diff --git a/Cargo.lock b/Cargo.lock
index 308fad0d7..b8ef47bda 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1397,6 +1397,7 @@ dependencies = [
  "serde",
  "serde_json",
  "static_assertions",
+ "vfs",
 ]
 
 [[package]]
@@ -2265,6 +2266,12 @@ version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
 
+[[package]]
+name = "vfs"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ded573c92d7b32013bdab82676be59f56106895e837504568f32804980ec7868"
+
 [[package]]
 name = "walkdir"
 version = "2.3.3"
diff --git a/crates/oxc_resolver/Cargo.toml b/crates/oxc_resolver/Cargo.toml
index 7e76171d6..1304341af 100644
--- a/crates/oxc_resolver/Cargo.toml
+++ b/crates/oxc_resolver/Cargo.toml
@@ -18,6 +18,7 @@ serde_json = { workspace = true }
 [dev-dependencies]
 static_assertions = { workspace = true }
 criterion         = { workspace = true }
+vfs = "0.9.0"
 
 [[bench]]
 name    = "resolver"
diff --git a/crates/oxc_resolver/README.md b/crates/oxc_resolver/README.md
index 0fbc8ff1c..c81bc1663 100644
--- a/crates/oxc_resolver/README.md
+++ b/crates/oxc_resolver/README.md
@@ -20,7 +20,7 @@
 |      | exportsFields    | ["exports"]                 | A list of exports fields in description files                                                                                                             |
 |  ✅  | extensions       | [".js", ".json", ".node"]   | A list of extensions which should be tried for files                                                                                                      |
 |      | fallback         | []                          | Same as `alias`, but only used if default resolving fails                                                                                                 |
-|      | fileSystem       |                             | The file system which should be used                                                                                                                      |
+|  ✅  | fileSystem       |                             | The file system which should be used                                                                                                                      |
 |      | fullySpecified   | false                       | Request passed to resolve is already fully specified and extensions or main files are not resolved for it (they are still resolved for internal requests) |
 |      | mainFields       | ["main"]                    | A list of main fields in description files                                                                                                                |
 |  ✅  | mainFiles        | ["index"]                   | A list of main files in directories                                                                                                                       |
diff --git a/crates/oxc_resolver/src/cache.rs b/crates/oxc_resolver/src/cache.rs
new file mode 100644
index 000000000..b8151640d
--- /dev/null
+++ b/crates/oxc_resolver/src/cache.rs
@@ -0,0 +1,56 @@
+use std::{path::Path, sync::Arc};
+
+use dashmap::DashMap;
+
+use crate::{package_json::PackageJson, FileMetadata, FileSystem, ResolveError};
+
+pub struct Cache<Fs> {
+    fs: Fs,
+    cache: DashMap<Box<Path>, Option<FileMetadata>>,
+    package_json_cache: DashMap<Box<Path>, Result<Arc<PackageJson>, ResolveError>>,
+}
+
+impl<Fs: FileSystem> Default for Cache<Fs> {
+    fn default() -> Self {
+        Self { fs: Fs::default(), cache: DashMap::new(), package_json_cache: DashMap::new() }
+    }
+}
+
+impl<Fs: FileSystem> Cache<Fs> {
+    pub fn new(fs: Fs) -> Self {
+        Self { fs, ..Self::default() }
+    }
+
+    fn metadata_cached(&self, path: &Path) -> Option<FileMetadata> {
+        if let Some(result) = self.cache.get(path) {
+            return *result;
+        }
+        let file_metadata = self.fs.metadata(path).ok();
+        self.cache.insert(path.to_path_buf().into_boxed_path(), file_metadata);
+        file_metadata
+    }
+
+    pub fn is_file(&self, path: &Path) -> bool {
+        self.metadata_cached(path).is_some_and(|m| m.is_file)
+    }
+
+    /// # Errors
+    ///
+    /// * [ResolveError::JSONError]
+    ///
+    /// # Panics
+    ///
+    /// * Failed to read the file (TODO: remove this)
+    pub fn read_package_json(&self, path: &Path) -> Result<Arc<PackageJson>, ResolveError> {
+        if let Some(result) = self.package_json_cache.get(path) {
+            return result.value().clone();
+        }
+        // TODO: handle file read error
+        let package_json_string = self.fs.read_to_string(path).unwrap();
+        let result = PackageJson::parse(path.to_path_buf(), &package_json_string)
+            .map(Arc::new)
+            .map_err(|error| ResolveError::from_serde_json_error(path.to_path_buf(), &error));
+        self.package_json_cache.insert(path.to_path_buf().into_boxed_path(), result.clone());
+        result
+    }
+}
diff --git a/crates/oxc_resolver/src/file_system.rs b/crates/oxc_resolver/src/file_system.rs
index c0c951d8a..527dfc952 100644
--- a/crates/oxc_resolver/src/file_system.rs
+++ b/crates/oxc_resolver/src/file_system.rs
@@ -1,46 +1,38 @@
-use std::{fs, path::Path, sync::Arc};
+use std::{fs, io, path::Path};
 
-use dashmap::DashMap;
+pub trait FileSystem: Default + Send + Sync {
+    /// # Errors
+    ///
+    /// * Any [io::Error]
+    fn read_to_string<P: AsRef<Path>>(&self, path: P) -> io::Result<String>;
 
-use crate::{package_json::PackageJson, ResolveError};
+    /// # Errors
+    ///
+    /// * Any [io::Error]
+    fn metadata<P: AsRef<Path>>(&self, path: P) -> io::Result<FileMetadata>;
+}
 
 #[derive(Debug, Clone, Copy)]
 pub struct FileMetadata {
-    is_file: bool,
+    pub(crate) is_file: bool,
 }
 
-/// [File System](https://doc.rust-lang.org/stable/std/fs/) with caching
+impl FileMetadata {
+    pub fn new(is_file: bool) -> Self {
+        Self { is_file }
+    }
+}
+
+/// Operating System
 #[derive(Default)]
-pub struct FileSystem {
-    cache: DashMap<Box<Path>, Option<FileMetadata>>,
-    package_json_cache: DashMap<Box<Path>, Result<Arc<PackageJson>, ResolveError>>,
-}
+pub struct FileSystemOs;
 
-impl FileSystem {
-    /// <https://doc.rust-lang.org/stable/std/fs/fn.metadata.html>
-    pub fn metadata(&self, path: &Path) -> Option<FileMetadata> {
-        if let Some(result) = self.cache.get(path) {
-            return *result;
-        }
-        let file_metadata =
-            fs::metadata(path).ok().map(|metadata| FileMetadata { is_file: metadata.is_file() });
-        self.cache.insert(path.to_path_buf().into_boxed_path(), file_metadata);
-        file_metadata
+impl FileSystem for FileSystemOs {
+    fn read_to_string<P: AsRef<Path>>(&self, path: P) -> io::Result<String> {
+        fs::read_to_string(path)
     }
 
-    pub fn is_file(&self, path: &Path) -> bool {
-        self.metadata(path).is_some_and(|m| m.is_file)
-    }
-
-    pub fn read_package_json(&self, path: &Path) -> Result<Arc<PackageJson>, ResolveError> {
-        if let Some(result) = self.package_json_cache.get(path) {
-            return result.value().clone();
-        }
-        let package_json_string = fs::read_to_string(path).unwrap();
-        let result = PackageJson::parse(path.to_path_buf(), &package_json_string)
-            .map(Arc::new)
-            .map_err(|error| ResolveError::from_serde_json_error(path.to_path_buf(), &error));
-        self.package_json_cache.insert(path.to_path_buf().into_boxed_path(), result.clone());
-        result
+    fn metadata<P: AsRef<Path>>(&self, path: P) -> io::Result<FileMetadata> {
+        fs::metadata(path).map(|metadata| FileMetadata { is_file: metadata.is_file() })
     }
 }
diff --git a/crates/oxc_resolver/src/lib.rs b/crates/oxc_resolver/src/lib.rs
index fe659dea0..ddd03901d 100644
--- a/crates/oxc_resolver/src/lib.rs
+++ b/crates/oxc_resolver/src/lib.rs
@@ -6,12 +6,14 @@
 //! * Algorithm adapted from [Node.js Module Resolution Algorithm](https://nodejs.org/api/modules.html#all-together) and [cjs loader](https://github.com/nodejs/node/blob/main/lib/internal/modules/cjs/loader.js)
 //! * Some code adapted from [parcel-resolver](https://github.com/parcel-bundler/parcel/blob/v2/packages/utils/node-resolver-rs)
 
+mod cache;
 mod error;
 mod file_system;
 mod options;
 mod package_json;
 mod path;
 mod request;
+mod resolution;
 
 use std::{
     ffi::OsStr,
@@ -19,11 +21,13 @@ use std::{
 };
 
 pub use crate::{
+    cache::Cache,
     error::{JSONError, ResolveError},
+    file_system::{FileMetadata, FileSystem, FileSystemOs},
     options::ResolveOptions,
+    resolution::Resolution,
 };
 use crate::{
-    file_system::FileSystem,
     path::PathUtil,
     request::{Request, RequestPath},
 };
@@ -31,49 +35,27 @@ use crate::{
 pub type ResolveResult = Result<Resolution, ResolveError>;
 type ResolveState = Result<Option<PathBuf>, ResolveError>;
 
-#[derive(Debug, Clone, Eq, PartialEq)]
-pub struct Resolution {
-    path: PathBuf,
+/// Resolver with the current operating system as the file system
+pub type Resolver = ResolverGeneric<FileSystemOs>;
 
-    /// path query `?query`, contains `?`.
-    query: Option<String>,
-
-    /// path fragment `#query`, contains `#`.
-    fragment: Option<String>,
-}
-
-impl Resolution {
-    pub fn path(&self) -> &Path {
-        &self.path
-    }
-
-    pub fn into_path_buf(self) -> PathBuf {
-        self.path
-    }
-
-    pub fn query(&self) -> Option<&str> {
-        self.query.as_deref()
-    }
-
-    pub fn fragment(&self) -> Option<&str> {
-        self.fragment.as_deref()
-    }
-}
-
-pub struct Resolver {
+pub struct ResolverGeneric<Fs> {
     options: ResolveOptions,
-    fs: FileSystem,
+    cache: Cache<Fs>,
 }
 
-impl Default for Resolver {
+impl<Fs: FileSystem> Default for ResolverGeneric<Fs> {
     fn default() -> Self {
         Self::new(ResolveOptions::default())
     }
 }
 
-impl Resolver {
+impl<Fs: FileSystem> ResolverGeneric<Fs> {
     pub fn new(options: ResolveOptions) -> Self {
-        Self { options: options.sanitize(), fs: FileSystem::default() }
+        Self { options: options.sanitize(), cache: Cache::default() }
+    }
+
+    pub fn new_with_file_system(options: ResolveOptions, file_system: Fs) -> Self {
+        Self { cache: Cache::new(file_system), ..Self::new(options) }
     }
 
     /// Resolve `request` at `path`
@@ -160,7 +142,7 @@ impl Resolver {
         }
 
         // 1. If X is a file, load X as its file extension format. STOP
-        if self.fs.is_file(path) {
+        if self.cache.is_file(path) {
             return Ok(Some(path.to_path_buf()));
         }
         // 2. If X.js is a file, load X.js as JavaScript text. STOP
@@ -168,7 +150,7 @@ impl Resolver {
         // 4. If X.node is a file, load X.node as binary addon. STOP
         for extension in &self.options.extensions {
             let path_with_extension = path.with_extension(extension);
-            if self.fs.is_file(&path_with_extension) {
+            if self.cache.is_file(&path_with_extension) {
                 return Ok(Some(path_with_extension));
             }
         }
@@ -182,7 +164,7 @@ impl Resolver {
         // 3. If X/index.node is a file, load X/index.node as binary addon. STOP
         for extension in &self.options.extensions {
             let index_path = path.join("index").with_extension(extension);
-            if self.fs.is_file(&index_path) {
+            if self.cache.is_file(&index_path) {
                 return Ok(Some(index_path));
             }
         }
@@ -192,9 +174,9 @@ impl Resolver {
     fn load_as_directory(&self, path: &Path) -> ResolveState {
         // 1. If X/package.json is a file,
         let package_json_path = path.join("package.json");
-        if self.fs.is_file(&package_json_path) {
+        if self.cache.is_file(&package_json_path) {
             // a. Parse X/package.json, and look for "main" field.
-            let package_json = self.fs.read_package_json(&package_json_path)?;
+            let package_json = self.cache.read_package_json(&package_json_path)?;
             // b. If "main" is a falsy value, GOTO 2.
             if let Some(main_field) = &package_json.main {
                 // c. let M = X + (json main field)
@@ -251,8 +233,8 @@ impl Resolver {
     fn load_package_self(&self, path: &Path, request_str: &str) -> ResolveState {
         for dir in path.ancestors() {
             let package_json_path = dir.join("package.json");
-            if self.fs.is_file(&package_json_path) {
-                let package_json = self.fs.read_package_json(&package_json_path)?;
+            if self.cache.is_file(&package_json_path) {
+                let package_json = self.cache.read_package_json(&package_json_path)?;
                 if let Some(request_str) =
                     package_json.resolve_request(path, request_str, &self.options.extensions)?
                 {
@@ -282,7 +264,7 @@ impl Resolver {
         };
         for extension in extensions {
             let path_with_extension = path.with_extension(extension);
-            if self.fs.is_file(&path_with_extension) {
+            if self.cache.is_file(&path_with_extension) {
                 return Ok(Some(path_with_extension));
             }
         }
diff --git a/crates/oxc_resolver/src/resolution.rs b/crates/oxc_resolver/src/resolution.rs
new file mode 100644
index 000000000..56b599eb2
--- /dev/null
+++ b/crates/oxc_resolver/src/resolution.rs
@@ -0,0 +1,30 @@
+use std::path::{Path, PathBuf};
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct Resolution {
+    pub(crate) path: PathBuf,
+
+    /// path query `?query`, contains `?`.
+    pub(crate) query: Option<String>,
+
+    /// path fragment `#query`, contains `#`.
+    pub(crate) fragment: Option<String>,
+}
+
+impl Resolution {
+    pub fn path(&self) -> &Path {
+        &self.path
+    }
+
+    pub fn into_path_buf(self) -> PathBuf {
+        self.path
+    }
+
+    pub fn query(&self) -> Option<&str> {
+        self.query.as_deref()
+    }
+
+    pub fn fragment(&self) -> Option<&str> {
+        self.fragment.as_deref()
+    }
+}
diff --git a/crates/oxc_resolver/tests/enhanced_resolve/test/alias.rs b/crates/oxc_resolver/tests/enhanced_resolve/test/alias.rs
new file mode 100644
index 000000000..9d870c52b
--- /dev/null
+++ b/crates/oxc_resolver/tests/enhanced_resolve/test/alias.rs
@@ -0,0 +1,27 @@
+//! <https://github.com/webpack/enhanced-resolve/blob/main/test/alias.test.js>
+
+use oxc_resolver::{ResolveOptions, ResolverGeneric};
+
+use crate::MemoryFS;
+
+#[test]
+fn alias() {
+    let file_system = MemoryFS::new(&[
+        ("/a/index", ""),
+        ("/a/dir/index", ""),
+        ("/recursive/index", ""),
+        ("/recursive/dir/index", ""),
+        ("/b/index", ""),
+        ("/b/dir/index", ""),
+        ("/c/index", ""),
+        ("/c/dir/index", ""),
+        ("/d/index.js", ""),
+        ("/d/dir/.empty", ""),
+        ("/e/index", ""),
+        ("/e/anotherDir/index", ""),
+        ("/e/dir/file", ""),
+    ]);
+    let options = ResolveOptions::default();
+    let resolver = ResolverGeneric::<MemoryFS>::new_with_file_system(options, file_system);
+    assert!(resolver.resolve("/a/index", ".").is_ok());
+}
diff --git a/crates/oxc_resolver/tests/enhanced_resolve/test/mod.rs b/crates/oxc_resolver/tests/enhanced_resolve/test/mod.rs
index 21b53e972..70aa8c438 100644
--- a/crates/oxc_resolver/tests/enhanced_resolve/test/mod.rs
+++ b/crates/oxc_resolver/tests/enhanced_resolve/test/mod.rs
@@ -1,3 +1,4 @@
+mod alias;
 mod browser_field;
 mod extension_alias;
 mod extensions;
diff --git a/crates/oxc_resolver/tests/memory_fs.rs b/crates/oxc_resolver/tests/memory_fs.rs
new file mode 100644
index 000000000..8997b2ca7
--- /dev/null
+++ b/crates/oxc_resolver/tests/memory_fs.rs
@@ -0,0 +1,60 @@
+use std::{io, path::Path};
+
+use oxc_resolver::{FileMetadata, FileSystem};
+
+pub struct MemoryFS {
+    fs: vfs::MemoryFS,
+}
+
+impl Default for MemoryFS {
+    fn default() -> Self {
+        let fs = vfs::MemoryFS::new();
+        Self { fs }
+    }
+}
+
+impl MemoryFS {
+    /// # Panics
+    ///
+    /// * Fails to create directory
+    /// * Fails to write file
+    pub fn new(data: &[(&'static str, &'static str)]) -> Self {
+        use vfs::FileSystem;
+        let fs = vfs::MemoryFS::default();
+        for (path, string) in data {
+            // Create all parent directories
+            for path in Path::new(path).ancestors().collect::<Vec<_>>().iter().rev() {
+                let path = path.to_string_lossy();
+                if !fs.exists(path.as_ref()).unwrap() {
+                    fs.create_dir(path.as_ref()).unwrap();
+                }
+            }
+            let mut file = fs.create_file(path).unwrap();
+            file.write_all(string.as_bytes()).unwrap();
+        }
+        Self { fs }
+    }
+}
+
+impl FileSystem for MemoryFS {
+    fn read_to_string<P: AsRef<Path>>(&self, path: P) -> io::Result<String> {
+        use vfs::FileSystem;
+        let mut file = self
+            .fs
+            .open_file(path.as_ref().to_string_lossy().as_ref())
+            .map_err(|err| io::Error::new(io::ErrorKind::NotFound, err))?;
+        let mut buffer = String::new();
+        file.read_to_string(&mut buffer).unwrap();
+        Ok(buffer)
+    }
+
+    fn metadata<P: AsRef<Path>>(&self, path: P) -> io::Result<FileMetadata> {
+        use vfs::FileSystem;
+        let metadata = self
+            .fs
+            .metadata(path.as_ref().to_string_lossy().as_ref())
+            .map_err(|err| io::Error::new(io::ErrorKind::NotFound, err))?;
+        let is_file = metadata.file_type == vfs::VfsFileType::File;
+        Ok(FileMetadata::new(is_file))
+    }
+}
diff --git a/crates/oxc_resolver/tests/mod.rs b/crates/oxc_resolver/tests/mod.rs
index 3f2f0c7a1..8d7d45340 100644
--- a/crates/oxc_resolver/tests/mod.rs
+++ b/crates/oxc_resolver/tests/mod.rs
@@ -1,7 +1,9 @@
 mod enhanced_resolve;
+mod memory_fs;
 
 use std::{env, sync::Arc, thread};
 
+pub(crate) use memory_fs::MemoryFS;
 use oxc_resolver::Resolver;
 
 #[test]