test: Test code in README.md

Author: bahlo

README.md

@@ -12,7 +12,6 @@ Typed accept negotiation for axum, following [RFC7231](https://www.rfc-editor.or
 ```rust
 use axum::{extract::Json, response::{IntoResponse, Response}};
 use axum_accept::AcceptExtractor;
-use serde::Serialize;
 use serde_json::json;
 
 #[derive(AcceptExtractor)]
@@ -25,8 +24,8 @@ enum Accept {
 
 async fn my_handler(accept: Accept) -> Response {
     match accept {
-        TextPlain => "hello world".into_response(),
-        ApplicationJson => Json(json! { "content": "hello_world".to_string() }).into_response(),
+        Accept::TextPlain => "hello world".into_response(),
+        Accept::ApplicationJson => Json(json!({ "content": "hello_world" })).into_response(),
     }
 }
 ```

axum-accept/Cargo.toml

@@ -14,5 +14,6 @@ axum-accept-macros= { version = "0.0.2", path = "../axum-accept-macros" }
 axum-accept-shared = { version = "0.0.2", path = "../axum-accept-shared" }
 
 [dev-dependencies]
-axum = { workspace = true }
+axum = { workspace = true, features = ["json"] }
+serde_json = "1"
 tokio = { version = "1", features = ["macros", "rt-multi-thread"] }

axum-accept/src/lib.rs

@@ -17,6 +17,10 @@
 pub use axum_accept_macros::AcceptExtractor;
 pub use axum_accept_shared::AcceptRejection;
 
+#[cfg(doctest)]
+#[doc = include_str!("../../README.md")]
+pub struct ReadmeDoctests;
+
 #[cfg(test)]
 mod tests {
     use super::*;