Canonicalize headers when creating a HeaderMatcher.

mocktail-tests/tests/examples/http_unary.rs

@@ -1,4 +1,5 @@
 use anyhow::Error;
+use http::HeaderMap;
 use mocktail::prelude::*;
 use serde::{Deserialize, Serialize};
 use test_log::test;
@@ -145,3 +146,41 @@ async fn test_any() -> Result<(), Error> {
 
     Ok(())
 }
+
+#[test(tokio::test)]
+async fn test_unary_headers() -> Result<(), Error> {
+    let mut mocks = MockSet::new();
+    mocks.mock(|when, then| {
+        when.get().headers([
+            ("content-type", "application/json"),
+            ("Accept", "application/json, application/binary"),
+        ]);
+        then.text("yo!");
+    });
+
+    let server = MockServer::new("any").with_mocks(mocks);
+    server.start().await?;
+
+    let client = reqwest::Client::builder().http2_prior_knowledge().build()?;
+
+    let mut headers = HeaderMap::new();
+    headers.insert("content-type", "application/json".parse().unwrap());
+    headers.insert(
+        "accept",
+        "application/json, application/binary".parse().unwrap(),
+    );
+    let response = client
+        .get(server.url("/asdf"))
+        .headers(headers)
+        .send()
+        .await?;
+
+    assert_eq!(response.status(), http::StatusCode::OK);
+    let res = response.text().await?;
+    assert_eq!(res, "yo!");
+
+    let response = client.post(server.url("/whatever")).send().await?;
+    assert_eq!(response.status(), http::StatusCode::NOT_FOUND);
+
+    Ok(())
+}

mocktail/src/headers.rs

@@ -158,13 +158,13 @@ impl PartialEq<str> for HeaderName {
 
 impl From<String> for HeaderName {
     fn from(value: String) -> Self {
-        HeaderName(value)
+        HeaderName(value.to_lowercase())
     }
 }
 
 impl From<&str> for HeaderName {
     fn from(value: &str) -> Self {
-        HeaderName(value.into())
+        HeaderName(value.to_lowercase())
     }
 }
 

mocktail/src/mock_builder/when.rs

@@ -67,6 +67,11 @@ impl When {
     }
 
     /// Headers.
+    ///
+    /// Cannonicalizes passed in header name and values to ensure matching is done in a
+    /// case-insensitive manner as required by [RFC2616][rfc-headers]
+    ///
+    /// [rfc-headers]: https://www.rfc-editor.org/rfc/rfc2616#section-4.2
     pub fn headers<T, U>(self, headers: impl IntoIterator<Item = (T, U)>) -> Self
     where
         T: Into<HeaderName>,