diff --git a/crates/els/server.rs b/crates/els/server.rs
index 455af0ab..24d14ecc 100644
--- a/crates/els/server.rs
+++ b/crates/els/server.rs
@@ -27,7 +27,7 @@ use erg_compiler::module::{SharedCompilerResource, SharedModuleGraph, SharedModu
 use erg_compiler::ty::HasType;
 
 pub use molc::RedirectableStdout;
-use molc::{DummyClient, LangServer};
+use molc::{FakeClient, LangServer};
 
 use lsp_types::request::{
     CallHierarchyIncomingCalls, CallHierarchyOutgoingCalls, CallHierarchyPrepare,
@@ -298,9 +298,9 @@ impl LangServer for Server {
 
 impl Server {
     #[allow(unused)]
-    pub fn bind_dummy_client() -> DummyClient<Server> {
+    pub fn bind_fake_client() -> FakeClient<Server> {
         let (sender, receiver) = std::sync::mpsc::channel();
-        DummyClient::new(Server::new(ErgConfig::default(), Some(sender)), receiver)
+        FakeClient::new(Server::new(ErgConfig::default(), Some(sender)), receiver)
     }
 }
 
diff --git a/crates/els/tests/test.rs b/crates/els/tests/test.rs
index 582aba6e..6d39e657 100644
--- a/crates/els/tests/test.rs
+++ b/crates/els/tests/test.rs
@@ -13,7 +13,7 @@ use molc::{add_char, oneline_range};
 
 #[test]
 fn test_open() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = Server::bind_dummy_client();
+    let mut client = Server::bind_fake_client();
     client.request_initialize()?;
     client.notify_open(FILE_A)?;
     client.wait_messages(3)?;
@@ -25,7 +25,7 @@ fn test_open() -> Result<(), Box<dyn std::error::Error>> {
 
 #[test]
 fn test_completion() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = Server::bind_dummy_client();
+    let mut client = Server::bind_fake_client();
     client.request_initialize()?;
     let uri = NormalizedUrl::from_file_path(Path::new(FILE_A).canonicalize()?)?;
     client.notify_open(FILE_A)?;
@@ -43,7 +43,7 @@ fn test_completion() -> Result<(), Box<dyn std::error::Error>> {
 
 #[test]
 fn test_neighbor_completion() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = Server::bind_dummy_client();
+    let mut client = Server::bind_fake_client();
     client.request_initialize()?;
     let uri = NormalizedUrl::from_file_path(Path::new(FILE_A).canonicalize()?)?;
     client.notify_open(FILE_A)?;
@@ -62,7 +62,7 @@ fn test_neighbor_completion() -> Result<(), Box<dyn std::error::Error>> {
 
 #[test]
 fn test_rename() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = Server::bind_dummy_client();
+    let mut client = Server::bind_fake_client();
     client.request_initialize()?;
     let uri = NormalizedUrl::from_file_path(Path::new(FILE_A).canonicalize()?)?;
     client.notify_open(FILE_A)?;
@@ -77,7 +77,7 @@ fn test_rename() -> Result<(), Box<dyn std::error::Error>> {
 
 #[test]
 fn test_signature_help() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = Server::bind_dummy_client();
+    let mut client = Server::bind_fake_client();
     client.request_initialize()?;
     let uri = NormalizedUrl::from_file_path(Path::new(FILE_A).canonicalize()?)?;
     client.notify_open(FILE_A)?;
@@ -95,7 +95,7 @@ fn test_signature_help() -> Result<(), Box<dyn std::error::Error>> {
 
 #[test]
 fn test_hover() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = Server::bind_dummy_client();
+    let mut client = Server::bind_fake_client();
     client.request_initialize()?;
     let uri = NormalizedUrl::from_file_path(Path::new(FILE_A).canonicalize()?)?;
     client.notify_open(FILE_A)?;
@@ -120,7 +120,7 @@ fn test_hover() -> Result<(), Box<dyn std::error::Error>> {
 
 #[test]
 fn test_references() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = Server::bind_dummy_client();
+    let mut client = Server::bind_fake_client();
     client.request_initialize()?;
     let uri = NormalizedUrl::from_file_path(Path::new(FILE_A).canonicalize()?)?;
     client.notify_open(FILE_A)?;
@@ -132,7 +132,7 @@ fn test_references() -> Result<(), Box<dyn std::error::Error>> {
 
 #[test]
 fn test_goto_definition() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = Server::bind_dummy_client();
+    let mut client = Server::bind_fake_client();
     client.request_initialize()?;
     let uri = NormalizedUrl::from_file_path(Path::new(FILE_A).canonicalize()?)?;
     client.notify_open(FILE_A)?;
@@ -147,7 +147,7 @@ fn test_goto_definition() -> Result<(), Box<dyn std::error::Error>> {
 
 #[test]
 fn test_folding_range() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = Server::bind_dummy_client();
+    let mut client = Server::bind_fake_client();
     client.request_initialize()?;
     let uri = NormalizedUrl::from_file_path(Path::new(FILE_IMPORTS).canonicalize()?)?;
     client.notify_open(FILE_IMPORTS)?;
@@ -168,7 +168,7 @@ fn test_folding_range() -> Result<(), Box<dyn std::error::Error>> {
 
 #[test]
 fn test_document_symbol() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = Server::bind_dummy_client();
+    let mut client = Server::bind_fake_client();
     client.request_initialize()?;
     let uri = NormalizedUrl::from_file_path(Path::new(FILE_A).canonicalize()?)?;
     client.notify_open(FILE_A)?;
diff --git a/crates/molc/README.md b/crates/molc/README.md
index 6a74012e..2c74106a 100644
--- a/crates/molc/README.md
+++ b/crates/molc/README.md
@@ -1,6 +1,6 @@
 # `molc`
 
-`molc` is a mock language client for testing language servers.
+`molc` is a mock (fake) language client for testing language servers.
 
 ## Usage
 
@@ -9,7 +9,7 @@ You can see specific examples of molc use in [ELS](https://github.com/erg-lang/e
 ```rust
 use lsp_types::{Url, Value};
 
-use molc::{DummyClient, LangServer, RedirectableStdout};
+use molc::{FakeClient, LangServer, RedirectableStdout};
 use molc::oneline_range;
 
 pub struct Server {
@@ -30,7 +30,7 @@ impl RedirectableStdout for Server {
 }
 
 impl Server {
-    fn bind_dummy_client() -> DummyClient<Self> {
+    fn bind_fake_client() -> FakeClient<Self> {
         // The server should send responses to this channel at least during testing.
         let (sender, receiver) = std::sync::mpsc::channel();
         DummyClient::new(
@@ -57,7 +57,7 @@ impl Server {
 
 #[test]
 fn test_references() -> Result<(), Box<dyn std::error::Error>> {
-    let mut client = Server::bind_dummy_client();
+    let mut client = Server::bind_fake_client();
     client.request_initialize()?;
     let uri = Url::from_file_path(Path::new(FILE_A).canonicalize()?).unwrap();
     client.notify_open(FILE_A)?;
diff --git a/crates/molc/src/lib.rs b/crates/molc/src/lib.rs
index 4047048a..4477f485 100644
--- a/crates/molc/src/lib.rs
+++ b/crates/molc/src/lib.rs
@@ -133,7 +133,7 @@ pub trait LangServer {
     fn dispatch(&mut self, msg: impl Into<Value>) -> Result<()>;
 }
 
-pub struct DummyClient<LS: LangServer> {
+pub struct FakeClient<LS: LangServer> {
     server: LS,
     receiver: std::sync::mpsc::Receiver<Value>,
     server_capas: Option<ServerCapabilities>,
@@ -144,10 +144,10 @@ pub struct DummyClient<LS: LangServer> {
     req_id: i64,
 }
 
-impl<LS: LangServer> DummyClient<LS> {
+impl<LS: LangServer> FakeClient<LS> {
     /// The server should send responses to the channel at least during testing.
     pub fn new(server: LS, receiver: std::sync::mpsc::Receiver<Value>) -> Self {
-        DummyClient {
+        FakeClient {
             receiver,
             responses: Vec::new(),
             ver: 0,