refactor: extract common make_dep_path to cargo_util

crates/cargo-test-support/src/registry.rs

@@ -1,6 +1,6 @@
 use crate::git::repo;
 use crate::paths;
-use cargo_util::Sha256;
+use cargo_util::{registry::make_dep_path, Sha256};
 use flate2::write::GzEncoder;
 use flate2::Compression;
 use std::collections::BTreeMap;
@@ -627,12 +627,7 @@ impl Package {
         }
         let line = json.to_string();
 
-        let file = match self.name.len() {
-            1 => format!("1/{}", self.name),
-            2 => format!("2/{}", self.name),
-            3 => format!("3/{}/{}", &self.name[..1], self.name),
-            _ => format!("{}/{}/{}", &self.name[0..2], &self.name[2..4], self.name),
-        };
+        let file = make_dep_path(&self.name, false);
 
         let registry_path = if self.alternative {
             alt_registry_path()

crates/cargo-util/src/lib.rs

@@ -9,6 +9,7 @@ pub mod paths;
 mod process_builder;
 mod process_error;
 mod read2;
+pub mod registry;
 mod sha256;
 
 /// Whether or not this running in a Continuous Integration environment.

crates/cargo-util/src/registry.rs

@@ -0,0 +1,45 @@
+/// Make a path to a dependency, which aligns to
+///
+/// - [index from of Cargo's index on filesystem][1], and
+/// - [index from Crates.io][2].
+///
+/// [1]: https://docs.rs/cargo/latest/cargo/sources/registry/index.html#the-format-of-the-index
+/// [2]: https://github.com/rust-lang/crates.io-index
+pub fn make_dep_path(dep_name: &str, prefix_only: bool) -> String {
+    let (slash, name) = if prefix_only {
+        ("", "")
+    } else {
+        ("/", dep_name)
+    };
+    match dep_name.len() {
+        1 => format!("1{}{}", slash, name),
+        2 => format!("2{}{}", slash, name),
+        3 => format!("3/{}{}{}", &dep_name[..1], slash, name),
+        _ => format!("{}/{}{}{}", &dep_name[0..2], &dep_name[2..4], slash, name),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::make_dep_path;
+
+    #[test]
+    fn prefix_only() {
+        assert_eq!(make_dep_path("a", true), "1");
+        assert_eq!(make_dep_path("ab", true), "2");
+        assert_eq!(make_dep_path("abc", true), "3/a");
+        assert_eq!(make_dep_path("Abc", true), "3/A");
+        assert_eq!(make_dep_path("AbCd", true), "Ab/Cd");
+        assert_eq!(make_dep_path("aBcDe", true), "aB/cD");
+    }
+
+    #[test]
+    fn full() {
+        assert_eq!(make_dep_path("a", false), "1/a");
+        assert_eq!(make_dep_path("ab", false), "2/ab");
+        assert_eq!(make_dep_path("abc", false), "3/a/abc");
+        assert_eq!(make_dep_path("Abc", false), "3/A/Abc");
+        assert_eq!(make_dep_path("AbCd", false), "Ab/Cd/AbCd");
+        assert_eq!(make_dep_path("aBcDe", false), "aB/cD/aBcDe");
+    }
+}

src/cargo/sources/registry/index.rs

@@ -72,7 +72,7 @@ use crate::sources::registry::{RegistryData, RegistryPackage, INDEX_V_MAX};
 use crate::util::interning::InternedString;
 use crate::util::{internal, CargoResult, Config, Filesystem, OptVersionReq, ToSemver};
 use anyhow::bail;
-use cargo_util::paths;
+use cargo_util::{paths, registry::make_dep_path};
 use log::{debug, info};
 use semver::Version;
 use std::collections::{HashMap, HashSet};
@@ -373,12 +373,7 @@ impl<'cfg> RegistryIndex<'cfg> {
             .chars()
             .flat_map(|c| c.to_lowercase())
             .collect::<String>();
-        let raw_path = match fs_name.len() {
-            1 => format!("1/{}", fs_name),
-            2 => format!("2/{}", fs_name),
-            3 => format!("3/{}/{}", &fs_name[..1], fs_name),
-            _ => format!("{}/{}/{}", &fs_name[0..2], &fs_name[2..4], fs_name),
-        };
+        let raw_path = make_dep_path(&fs_name, false);
 
         // Attempt to handle misspellings by searching for a chain of related
         // names to the original `raw_path` name. Only return summaries

src/cargo/sources/registry/remote.rs

@@ -9,7 +9,7 @@ use crate::util::errors::CargoResult;
 use crate::util::interning::InternedString;
 use crate::util::{Config, Filesystem};
 use anyhow::Context as _;
-use cargo_util::{paths, Sha256};
+use cargo_util::{paths, registry::make_dep_path, Sha256};
 use lazycell::LazyCell;
 use log::{debug, trace};
 use std::cell::{Cell, Ref, RefCell};
@@ -21,15 +21,6 @@ use std::mem;
 use std::path::Path;
 use std::str;
 
-fn make_dep_prefix(name: &str) -> String {
-    match name.len() {
-        1 => String::from("1"),
-        2 => String::from("2"),
-        3 => format!("3/{}", &name[..1]),
-        _ => format!("{}/{}", &name[0..2], &name[2..4]),
-    }
-}
-
 /// A remote registry is a registry that lives at a remote URL (such as
 /// crates.io). The git index is cloned locally, and `.crate` files are
 /// downloaded as needed and cached locally.
@@ -279,7 +270,7 @@ impl<'cfg> RegistryData for RemoteRegistry<'cfg> {
         {
             write!(url, "/{}/{}/download", CRATE_TEMPLATE, VERSION_TEMPLATE).unwrap();
         }
-        let prefix = make_dep_prefix(&*pkg.name());
+        let prefix = make_dep_path(&*pkg.name(), true);
         let url = url
             .replace(CRATE_TEMPLATE, &*pkg.name())
             .replace(VERSION_TEMPLATE, &pkg.version().to_string())
@@ -343,18 +334,3 @@ impl<'cfg> Drop for RemoteRegistry<'cfg> {
         self.tree.borrow_mut().take();
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use super::make_dep_prefix;
-
-    #[test]
-    fn dep_prefix() {
-        assert_eq!(make_dep_prefix("a"), "1");
-        assert_eq!(make_dep_prefix("ab"), "2");
-        assert_eq!(make_dep_prefix("abc"), "3/a");
-        assert_eq!(make_dep_prefix("Abc"), "3/A");
-        assert_eq!(make_dep_prefix("AbCd"), "Ab/Cd");
-        assert_eq!(make_dep_prefix("aBcDe"), "aB/cD");
-    }
-}