Use a dedicated type for form metadata (#14175)

crates/uv-publish/src/lib.rs

@@ -390,7 +390,7 @@ pub async fn upload(
     download_concurrency: &Semaphore,
     reporter: Arc<impl Reporter>,
 ) -> Result<bool, PublishError> {
-    let form_metadata = form_metadata(file, filename)
+    let form_metadata = FormMetadata::read_from_file(file, filename)
         .await
         .map_err(|err| PublishError::PublishPrepare(file.to_path_buf(), Box::new(err)))?;
 
@@ -644,13 +644,17 @@ async fn metadata(file: &Path, filename: &DistFilename) -> Result<Metadata23, Pu
     Ok(Metadata23::parse(&contents)?)
 }
 
-/// Collect the non-file fields for the multipart request from the package METADATA.
-///
-/// Reference implementation: <https://github.com/pypi/warehouse/blob/d2c36d992cf9168e0518201d998b2707a3ef1e72/warehouse/forklift/legacy.py#L1376-L1430>
-async fn form_metadata(
+#[derive(Debug, Clone)]
+struct FormMetadata(Vec<(&'static str, String)>);
+
+impl FormMetadata {
+    /// Collect the non-file fields for the multipart request from the package METADATA.
+    ///
+    /// Reference implementation: <https://github.com/pypi/warehouse/blob/d2c36d992cf9168e0518201d998b2707a3ef1e72/warehouse/forklift/legacy.py#L1376-L1430>
+    async fn read_from_file(
         file: &Path,
         filename: &DistFilename,
-) -> Result<Vec<(&'static str, String)>, PublishPrepareError> {
+    ) -> Result<Self, PublishPrepareError> {
         let hash_hex = hash_file(file, Hasher::from(HashAlgorithm::Sha256)).await?;
 
         let Metadata23 {
@@ -745,7 +749,13 @@ async fn form_metadata(
         add_vec("requires_dist", requires_dist);
         add_vec("requires_external", requires_external);
 
-    Ok(form_metadata)
+        Ok(Self(form_metadata))
+    }
+
+    /// Returns an iterator over the metadata fields.
+    fn iter(&self) -> std::slice::Iter<'_, (&'static str, String)> {
+        self.0.iter()
+    }
 }
 
 /// Build the upload request.
@@ -758,11 +768,11 @@ async fn build_request<'a>(
     registry: &DisplaySafeUrl,
     client: &'a BaseClient,
     credentials: &Credentials,
-    form_metadata: &[(&'static str, String)],
+    form_metadata: &FormMetadata,
     reporter: Arc<impl Reporter>,
 ) -> Result<(RequestBuilder<'a>, usize), PublishPrepareError> {
     let mut form = reqwest::multipart::Form::new();
-    for (key, value) in form_metadata {
+    for (key, value) in form_metadata.iter() {
         form = form.text(*key, value.clone());
     }
 
@@ -888,16 +898,19 @@ async fn handle_response(registry: &Url, response: Response) -> Result<(), Publi
 
 #[cfg(test)]
 mod tests {
-    use crate::{Reporter, build_request, form_metadata};
-    use insta::{assert_debug_snapshot, assert_snapshot};
-    use itertools::Itertools;
     use std::path::PathBuf;
     use std::sync::Arc;
+
+    use insta::{assert_debug_snapshot, assert_snapshot};
+    use itertools::Itertools;
+
     use uv_auth::Credentials;
     use uv_client::BaseClientBuilder;
     use uv_distribution_filename::DistFilename;
     use uv_redacted::DisplaySafeUrl;
 
+    use crate::{FormMetadata, Reporter, build_request};
+
     struct DummyReporter;
 
     impl Reporter for DummyReporter {
@@ -916,7 +929,9 @@ mod tests {
         let file = PathBuf::from("../../scripts/links/").join(raw_filename);
         let filename = DistFilename::try_from_normalized_filename(raw_filename).unwrap();
 
-        let form_metadata = form_metadata(&file, &filename).await.unwrap();
+        let form_metadata = FormMetadata::read_from_file(&file, &filename)
+            .await
+            .unwrap();
 
         let formatted_metadata = form_metadata
             .iter()
@@ -1028,7 +1043,9 @@ mod tests {
         let file = PathBuf::from("../../scripts/links/").join(raw_filename);
         let filename = DistFilename::try_from_normalized_filename(raw_filename).unwrap();
 
-        let form_metadata = form_metadata(&file, &filename).await.unwrap();
+        let form_metadata = FormMetadata::read_from_file(&file, &filename)
+            .await
+            .unwrap();
 
         let formatted_metadata = form_metadata
             .iter()