refactor(npm): create `cli::npm::managed` module (#20740)

Creates the `cli::npm::managed` module and starts moving more
functionality into it.

1 files changed, 780 insertions, 0 deletions

diff --git a/cli/npm/managed/resolvers/local.rs b/cli/npm/managed/resolvers/local.rs
new file mode 100644
index 000000000..57170eccd
--- /dev/null
+++ b/cli/npm/managed/resolvers/local.rs
@@ -0,0 +1,780 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+//! Code for local node_modules resolution.
+
+use std::borrow::Cow;
+use std::cmp::Ordering;
+use std::collections::HashMap;
+use std::collections::HashSet;
+use std::fs;
+use std::path::Path;
+use std::path::PathBuf;
+use std::sync::Arc;
+
+use crate::cache::CACHE_PERM;
+use crate::npm::cache::mixed_case_package_name_decode;
+use crate::util::fs::atomic_write_file;
+use crate::util::fs::canonicalize_path_maybe_not_exists_with_fs;
+use crate::util::fs::symlink_dir;
+use crate::util::fs::LaxSingleProcessFsFlag;
+use crate::util::progress_bar::ProgressBar;
+use crate::util::progress_bar::ProgressMessagePrompt;
+use async_trait::async_trait;
+use deno_ast::ModuleSpecifier;
+use deno_core::anyhow::bail;
+use deno_core::anyhow::Context;
+use deno_core::error::AnyError;
+use deno_core::unsync::spawn;
+use deno_core::unsync::JoinHandle;
+use deno_core::url::Url;
+use deno_npm::resolution::NpmResolutionSnapshot;
+use deno_npm::NpmPackageCacheFolderId;
+use deno_npm::NpmPackageId;
+use deno_npm::NpmResolutionPackage;
+use deno_npm::NpmSystemInfo;
+use deno_runtime::deno_core::futures;
+use deno_runtime::deno_fs;
+use deno_runtime::deno_node::NodePermissions;
+use deno_runtime::deno_node::NodeResolutionMode;
+use deno_runtime::deno_node::PackageJson;
+use deno_semver::package::PackageNv;
+use serde::Deserialize;
+use serde::Serialize;
+
+use crate::npm::cache::mixed_case_package_name_encode;
+use crate::npm::NpmCache;
+use crate::util::fs::copy_dir_recursive;
+use crate::util::fs::hard_link_dir_recursive;
+
+use super::super::resolution::NpmResolution;
+use super::common::types_package_name;
+use super::common::NpmPackageFsResolver;
+use super::common::RegistryReadPermissionChecker;
+
+/// Resolver that creates a local node_modules directory
+/// and resolves packages from it.
+#[derive(Debug)]
+pub struct LocalNpmPackageResolver {
+  fs: Arc<dyn deno_fs::FileSystem>,
+  cache: Arc<NpmCache>,
+  progress_bar: ProgressBar,
+  resolution: Arc<NpmResolution>,
+  registry_url: Url,
+  root_node_modules_path: PathBuf,
+  root_node_modules_url: Url,
+  system_info: NpmSystemInfo,
+  registry_read_permission_checker: RegistryReadPermissionChecker,
+}
+
+impl LocalNpmPackageResolver {
+  pub fn new(
+    fs: Arc<dyn deno_fs::FileSystem>,
+    cache: Arc<NpmCache>,
+    progress_bar: ProgressBar,
+    registry_url: Url,
+    node_modules_folder: PathBuf,
+    resolution: Arc<NpmResolution>,
+    system_info: NpmSystemInfo,
+  ) -> Self {
+    Self {
+      fs: fs.clone(),
+      cache,
+      progress_bar,
+      resolution,
+      registry_url,
+      root_node_modules_url: Url::from_directory_path(&node_modules_folder)
+        .unwrap(),
+      root_node_modules_path: node_modules_folder.clone(),
+      system_info,
+      registry_read_permission_checker: RegistryReadPermissionChecker::new(
+        fs,
+        node_modules_folder,
+      ),
+    }
+  }
+
+  fn resolve_package_root(&self, path: &Path) -> PathBuf {
+    let mut last_found = path;
+    loop {
+      let parent = last_found.parent().unwrap();
+      if parent.file_name().unwrap() == "node_modules" {
+        return last_found.to_path_buf();
+      } else {
+        last_found = parent;
+      }
+    }
+  }
+
+  fn resolve_folder_for_specifier(
+    &self,
+    specifier: &ModuleSpecifier,
+  ) -> Result<Option<PathBuf>, AnyError> {
+    let Some(relative_url) =
+      self.root_node_modules_url.make_relative(specifier)
+    else {
+      return Ok(None);
+    };
+    if relative_url.starts_with("../") {
+      return Ok(None);
+    }
+    // it's within the directory, so use it
+    let Some(path) = specifier.to_file_path().ok() else {
+      return Ok(None);
+    };
+    // Canonicalize the path so it's not pointing to the symlinked directory
+    // in `node_modules` directory of the referrer.
+    canonicalize_path_maybe_not_exists_with_fs(&path, |path| {
+      self
+        .fs
+        .realpath_sync(path)
+        .map_err(|err| err.into_io_error())
+    })
+    .map(Some)
+    .map_err(|err| err.into())
+  }
+}
+
+#[async_trait]
+impl NpmPackageFsResolver for LocalNpmPackageResolver {
+  fn root_dir_url(&self) -> &Url {
+    &self.root_node_modules_url
+  }
+
+  fn node_modules_path(&self) -> Option<PathBuf> {
+    Some(self.root_node_modules_path.clone())
+  }
+
+  fn package_folder(&self, id: &NpmPackageId) -> Result<PathBuf, AnyError> {
+    match self.resolution.resolve_pkg_cache_folder_id_from_pkg_id(id) {
+      // package is stored at:
+      // node_modules/.deno/<package_cache_folder_id_folder_name>/node_modules/<package_name>
+      Some(cache_folder_id) => Ok(
+        self
+          .root_node_modules_path
+          .join(".deno")
+          .join(get_package_folder_id_folder_name(&cache_folder_id))
+          .join("node_modules")
+          .join(&cache_folder_id.nv.name),
+      ),
+      None => bail!(
+        "Could not find package information for '{}'",
+        id.as_serialized()
+      ),
+    }
+  }
+
+  fn resolve_package_folder_from_package(
+    &self,
+    name: &str,
+    referrer: &ModuleSpecifier,
+    mode: NodeResolutionMode,
+  ) -> Result<PathBuf, AnyError> {
+    let Some(local_path) = self.resolve_folder_for_specifier(referrer)? else {
+      bail!("could not find npm package for '{}'", referrer);
+    };
+    let package_root_path = self.resolve_package_root(&local_path);
+    let mut current_folder = package_root_path.as_path();
+    loop {
+      current_folder = current_folder.parent().unwrap();
+      let node_modules_folder = if current_folder.ends_with("node_modules") {
+        Cow::Borrowed(current_folder)
+      } else {
+        Cow::Owned(current_folder.join("node_modules"))
+      };
+      let sub_dir = join_package_name(&node_modules_folder, name);
+      if self.fs.is_dir_sync(&sub_dir) {
+        // if doing types resolution, only resolve the package if it specifies a types property
+        if mode.is_types() && !name.starts_with("@types/") {
+          let package_json = PackageJson::load_skip_read_permission(
+            &*self.fs,
+            sub_dir.join("package.json"),
+          )?;
+          if package_json.types.is_some() {
+            return Ok(sub_dir);
+          }
+        } else {
+          return Ok(sub_dir);
+        }
+      }
+
+      // if doing type resolution, check for the existence of a @types package
+      if mode.is_types() && !name.starts_with("@types/") {
+        let sub_dir =
+          join_package_name(&node_modules_folder, &types_package_name(name));
+        if self.fs.is_dir_sync(&sub_dir) {
+          return Ok(sub_dir);
+        }
+      }
+
+      if current_folder == self.root_node_modules_path {
+        bail!(
+          "could not find package '{}' from referrer '{}'.",
+          name,
+          referrer
+        );
+      }
+    }
+  }
+
+  fn resolve_package_folder_from_specifier(
+    &self,
+    specifier: &ModuleSpecifier,
+  ) -> Result<Option<PathBuf>, AnyError> {
+    let Some(local_path) = self.resolve_folder_for_specifier(specifier)? else {
+      return Ok(None);
+    };
+    let package_root_path = self.resolve_package_root(&local_path);
+    Ok(Some(package_root_path))
+  }
+
+  fn resolve_package_cache_folder_id_from_specifier(
+    &self,
+    specifier: &ModuleSpecifier,
+  ) -> Result<Option<NpmPackageCacheFolderId>, AnyError> {
+    let Some(folder_path) =
+      self.resolve_package_folder_from_specifier(specifier)?
+    else {
+      return Ok(None);
+    };
+    let folder_name = folder_path.parent().unwrap().to_string_lossy();
+    Ok(get_package_folder_id_from_folder_name(&folder_name))
+  }
+
+  async fn cache_packages(&self) -> Result<(), AnyError> {
+    sync_resolution_with_fs(
+      &self.resolution.snapshot(),
+      &self.cache,
+      &self.progress_bar,
+      &self.registry_url,
+      &self.root_node_modules_path,
+      &self.system_info,
+    )
+    .await
+  }
+
+  fn ensure_read_permission(
+    &self,
+    permissions: &dyn NodePermissions,
+    path: &Path,
+  ) -> Result<(), AnyError> {
+    self
+      .registry_read_permission_checker
+      .ensure_registry_read_permission(permissions, path)
+  }
+}
+
+/// Creates a pnpm style folder structure.
+async fn sync_resolution_with_fs(
+  snapshot: &NpmResolutionSnapshot,
+  cache: &Arc<NpmCache>,
+  progress_bar: &ProgressBar,
+  registry_url: &Url,
+  root_node_modules_dir_path: &Path,
+  system_info: &NpmSystemInfo,
+) -> Result<(), AnyError> {
+  if snapshot.is_empty() {
+    return Ok(()); // don't create the directory
+  }
+
+  let deno_local_registry_dir = root_node_modules_dir_path.join(".deno");
+  let deno_node_modules_dir = deno_local_registry_dir.join("node_modules");
+  fs::create_dir_all(&deno_node_modules_dir).with_context(|| {
+    format!("Creating '{}'", deno_local_registry_dir.display())
+  })?;
+
+  let single_process_lock = LaxSingleProcessFsFlag::lock(
+    deno_local_registry_dir.join(".deno.lock"),
+    // similar message used by cargo build
+    "waiting for file lock on node_modules directory",
+  )
+  .await;
+
+  // load this after we get the directory lock
+  let mut setup_cache =
+    SetupCache::load(deno_local_registry_dir.join(".setup-cache.bin"));
+
+  let pb_clear_guard = progress_bar.clear_guard(); // prevent flickering
+
+  // 1. Write all the packages out the .deno directory.
+  //
+  // Copy (hardlink in future) <global_registry_cache>/<package_id>/ to
+  // node_modules/.deno/<package_folder_id_folder_name>/node_modules/<package_name>
+  let package_partitions =
+    snapshot.all_system_packages_partitioned(system_info);
+  let mut handles: Vec<JoinHandle<Result<(), AnyError>>> =
+    Vec::with_capacity(package_partitions.packages.len());
+  let mut newest_packages_by_name: HashMap<&String, &NpmResolutionPackage> =
+    HashMap::with_capacity(package_partitions.packages.len());
+  for package in &package_partitions.packages {
+    if let Some(current_pkg) =
+      newest_packages_by_name.get_mut(&package.id.nv.name)
+    {
+      if current_pkg.id.nv.cmp(&package.id.nv) == Ordering::Less {
+        *current_pkg = package;
+      }
+    } else {
+      newest_packages_by_name.insert(&package.id.nv.name, package);
+    };
+
+    let package_folder_name =
+      get_package_folder_id_folder_name(&package.get_package_cache_folder_id());
+    let folder_path = deno_local_registry_dir.join(&package_folder_name);
+    let initialized_file = folder_path.join(".initialized");
+    if !cache
+      .cache_setting()
+      .should_use_for_npm_package(&package.id.nv.name)
+      || !initialized_file.exists()
+    {
+      // cache bust the dep from the dep setup cache so the symlinks
+      // are forced to be recreated
+      setup_cache.remove_dep(&package_folder_name);
+
+      let pb = progress_bar.clone();
+      let cache = cache.clone();
+      let registry_url = registry_url.clone();
+      let package = package.clone();
+      let handle = spawn(async move {
+        cache
+          .ensure_package(&package.id.nv, &package.dist, &registry_url)
+          .await?;
+        let pb_guard = pb.update_with_prompt(
+          ProgressMessagePrompt::Initialize,
+          &package.id.nv.to_string(),
+        );
+        let sub_node_modules = folder_path.join("node_modules");
+        let package_path =
+          join_package_name(&sub_node_modules, &package.id.nv.name);
+        fs::create_dir_all(&package_path)
+          .with_context(|| format!("Creating '{}'", folder_path.display()))?;
+        let cache_folder = cache
+          .package_folder_for_name_and_version(&package.id.nv, &registry_url);
+        // for now copy, but in the future consider hard linking
+        copy_dir_recursive(&cache_folder, &package_path)?;
+        // write out a file that indicates this folder has been initialized
+        fs::write(initialized_file, "")?;
+        // finally stop showing the progress bar
+        drop(pb_guard); // explicit for clarity
+        Ok(())
+      });
+      handles.push(handle);
+    }
+  }
+
+  let results = futures::future::join_all(handles).await;
+  for result in results {
+    result??; // surface the first error
+  }
+
+  // 2. Create any "copy" packages, which are used for peer dependencies
+  for package in &package_partitions.copy_packages {
+    let package_cache_folder_id = package.get_package_cache_folder_id();
+    let destination_path = deno_local_registry_dir
+      .join(get_package_folder_id_folder_name(&package_cache_folder_id));
+    let initialized_file = destination_path.join(".initialized");
+    if !initialized_file.exists() {
+      let sub_node_modules = destination_path.join("node_modules");
+      let package_path =
+        join_package_name(&sub_node_modules, &package.id.nv.name);
+      fs::create_dir_all(&package_path).with_context(|| {
+        format!("Creating '{}'", destination_path.display())
+      })?;
+      let source_path = join_package_name(
+        &deno_local_registry_dir
+          .join(get_package_folder_id_folder_name(
+            &package_cache_folder_id.with_no_count(),
+          ))
+          .join("node_modules"),
+        &package.id.nv.name,
+      );
+      hard_link_dir_recursive(&source_path, &package_path)?;
+      // write out a file that indicates this folder has been initialized
+      fs::write(initialized_file, "")?;
+    }
+  }
+
+  // 3. Symlink all the dependencies into the .deno directory.
+  //
+  // Symlink node_modules/.deno/<package_id>/node_modules/<dep_name> to
+  // node_modules/.deno/<dep_id>/node_modules/<dep_package_name>
+  for package in package_partitions.iter_all() {
+    let package_folder_name =
+      get_package_folder_id_folder_name(&package.get_package_cache_folder_id());
+    let sub_node_modules = deno_local_registry_dir
+      .join(&package_folder_name)
+      .join("node_modules");
+    let mut dep_setup_cache = setup_cache.with_dep(&package_folder_name);
+    for (name, dep_id) in &package.dependencies {
+      let dep_cache_folder_id = snapshot
+        .package_from_id(dep_id)
+        .unwrap()
+        .get_package_cache_folder_id();
+      let dep_folder_name =
+        get_package_folder_id_folder_name(&dep_cache_folder_id);
+      if dep_setup_cache.insert(name, &dep_folder_name) {
+        let dep_folder_path = join_package_name(
+          &deno_local_registry_dir
+            .join(dep_folder_name)
+            .join("node_modules"),
+          &dep_id.nv.name,
+        );
+        symlink_package_dir(
+          &dep_folder_path,
+          &join_package_name(&sub_node_modules, name),
+        )?;
+      }
+    }
+  }
+
+  // 4. Create all the top level packages in the node_modules folder, which are symlinks.
+  //
+  // Symlink node_modules/<package_name> to
+  // node_modules/.deno/<package_id>/node_modules/<package_name>
+  let mut found_names = HashSet::new();
+  let mut ids = snapshot.top_level_packages().collect::<Vec<_>>();
+  ids.sort_by(|a, b| b.cmp(a)); // create determinism and only include the latest version
+  for id in ids {
+    if !found_names.insert(&id.nv.name) {
+      continue; // skip, already handled
+    }
+    let package = snapshot.package_from_id(id).unwrap();
+    let target_folder_name =
+      get_package_folder_id_folder_name(&package.get_package_cache_folder_id());
+    if setup_cache.insert_root_symlink(&id.nv.name, &target_folder_name) {
+      let local_registry_package_path = join_package_name(
+        &deno_local_registry_dir
+          .join(target_folder_name)
+          .join("node_modules"),
+        &id.nv.name,
+      );
+
+      symlink_package_dir(
+        &local_registry_package_path,
+        &join_package_name(root_node_modules_dir_path, &id.nv.name),
+      )?;
+    }
+  }
+
+  // 5. Create a node_modules/.deno/node_modules/<package-name> directory with
+  // the remaining packages
+  for package in newest_packages_by_name.values() {
+    if !found_names.insert(&package.id.nv.name) {
+      continue; // skip, already handled
+    }
+
+    let target_folder_name =
+      get_package_folder_id_folder_name(&package.get_package_cache_folder_id());
+    if setup_cache.insert_deno_symlink(&package.id.nv.name, &target_folder_name)
+    {
+      let local_registry_package_path = join_package_name(
+        &deno_local_registry_dir
+          .join(target_folder_name)
+          .join("node_modules"),
+        &package.id.nv.name,
+      );
+
+      symlink_package_dir(
+        &local_registry_package_path,
+        &join_package_name(&deno_node_modules_dir, &package.id.nv.name),
+      )?;
+    }
+  }
+
+  setup_cache.save();
+  drop(single_process_lock);
+  drop(pb_clear_guard);
+
+  Ok(())
+}
+
+/// Represents a dependency at `node_modules/.deno/<package_id>/`
+struct SetupCacheDep<'a> {
+  previous: Option<&'a HashMap<String, String>>,
+  current: &'a mut HashMap<String, String>,
+}
+
+impl<'a> SetupCacheDep<'a> {
+  pub fn insert(&mut self, name: &str, target_folder_name: &str) -> bool {
+    self
+      .current
+      .insert(name.to_string(), target_folder_name.to_string());
+    if let Some(previous_target) = self.previous.and_then(|p| p.get(name)) {
+      previous_target != target_folder_name
+    } else {
+      true
+    }
+  }
+}
+
+#[derive(Debug, Default, Serialize, Deserialize, PartialEq, Eq)]
+struct SetupCacheData {
+  root_symlinks: HashMap<String, String>,
+  deno_symlinks: HashMap<String, String>,
+  dep_symlinks: HashMap<String, HashMap<String, String>>,
+}
+
+/// It is very slow to try to re-setup the symlinks each time, so this will
+/// cache what we've setup on the last run and only update what is necessary.
+/// Obviously this could lead to issues if the cache gets out of date with the
+/// file system, such as if the user manually deletes a symlink.
+struct SetupCache {
+  file_path: PathBuf,
+  previous: Option<SetupCacheData>,
+  current: SetupCacheData,
+}
+
+impl SetupCache {
+  pub fn load(file_path: PathBuf) -> Self {
+    let previous = std::fs::read(&file_path)
+      .ok()
+      .and_then(|data| bincode::deserialize(&data).ok());
+    Self {
+      file_path,
+      previous,
+      current: Default::default(),
+    }
+  }
+
+  pub fn save(&self) -> bool {
+    if let Some(previous) = &self.previous {
+      if previous == &self.current {
+        return false; // nothing to save
+      }
+    }
+
+    bincode::serialize(&self.current).ok().and_then(|data| {
+      atomic_write_file(&self.file_path, data, CACHE_PERM).ok()
+    });
+    true
+  }
+
+  /// Inserts and checks for the existence of a root symlink
+  /// at `node_modules/<package_name>` pointing to
+  /// `node_modules/.deno/<package_id>/`
+  pub fn insert_root_symlink(
+    &mut self,
+    name: &str,
+    target_folder_name: &str,
+  ) -> bool {
+    self
+      .current
+      .root_symlinks
+      .insert(name.to_string(), target_folder_name.to_string());
+    if let Some(previous_target) = self
+      .previous
+      .as_ref()
+      .and_then(|p| p.root_symlinks.get(name))
+    {
+      previous_target != target_folder_name
+    } else {
+      true
+    }
+  }
+
+  /// Inserts and checks for the existence of a symlink at
+  /// `node_modules/.deno/node_modules/<package_name>` pointing to
+  /// `node_modules/.deno/<package_id>/`
+  pub fn insert_deno_symlink(
+    &mut self,
+    name: &str,
+    target_folder_name: &str,
+  ) -> bool {
+    self
+      .current
+      .deno_symlinks
+      .insert(name.to_string(), target_folder_name.to_string());
+    if let Some(previous_target) = self
+      .previous
+      .as_ref()
+      .and_then(|p| p.deno_symlinks.get(name))
+    {
+      previous_target != target_folder_name
+    } else {
+      true
+    }
+  }
+
+  pub fn remove_dep(&mut self, parent_name: &str) {
+    if let Some(previous) = &mut self.previous {
+      previous.dep_symlinks.remove(parent_name);
+    }
+  }
+
+  pub fn with_dep(&mut self, parent_name: &str) -> SetupCacheDep<'_> {
+    SetupCacheDep {
+      previous: self
+        .previous
+        .as_ref()
+        .and_then(|p| p.dep_symlinks.get(parent_name)),
+      current: self
+        .current
+        .dep_symlinks
+        .entry(parent_name.to_string())
+        .or_default(),
+    }
+  }
+}
+
+fn get_package_folder_id_folder_name(
+  folder_id: &NpmPackageCacheFolderId,
+) -> String {
+  let copy_str = if folder_id.copy_index == 0 {
+    "".to_string()
+  } else {
+    format!("_{}", folder_id.copy_index)
+  };
+  let nv = &folder_id.nv;
+  let name = if nv.name.to_lowercase() == nv.name {
+    Cow::Borrowed(&nv.name)
+  } else {
+    Cow::Owned(format!("_{}", mixed_case_package_name_encode(&nv.name)))
+  };
+  format!("{}@{}{}", name, nv.version, copy_str).replace('/', "+")
+}
+
+fn get_package_folder_id_from_folder_name(
+  folder_name: &str,
+) -> Option<NpmPackageCacheFolderId> {
+  let folder_name = folder_name.replace('+', "/");
+  let (name, ending) = folder_name.rsplit_once('@')?;
+  let name = if let Some(encoded_name) = name.strip_prefix('_') {
+    mixed_case_package_name_decode(encoded_name)?
+  } else {
+    name.to_string()
+  };
+  let (raw_version, copy_index) = match ending.split_once('_') {
+    Some((raw_version, copy_index)) => {
+      let copy_index = copy_index.parse::<u8>().ok()?;
+      (raw_version, copy_index)
+    }
+    None => (ending, 0),
+  };
+  let version = deno_semver::Version::parse_from_npm(raw_version).ok()?;
+  Some(NpmPackageCacheFolderId {
+    nv: PackageNv { name, version },
+    copy_index,
+  })
+}
+
+fn symlink_package_dir(
+  old_path: &Path,
+  new_path: &Path,
+) -> Result<(), AnyError> {
+  let new_parent = new_path.parent().unwrap();
+  if new_parent.file_name().unwrap() != "node_modules" {
+    // create the parent folder that will contain the symlink
+    fs::create_dir_all(new_parent)
+      .with_context(|| format!("Creating '{}'", new_parent.display()))?;
+  }
+
+  // need to delete the previous symlink before creating a new one
+  let _ignore = fs::remove_dir_all(new_path);
+
+  #[cfg(windows)]
+  return junction_or_symlink_dir(old_path, new_path);
+  #[cfg(not(windows))]
+  symlink_dir(old_path, new_path)
+}
+
+#[cfg(windows)]
+fn junction_or_symlink_dir(
+  old_path: &Path,
+  new_path: &Path,
+) -> Result<(), AnyError> {
+  // Use junctions because they're supported on ntfs file systems without
+  // needing to elevate privileges on Windows
+
+  match junction::create(old_path, new_path) {
+    Ok(()) => Ok(()),
+    Err(junction_err) => {
+      if cfg!(debug) {
+        // When running the tests, junctions should be created, but if not then
+        // surface this error.
+        log::warn!("Error creating junction. {:#}", junction_err);
+      }
+
+      match symlink_dir(old_path, new_path) {
+        Ok(()) => Ok(()),
+        Err(symlink_err) => bail!(
+          concat!(
+            "Failed creating junction and fallback symlink in node_modules folder.\n\n",
+            "{:#}\n\n{:#}",
+          ),
+          junction_err,
+          symlink_err,
+        ),
+      }
+    }
+  }
+}
+
+fn join_package_name(path: &Path, package_name: &str) -> PathBuf {
+  let mut path = path.to_path_buf();
+  // ensure backslashes are used on windows
+  for part in package_name.split('/') {
+    path = path.join(part);
+  }
+  path
+}
+
+#[cfg(test)]
+mod test {
+  use deno_npm::NpmPackageCacheFolderId;
+  use deno_semver::package::PackageNv;
+  use test_util::TempDir;
+
+  use super::*;
+
+  #[test]
+  fn test_get_package_folder_id_folder_name() {
+    let cases = vec![
+      (
+        NpmPackageCacheFolderId {
+          nv: PackageNv::from_str("@types/foo@1.2.3").unwrap(),
+          copy_index: 1,
+        },
+        "@types+foo@1.2.3_1".to_string(),
+      ),
+      (
+        NpmPackageCacheFolderId {
+          nv: PackageNv::from_str("JSON@3.2.1").unwrap(),
+          copy_index: 0,
+        },
+        "_jjju6tq@3.2.1".to_string(),
+      ),
+    ];
+    for (input, output) in cases {
+      assert_eq!(get_package_folder_id_folder_name(&input), output);
+      let folder_id = get_package_folder_id_from_folder_name(&output).unwrap();
+      assert_eq!(folder_id, input);
+    }
+  }
+
+  #[test]
+  fn test_setup_cache() {
+    let temp_dir = TempDir::new();
+    let cache_bin_path = temp_dir.path().join("cache.bin").to_path_buf();
+    let mut cache = SetupCache::load(cache_bin_path.clone());
+    assert!(cache.insert_deno_symlink("package-a", "package-a@1.0.0"));
+    assert!(cache.insert_root_symlink("package-a", "package-a@1.0.0"));
+    assert!(cache
+      .with_dep("package-a")
+      .insert("package-b", "package-b@1.0.0"));
+    assert!(cache.save());
+
+    let mut cache = SetupCache::load(cache_bin_path.clone());
+    assert!(!cache.insert_deno_symlink("package-a", "package-a@1.0.0"));
+    assert!(!cache.insert_root_symlink("package-a", "package-a@1.0.0"));
+    assert!(!cache
+      .with_dep("package-a")
+      .insert("package-b", "package-b@1.0.0"));
+    assert!(!cache.save());
+    assert!(cache.insert_root_symlink("package-b", "package-b@0.2.0"));
+    assert!(cache.save());
+
+    let mut cache = SetupCache::load(cache_bin_path);
+    cache.remove_dep("package-a");
+    assert!(cache
+      .with_dep("package-a")
+      .insert("package-b", "package-b@1.0.0"));
+  }
+}