
-    }
-
-    let prefix = encode_buf.trim_end_matches(' ');
-    email_encoding::headers::rfc2047::encode(prefix, writer).expect("String is always writable");
-
-    // TODO: add a better API for doing this in email-encoding
-    let spaces = encode_buf.len() - prefix.len();
-    for _ in 0..spaces {
-        writer.space();
-    }
-
-    encode_buf.clear();
-}
-
-fn encode_header_value(key: &str, value: &str) -> String {
-    let mut encoded_value = String::new();
-    let line_len = key.len() + ": ".len();
-    let mut writer = EmailWriter::new(&mut encoded_value, line_len, 0, false);
-    let mut encode_buf = String::new();
-    for next_word in value.split_inclusive(' ') {
-        if allowed_str(next_word) {
-            // This word only contains allowed characters
-
-            // the next word is allowed, but we may have accumulated some words to encode
-            encode(&mut encode_buf, &mut writer);
-
-            writer.folding().write_str(next_word).expect("String is always writable");
-        } else {
-            // This word contains unallowed characters
-            encode_buf.push_str(next_word);
-        }
-    }
-    encode(&mut encode_buf, &mut writer);
-    drop(writer);
-    encoded_value
-}
 
 pub trait Header<'a>: Clone + Display {
     fn new<K: ToString, V: ToString>(key: K, value: V) -> Self;

src/lib.rs

@@ -1,21 +1,22 @@
 #![forbid(unsafe_code)]
 
 pub mod header;
-pub mod headers;
-use header::CowHeader;
-pub use header::Header;
-use headers::parse_headers;
-pub use headers::HeaderMap;
 
-use lettre::message::header::ContentTransferEncoding;
+#[cfg(test)]
+mod tests;
+
+use header::CowHeader;
+pub use header::{Header, HeaderMap, parse_headers};
+
 use lettre::message::MaybeString;
+use lettre::message::header::ContentTransferEncoding;
 use mailparse::{
-    body::Body, parse_content_disposition, parse_content_type, DispositionType, MailParseError,
+    DispositionType, MailParseError, ParsedContentDisposition, ParsedContentType, body::Body,
-    ParsedContentDisposition, ParsedContentType,
+    parse_content_disposition, parse_content_type,
 };
-pub use mediatype::{names, values, MediaType};
+pub use mediatype::{MediaType, names, values};
-use mediatype::{names::*, values::UTF_8, MediaTypeBuf, Name, ReadParams, WriteParams};
+use mediatype::{MediaTypeBuf, Name, ReadParams, WriteParams, names::*, values::UTF_8};
-use rand::{distr::Alphanumeric, rng, Rng as _};
+use rand::{Rng as _, distr::Alphanumeric, rng};
 use std::borrow::Cow;
 use std::boxed::Box;
 use std::ops::Deref;
@@ -131,11 +132,11 @@ pub trait Mail<'a, T: Header<'a> + 'a>: HeaderMap<'a, T> {
         match ctype.mimetype.parse::<MediaTypeBuf>() {
             Ok(mtype) => {
                 let mut res = MessageType::SinglePart;
-                if mtype.ty() == MULTIPART {
+                if mtype.ty() == MULTIPART
-                    if let Some(boundary) = ctype.params.get("boundary") {
+                    && let Some(boundary) = ctype.params.get("boundary")
+                {
                     res = MessageType::MultiPart(boundary.clone());
                 }
-                }
                 res
             }
             Err(_) => MessageType::SinglePart,
@@ -194,7 +195,7 @@ pub fn generate_boundary() -> String {
 }
 
 /// Result of checking whether a MIME part is a text body (plain/html).
-enum BodyStatus {
+enum BodyCheckStatus {
     /// This part is a text/plain or text/html body (not an attachment)
     IsBody,
     /// This is a leaf node but not a body (attachment, other content type, etc.)
@@ -300,14 +301,14 @@ impl<'a, H: Header<'a> + 'a> CowMail<'a, H> {
     }
 
     /// Check if this MIME part is a text body (plain/html), not a body, or needs traversal.
-    fn body_status(&self, bodytype: Option<BodyType>) -> BodyStatus {
+    fn check_body_status(&self, bodytype: Option<BodyType>) -> BodyCheckStatus {
         match self.is_multipart() {
-            true if self.subparts.is_empty() => BodyStatus::NotBody,
+            true if self.subparts.is_empty() => BodyCheckStatus::NotBody,
-            true => BodyStatus::NeedsTraversal,
+            true => BodyCheckStatus::NeedsTraversal,
             false => {
                 let mime = self.get_mime_type();
                 if mime.ty() != TEXT || self.is_attachment() {
-                    return BodyStatus::NotBody;
+                    return BodyCheckStatus::NotBody;
                 }
 
                 let body_types = match bodytype {
@@ -316,8 +317,8 @@ impl<'a, H: Header<'a> + 'a> CowMail<'a, H> {
                 };
 
                 match body_types.contains(&mime.subty()) {
-                    true => BodyStatus::IsBody,
+                    true => BodyCheckStatus::IsBody,
-                    false => BodyStatus::NotBody,
+                    false => BodyCheckStatus::NotBody,
                 }
             }
         }
@@ -335,30 +336,30 @@ impl<'a, H: Header<'a> + 'a> CowMail<'a, H> {
     }
 
     pub fn get_body_part(&self, bodytype: BodyType) -> Option<&CowMail<'a, H>> {
-        match self.body_status(Some(bodytype)) {
+        match self.check_body_status(Some(bodytype)) {
-            BodyStatus::IsBody => Some(self),
+            BodyCheckStatus::IsBody => Some(self),
-            BodyStatus::NotBody => None,
+            BodyCheckStatus::NotBody => None,
-            BodyStatus::NeedsTraversal => {
+            BodyCheckStatus::NeedsTraversal => {
-                if self.get_mime_type().subty() == RELATED {
+                if self.get_mime_type().subty() == RELATED
-                    if let Some(candidate) = self.get_related_candidate() {
+                    && let Some(candidate) = self.get_related_candidate()
+                {
                     return self.subparts[candidate].get_body_part(bodytype);
                 }
-                }
                 self.subparts.iter().find_map(|p| p.get_body_part(bodytype))
             }
         }
     }
 
     pub fn get_body_part_mut(&mut self, bodytype: BodyType) -> Option<&mut CowMail<'a, H>> {
-        match self.body_status(Some(bodytype)) {
+        match self.check_body_status(Some(bodytype)) {
-            BodyStatus::IsBody => Some(self),
+            BodyCheckStatus::IsBody => Some(self),
-            BodyStatus::NotBody => None,
+            BodyCheckStatus::NotBody => None,
-            BodyStatus::NeedsTraversal => {
+            BodyCheckStatus::NeedsTraversal => {
-                if self.get_mime_type().subty() == RELATED {
+                if self.get_mime_type().subty() == RELATED
-                    if let Some(candidate) = self.get_related_candidate() {
+                    && let Some(candidate) = self.get_related_candidate()
+                {
                     return self.subparts[candidate].get_body_part_mut(bodytype);
                 }
-                }
                 self.subparts.iter_mut().find_map(|p| p.get_body_part_mut(bodytype))
             }
         }
@@ -467,10 +468,10 @@ impl<'a, H: Header<'a> + 'a> CowMail<'a, H> {
 
         for i in subpart_indices {
             let subpart = &self.subparts[i];
-            match subpart.body_status(bodytype) {
+            match subpart.check_body_status(bodytype) {
-                BodyStatus::IsBody => return Some(path.clone()),
+                BodyCheckStatus::IsBody => return Some(path.clone()),
-                BodyStatus::NotBody => continue,
+                BodyCheckStatus::NotBody => continue,
-                BodyStatus::NeedsTraversal => {
+                BodyCheckStatus::NeedsTraversal => {
                     path.push(i);
                     match subpart.find_body_parent_path(path, bodytype) {
                         None => {
@@ -486,10 +487,10 @@ impl<'a, H: Header<'a> + 'a> CowMail<'a, H> {
     }
 
     fn get_body_parent_part_mut(&mut self) -> Option<&mut CowMail<'a, H>> {
-        match self.body_status(None) {
+        match self.check_body_status(None) {
-            BodyStatus::IsBody => Some(self),
+            BodyCheckStatus::IsBody => Some(self),
-            BodyStatus::NotBody => None,
+            BodyCheckStatus::NotBody => None,
-            BodyStatus::NeedsTraversal => match self.find_body_parent_path(&mut Vec::new(), None) {
+            BodyCheckStatus::NeedsTraversal => match self.find_body_parent_path(&mut Vec::new(), None) {
                 Some(path) => {
                     let mut current = self;
                     for idx in path {
@@ -502,25 +503,48 @@ impl<'a, H: Header<'a> + 'a> CowMail<'a, H> {
         }
     }
 
-    pub fn set_text_body<T: ToString>(&mut self, content: T) -> Result<(), CowMailError> {
+    fn set_body_part<T: ToString>(&mut self, content: T, body_type: BodyType) -> Result<(), CowMailError> {
-        if let Some(parent) = self.get_body_parent_part_mut() {
+        let ctype = match body_type {
-            match parent.get_body_part_mut(BodyType::PLAIN) {
+            BodyType::PLAIN => None,
-                Some(part) => part.set_content(content, None),
+            BodyType::HTML => Some(MediaType::new(TEXT, HTML)),
-                None => {
+        };
-                    let mut text_part = Self::new();
-                    text_part.set_content(content, None);
-                    if parent.get_mime_type().subty() == ALTERNATIVE {
-                        parent.subparts.insert(0, text_part);
-                    } else {
-                        let html_part = parent
-                            .get_body_part_mut(BodyType::HTML)
-                            .ok_or(CowMailError::Generic("get_body_parent_part_mut returned a parent without a plain or html body, this should never happen!".into()))?;
-                        html_part.make_alternative(None);
-                        html_part.subparts.insert(0, text_part);
-                    }
-                }
-            }
 
+        if let Some(parent) = self.get_body_parent_part_mut() {
+            match parent.get_body_part_mut(body_type) {
+                Some(part) => part.set_content(content, ctype),
+                None => {
+                    let mut new_part = Self::new();
+                    new_part.set_content(content, ctype);
+                    let parent_mime = parent.get_mime_type();
+                    let parent_subty = parent_mime.subty();
+                    if parent_subty == ALTERNATIVE {
+                        match body_type {
+                            BodyType::PLAIN => parent.subparts.insert(0, new_part),
+                            BodyType::HTML => parent.subparts.push(new_part),
+                        }
+                    } else if parent_subty == RELATED {
+                        parent.make_alternative(None);
+                        match body_type {
+                            BodyType::PLAIN => parent.subparts.insert(0, new_part),
+                            BodyType::HTML => parent.subparts.push(new_part),
+                        }
+                    } else {
+                        let other_type = match body_type {
+                            BodyType::PLAIN => BodyType::HTML,
+                            BodyType::HTML => BodyType::PLAIN,
+                        };
+
+                        let other_part = parent.get_body_part_mut(other_type).ok_or(CowMailError::Generic(
+                            "get_body_parent_part_mut returned a parent without a plain or html body".into(),
+                        ))?;
+                        other_part.make_alternative(None);
+                        match body_type {
+                            BodyType::PLAIN => other_part.subparts.insert(0, new_part),
+                            BodyType::HTML => other_part.subparts.push(new_part),
+                        }
+                    }
+                }
+            }
             return Ok(());
         }
 
@@ -528,44 +552,19 @@ impl<'a, H: Header<'a> + 'a> CowMail<'a, H> {
             self.make_mixed(None);
         }
 
-        let mut text_part = Self::new();
+        let mut new_part = Self::new();
-        text_part.set_content(content, None);
+        new_part.set_content(content, ctype);
-        self.subparts.insert(0, text_part);
+        self.subparts.insert(0, new_part);
 
         Ok(())
     }
 
+    pub fn set_text_body<T: ToString>(&mut self, content: T) -> Result<(), CowMailError> {
+        self.set_body_part(content, BodyType::PLAIN)
+    }
+
     pub fn set_html_body<T: ToString>(&mut self, content: T) -> Result<(), CowMailError> {
-        if let Some(parent) = self.get_body_parent_part_mut() {
+        self.set_body_part(content, BodyType::HTML)
-            match parent.get_body_part_mut(BodyType::HTML) {
-                Some(part) => part.set_content(content, Some(MediaType::new(TEXT, HTML))),
-                None => {
-                    let mut html_part = Self::new();
-                    html_part.set_content(content, Some(MediaType::new(TEXT, HTML)));
-                    if parent.get_mime_type().subty() == ALTERNATIVE {
-                        parent.subparts.push(html_part);
-                    } else {
-                        let text_part = parent
-                            .get_body_part_mut(BodyType::PLAIN)
-                            .ok_or(CowMailError::Generic("get_body_parent_part_mut returned a parent without a plain or html body, this should never happen!".into()))?;
-                        text_part.make_alternative(None);
-                        text_part.subparts.push(html_part);
-                    }
-                }
-            }
-
-            return Ok(());
-        }
-
-        if !self.is_multipart() {
-            self.make_mixed(None);
-        }
-
-        let mut html_part = Self::new();
-        html_part.set_content(content, Some(MediaType::new(TEXT, HTML)));
-        self.subparts.insert(0, html_part);
-
-        Ok(())
     }
 
     pub fn set_body<T: ToString>(&mut self, text: T, html: T) -> Result<(), CowMailError> {
@@ -924,19 +923,6 @@ fn parse_mail_recursive<'a, H: Header<'a> + 'a>(
     Ok(mail)
 }
 
-// Like find_from_u8, but additionally filters such that `key` is at the start
-// of a line (preceded by `\n`) or at the start of the search space.
-fn find_from_u8_line_prefix(line: &[u8], ix_start: usize, key: &[u8]) -> Option<usize> {
-    let mut start = ix_start;
-    while let Some(ix) = find_from_u8(line, start, key) {
-        if ix == ix_start || line[ix - 1] == b'\n' {
-            return Some(ix);
-        }
-        start = ix + 1;
-    }
-    None
-}
-
 fn find_from_u8(line: &[u8], ix_start: usize, key: &[u8]) -> Option<usize> {
     assert!(!key.is_empty());
     assert!(ix_start < line.len());
@@ -963,170 +949,15 @@ fn find_from_u8(line: &[u8], ix_start: usize, key: &[u8]) -> Option<usize> {
     None
 }
 
-#[cfg(test)]
+/// Like find_from_u8, but additionally filters such that `key` is at the start
-mod tests {
+/// of a line (preceded by `\n`) or at the start of the search space.
-    //use std::io::{Read, Write};
+fn find_from_u8_line_prefix(line: &[u8], ix_start: usize, key: &[u8]) -> Option<usize> {
-    use crate::{names::HTML, names::TEXT, CowHeader, CowMail, Header, HeaderMap, Mail, MediaType};
+    let mut start = ix_start;
-
+    while let Some(ix) = find_from_u8(line, start, key) {
-    #[test]
+        if ix == ix_start || line[ix - 1] == b'\n' {
-    fn test_header_mutations() {
+            return Some(ix);
-        let mut mail = CowMail::<CowHeader>::new();
-        assert_eq!(mail.headers.len(), 0);
-
-        let test_headers = vec![
-            ("X-Test", "Test"),
-            ("X-Another-Test", "Another"),
-            ("X-Test", "Test2"),
-            ("X-Another-Test", "Another1"),
-            ("X-Test", "Test3"),
-        ];
-
-        for (key, value) in test_headers.iter() {
-            mail.add_header(key, value);
         }
-
+        start = ix + 1;
-        assert_eq!(mail.headers.len(), test_headers.len());
-        for (idx, header) in mail.headers.iter().enumerate() {
-            assert_eq!(header.get_key(), test_headers[idx].0);
-            assert_eq!(header.get_value(), test_headers[idx].1);
-        }
-
-        mail.insert_header("X-Test", "Test1", 1);
-        assert_eq!(
-            mail.iter_values("X-Test").collect::<Vec<_>>(),
-            ["Test", "Test1", "Test2", "Test3"]
-        );
-
-        mail.replace_all_headers("X-Test", "Test555");
-        assert_eq!(
-            mail.iter_values("X-Test").collect::<Vec<_>>(),
-            ["Test555", "Test555", "Test555", "Test555"]
-        );
-
-        mail.replace_header("X-Test", "Test", 0);
-        mail.replace_header("X-Test", "Test1", 1);
-        mail.replace_header("X-Test", "Test2", 2);
-        mail.replace_header("X-Test", "Test3", 3);
-        assert_eq!(
-            mail.iter_values("X-Test").collect::<Vec<_>>(),
-            ["Test", "Test1", "Test2", "Test3"]
-        );
-
-        mail.remove_header("X-Test", 1);
-        assert_eq!(
-            mail.iter_values("X-Test").collect::<Vec<_>>(),
-            ["Test", "Test2", "Test3"]
-        );
-        mail.remove_all_headers("X-Test");
-        assert_eq!(mail.headers.len(), 2);
-    }
-
-    #[test]
-    fn test_body_mutations() {
-        let mut mail =
-            CowMail::try_from(concat!("Content-Type: text/plain\n", "\n", "This is a test message").as_bytes())
-                .unwrap();
-        let ctype = mail.content_type();
-        assert_eq!(ctype.mimetype, "text/plain");
-        assert_eq!(ctype.charset, "us-ascii");
-        assert_eq!(mail.is_multipart(), false);
-        assert_eq!(mail.get_content().unwrap(), "This is a test message");
-
-        mail.clear_content();
-        assert!(mail.find_header("Content-Type").is_none());
-        assert_eq!(mail.get_content().unwrap(), "");
-        mail.set_content("This is a new test message ❤\n".to_string(), None);
-        let ctype = mail.content_type();
-        assert_eq!(ctype.mimetype, "text/plain");
-        assert_eq!(ctype.charset, "UTF-8");
-
-        mail.clear_content();
-        assert_eq!(mail.get_content().unwrap(), "");
-        mail.set_content("This is a new test message\n".to_string(), None);
-        let ctype = mail.content_type();
-        assert_eq!(ctype.mimetype, "text/plain");
-        assert_eq!(ctype.charset, "us-ascii");
-
-        mail.add_header("From", "\"John Doe\" <john.doe@example.com>");
-
-        let mut html = CowMail::new();
-        html.set_content(
-            "<html><body>This is a new test message ☺</body></html>".to_string(),
-            Some(MediaType::new(TEXT, HTML)),
-        );
-
-        mail.add_alternative(html);
-        let alt_boundary = mail.get_boundary().unwrap();
-
-        let ctype = mail.content_type();
-        assert_eq!(ctype.mimetype, "multipart/alternative");
-        assert_eq!(ctype.params.get("boundary").unwrap(), &alt_boundary);
-        assert_eq!(
-            mail.find_header("Content-Type").unwrap().get_value(),
-            format!("multipart/alternative; boundary=\"{}\"", alt_boundary)
-        );
-
-        let mut attachment = CowMail::new();
-        attachment.set_content("This is a test text file".to_string(), None);
-        let mut disp = CowHeader::new("Content-Disposition", "attachment");
-        disp.set_param("filename", "Test☺File.html");
-        attachment.headers.push(disp);
-        mail.add_attachment(attachment);
-
-        let mixed_boundary = mail.get_boundary().unwrap();
-        let encoded = mail
-            .serialize()
-            .iter()
-            .flat_map(|p| p.into_iter())
-            .cloned()
-            .collect::<Vec<u8>>();
-
-        let expected = format!(
-            "From: \"John Doe\" <john.doe@example.com>\r\n\
-             MIME-Version: 1.0\r\n\
-             Content-Type: multipart/mixed;\r\n boundary=\"{mixed_boundary}\"\r\n\
-             \r\n\
-             --{mixed_boundary}\r\n\
-             Content-Type: multipart/alternative;\r\n boundary=\"{alt_boundary}\"\r\n\
-             \r\n\
-             --{alt_boundary}\r\n\
-             Content-Type: text/plain\r\n\
-             \r\n\
-             This is a new test message\r\n\
-             \r\n\
-             --{alt_boundary}\r\n\
-             Content-Type: text/html; charset=UTF-8\r\n\
-             Content-Transfer-Encoding: quoted-printable\r\n\
-             \r\n\
-             <html><body>This is a new test message =E2=98=BA</body></html>\r\n\
-             --{alt_boundary}--\r\n\
-             --{mixed_boundary}\r\n\
-             Content-Type: text/plain\r\n\
-             Content-Disposition: attachment;\r\n filename=\"=?utf-8?b?VGVzdOKYukZpbGUuaHRtbA==?=\"\r\n\
-             \r\n\
-             This is a test text file\r\n\
-             --{mixed_boundary}--\r\n"
-        );
-        let expected = expected.into_bytes();
-
-        assert_eq!(encoded, expected);
-
-        /*
-                let mut f = std::fs::File::open("/tmp/test.eml").unwrap();
-                let mut data = Vec::new();
-                f.read_to_end(&mut data).unwrap();
-
-                let mail = CowMail::try_from(&data[..]).unwrap();
-                let mut serialized = mail
-                    .serialize()
-                    .iter()
-                    .flat_map(|p| p.into_iter())
-                    .cloned()
-                    .collect::<Vec<u8>>();
-
-                assert_eq!(data, serialized);
-                let mut f = std::fs::File::create("/tmp/test1.eml").unwrap();
-                f.write_all(&mut serialized).unwrap();
-        */
     }
+    None
 }

src/tests.rs

@@ -0,0 +1,164 @@
+    //use std::io::{Read, Write};
+    use crate::{CowHeader, CowMail, Header, HeaderMap, Mail, MediaType, names::HTML, names::TEXT};
+
+    #[test]
+    fn test_header_mutations() {
+        let mut mail = CowMail::<CowHeader>::new();
+        assert_eq!(mail.headers.len(), 0);
+
+        let test_headers = vec![
+            ("X-Test", "Test"),
+            ("X-Another-Test", "Another"),
+            ("X-Test", "Test2"),
+            ("X-Another-Test", "Another1"),
+            ("X-Test", "Test3"),
+        ];
+
+        for (key, value) in test_headers.iter() {
+            mail.add_header(key, value);
+        }
+
+        assert_eq!(mail.headers.len(), test_headers.len());
+        for (idx, header) in mail.headers.iter().enumerate() {
+            assert_eq!(header.get_key(), test_headers[idx].0);
+            assert_eq!(header.get_value(), test_headers[idx].1);
+        }
+
+        mail.insert_header("X-Test", "Test1", 1);
+        assert_eq!(
+            mail.iter_values("X-Test").collect::<Vec<_>>(),
+            ["Test", "Test1", "Test2", "Test3"]
+        );
+
+        mail.replace_all_headers("X-Test", "Test555");
+        assert_eq!(
+            mail.iter_values("X-Test").collect::<Vec<_>>(),
+            ["Test555", "Test555", "Test555", "Test555"]
+        );
+
+        mail.replace_header("X-Test", "Test", 0);
+        mail.replace_header("X-Test", "Test1", 1);
+        mail.replace_header("X-Test", "Test2", 2);
+        mail.replace_header("X-Test", "Test3", 3);
+        assert_eq!(
+            mail.iter_values("X-Test").collect::<Vec<_>>(),
+            ["Test", "Test1", "Test2", "Test3"]
+        );
+
+        mail.remove_header("X-Test", 1);
+        assert_eq!(
+            mail.iter_values("X-Test").collect::<Vec<_>>(),
+            ["Test", "Test2", "Test3"]
+        );
+        mail.remove_all_headers("X-Test");
+        assert_eq!(mail.headers.len(), 2);
+    }
+
+    #[test]
+    fn test_body_mutations() {
+        let mut mail =
+            CowMail::try_from(concat!("Content-Type: text/plain\n", "\n", "This is a test message").as_bytes())
+                .unwrap();
+        let ctype = mail.content_type();
+        assert_eq!(ctype.mimetype, "text/plain");
+        assert_eq!(ctype.charset, "us-ascii");
+        assert_eq!(mail.is_multipart(), false);
+        assert_eq!(mail.get_content().unwrap(), "This is a test message");
+
+        mail.clear_content();
+        assert!(mail.find_header("Content-Type").is_none());
+        assert_eq!(mail.get_content().unwrap(), "");
+        mail.set_content("This is a new test message ❤\n".to_string(), None);
+        let ctype = mail.content_type();
+        assert_eq!(ctype.mimetype, "text/plain");
+        assert_eq!(ctype.charset, "UTF-8");
+
+        mail.clear_content();
+        assert_eq!(mail.get_content().unwrap(), "");
+        mail.set_content("This is a new test message\n".to_string(), None);
+        let ctype = mail.content_type();
+        assert_eq!(ctype.mimetype, "text/plain");
+        assert_eq!(ctype.charset, "us-ascii");
+
+        mail.add_header("From", "\"John Doe\" <john.doe@example.com>");
+
+        let mut html = CowMail::new();
+        html.set_content(
+            "<html><body>This is a new test message ☺</body></html>".to_string(),
+            Some(MediaType::new(TEXT, HTML)),
+        );
+
+        mail.add_alternative(html);
+        let alt_boundary = mail.get_boundary().unwrap();
+
+        let ctype = mail.content_type();
+        assert_eq!(ctype.mimetype, "multipart/alternative");
+        assert_eq!(ctype.params.get("boundary").unwrap(), &alt_boundary);
+        assert_eq!(
+            mail.find_header("Content-Type").unwrap().get_value(),
+            format!("multipart/alternative; boundary=\"{}\"", alt_boundary)
+        );
+
+        let mut attachment = CowMail::new();
+        attachment.set_content("This is a test text file".to_string(), None);
+        let mut disp = CowHeader::new("Content-Disposition", "attachment");
+        disp.set_param("filename", "Test☺File.html");
+        attachment.headers.push(disp);
+        mail.add_attachment(attachment);
+
+        let mixed_boundary = mail.get_boundary().unwrap();
+        let encoded = mail
+            .serialize()
+            .iter()
+            .flat_map(|p| p.into_iter())
+            .cloned()
+            .collect::<Vec<u8>>();
+
+        let expected = format!(
+            "From: \"John Doe\" <john.doe@example.com>\r\n\
+             MIME-Version: 1.0\r\n\
+             Content-Type: multipart/mixed;\r\n boundary=\"{mixed_boundary}\"\r\n\
+             \r\n\
+             --{mixed_boundary}\r\n\
+             Content-Type: multipart/alternative;\r\n boundary=\"{alt_boundary}\"\r\n\
+             \r\n\
+             --{alt_boundary}\r\n\
+             Content-Type: text/plain\r\n\
+             \r\n\
+             This is a new test message\r\n\
+             \r\n\
+             --{alt_boundary}\r\n\
+             Content-Type: text/html; charset=UTF-8\r\n\
+             Content-Transfer-Encoding: quoted-printable\r\n\
+             \r\n\
+             <html><body>This is a new test message =E2=98=BA</body></html>\r\n\
+             --{alt_boundary}--\r\n\
+             --{mixed_boundary}\r\n\
+             Content-Type: text/plain\r\n\
+             Content-Disposition: attachment;\r\n filename=\"=?utf-8?b?VGVzdOKYukZpbGUuaHRtbA==?=\"\r\n\
+             \r\n\
+             This is a test text file\r\n\
+             --{mixed_boundary}--\r\n"
+        );
+        let expected = expected.into_bytes();
+
+        assert_eq!(encoded, expected);
+
+        /*
+                let mut f = std::fs::File::open("/tmp/test.eml").unwrap();
+                let mut data = Vec::new();
+                f.read_to_end(&mut data).unwrap();
+
+                let mail = CowMail::try_from(&data[..]).unwrap();
+                let mut serialized = mail
+                    .serialize()
+                    .iter()
+                    .flat_map(|p| p.into_iter())
+                    .cloned()
+                    .collect::<Vec<u8>>();
+
+                assert_eq!(data, serialized);
+                let mut f = std::fs::File::create("/tmp/test1.eml").unwrap();
+                f.write_all(&mut serialized).unwrap();
+        */
+    }