[ty] Move server tests as integration tests (#19522)

## Summary

Reference:
https://github.com/astral-sh/ruff/pull/19391#discussion_r2222780892

Cargo.lock

@@ -4344,6 +4344,7 @@ dependencies = [
  "ty_ide",
  "ty_project",
  "ty_python_semantic",
+ "ty_server",
  "ty_vendored",
 ]
 

crates/ty_server/Cargo.toml

@@ -38,11 +38,16 @@ tracing = { workspace = true }
 tracing-subscriber = { workspace = true, features = ["chrono"] }
 
 [dev-dependencies]
+ty_server = { workspace = true, features = ["testing"] }
+
 dunce = { workspace = true }
 insta = { workspace = true, features = ["filters", "json"] }
 regex = { workspace = true }
 tempfile = { workspace = true }
 
+[features]
+testing = []
+
 [target.'cfg(target_vendor = "apple")'.dependencies]
 libc = { workspace = true }
 

crates/ty_server/src/lib.rs

@@ -4,7 +4,9 @@ use anyhow::Context;
 use lsp_server::Connection;
 use ruff_db::system::{OsSystem, SystemPathBuf};
 
-use crate::server::Server;
+pub use crate::logging::{LogLevel, init_logging};
+pub use crate::server::Server;
+pub use crate::session::ClientOptions;
 pub use document::{NotebookDocument, PositionEncoding, TextDocument};
 pub(crate) use session::{DocumentQuery, Session};
 
@@ -14,9 +16,6 @@ mod server;
 mod session;
 mod system;
 
-#[cfg(test)]
-pub mod test;
-
 pub(crate) const SERVER_NAME: &str = "ty";
 pub(crate) const DIAGNOSTIC_NAME: &str = "ty";
 

crates/ty_server/src/logging.rs

@@ -14,7 +14,7 @@ use tracing_subscriber::fmt::time::ChronoLocal;
 use tracing_subscriber::fmt::writer::BoxMakeWriter;
 use tracing_subscriber::layer::SubscriberExt;
 
-pub(crate) fn init_logging(log_level: LogLevel, log_file: Option<&SystemPath>) {
+pub fn init_logging(log_level: LogLevel, log_file: Option<&SystemPath>) {
     let log_file = log_file
         .map(|path| {
             // this expands `logFile` so that tildes and environment variables
@@ -66,7 +66,7 @@ pub(crate) fn init_logging(log_level: LogLevel, log_file: Option<&SystemPath>) {
 /// The default log level is `info`.
 #[derive(Clone, Copy, Debug, Deserialize, Default, PartialEq, Eq, PartialOrd, Ord)]
 #[serde(rename_all = "lowercase")]
-pub(crate) enum LogLevel {
+pub enum LogLevel {
     Error,
     Warn,
     #[default]

crates/ty_server/src/server.rs

@@ -26,7 +26,7 @@ pub(crate) use api::publish_settings_diagnostics;
 pub(crate) use main_loop::{Action, ConnectionSender, Event, MainLoopReceiver, MainLoopSender};
 pub(crate) type Result<T> = std::result::Result<T, api::Error>;
 
-pub(crate) struct Server {
+pub struct Server {
     connection: Connection,
     client_capabilities: ClientCapabilities,
     worker_threads: NonZeroUsize,
@@ -36,7 +36,7 @@ pub(crate) struct Server {
 }
 
 impl Server {
-    pub(crate) fn new(
+    pub fn new(
         worker_threads: NonZeroUsize,
         connection: Connection,
         native_system: Arc<dyn System + 'static + Send + Sync + RefUnwindSafe>,
@@ -161,7 +161,7 @@ impl Server {
         })
     }
 
-    pub(crate) fn run(mut self) -> crate::Result<()> {
+    pub fn run(mut self) -> crate::Result<()> {
         let client = Client::new(
             self.main_loop_sender.clone(),
             self.connection.sender.clone(),
@@ -302,89 +302,3 @@ impl Drop for ServerPanicHookHandler {
         }
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use anyhow::Result;
-    use lsp_types::notification::PublishDiagnostics;
-    use ruff_db::system::SystemPath;
-
-    use crate::session::ClientOptions;
-    use crate::test::TestServerBuilder;
-
-    #[test]
-    fn initialization() -> Result<()> {
-        let server = TestServerBuilder::new()?
-            .build()?
-            .wait_until_workspaces_are_initialized()?;
-
-        let initialization_result = server.initialization_result().unwrap();
-
-        insta::assert_json_snapshot!("initialization", initialization_result);
-
-        Ok(())
-    }
-
-    #[test]
-    fn initialization_with_workspace() -> Result<()> {
-        let workspace_root = SystemPath::new("foo");
-        let server = TestServerBuilder::new()?
-            .with_workspace(workspace_root, ClientOptions::default())?
-            .build()?
-            .wait_until_workspaces_are_initialized()?;
-
-        let initialization_result = server.initialization_result().unwrap();
-
-        insta::assert_json_snapshot!("initialization_with_workspace", initialization_result);
-
-        Ok(())
-    }
-
-    #[test]
-    fn publish_diagnostics_on_did_open() -> Result<()> {
-        let workspace_root = SystemPath::new("src");
-        let foo = SystemPath::new("src/foo.py");
-        let foo_content = "\
-def foo() -> str:
-    return 42
-";
-
-        let mut server = TestServerBuilder::new()?
-            .with_workspace(workspace_root, ClientOptions::default())?
-            .with_file(foo, foo_content)?
-            .enable_pull_diagnostics(false)
-            .build()?
-            .wait_until_workspaces_are_initialized()?;
-
-        server.open_text_document(foo, &foo_content, 1);
-        let diagnostics = server.await_notification::<PublishDiagnostics>()?;
-
-        insta::assert_debug_snapshot!(diagnostics);
-
-        Ok(())
-    }
-
-    #[test]
-    fn pull_diagnostics_on_did_open() -> Result<()> {
-        let workspace_root = SystemPath::new("src");
-        let foo = SystemPath::new("src/foo.py");
-        let foo_content = "\
-def foo() -> str:
-    return 42
-";
-
-        let mut server = TestServerBuilder::new()?
-            .with_workspace(workspace_root, ClientOptions::default())?
-            .with_file(foo, foo_content)?
-            .enable_pull_diagnostics(true)
-            .build()?
-            .wait_until_workspaces_are_initialized()?;
-
-        server.open_text_document(foo, &foo_content, 1);
-        let diagnostics = server.document_diagnostic_request(foo)?;
-
-        insta::assert_debug_snapshot!(diagnostics);
-
-        Ok(())
-    }
-}

crates/ty_server/src/session.rs

@@ -21,7 +21,8 @@ use ty_project::{ChangeResult, Db as _, ProjectDatabase, ProjectMetadata};
 
 pub(crate) use self::capabilities::ResolvedClientCapabilities;
 pub(crate) use self::index::DocumentQuery;
-pub(crate) use self::options::{AllOptions, ClientOptions, DiagnosticMode};
+pub use self::options::ClientOptions;
+pub(crate) use self::options::{AllOptions, DiagnosticMode};
 pub(crate) use self::settings::ClientSettings;
 use crate::document::{DocumentKey, DocumentVersion, NotebookDocument};
 use crate::server::publish_settings_diagnostics;

crates/ty_server/src/session/options.rs

@@ -49,9 +49,10 @@ struct WorkspaceOptions {
 
 /// This is a direct representation of the settings schema sent by the client.
 #[derive(Clone, Debug, Deserialize, Default)]
-#[cfg_attr(test, derive(serde::Serialize, PartialEq, Eq))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
+#[cfg_attr(feature = "testing", derive(serde::Serialize))]
 #[serde(rename_all = "camelCase")]
-pub(crate) struct ClientOptions {
+pub struct ClientOptions {
     /// Settings under the `python.*` namespace in VS Code that are useful for the ty language
     /// server.
     python: Option<Python>,
@@ -63,7 +64,8 @@ pub(crate) struct ClientOptions {
 
 /// Diagnostic mode for the language server.
 #[derive(Clone, Copy, Debug, Default, Deserialize)]
-#[cfg_attr(test, derive(serde::Serialize, PartialEq, Eq))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
+#[cfg_attr(feature = "testing", derive(serde::Serialize))]
 #[serde(rename_all = "camelCase")]
 pub(crate) enum DiagnosticMode {
     /// Check only currently open files.
@@ -147,21 +149,24 @@ impl ClientOptions {
 // all settings and not just the ones in "python.*".
 
 #[derive(Clone, Debug, Deserialize, Default)]
-#[cfg_attr(test, derive(serde::Serialize, PartialEq, Eq))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
+#[cfg_attr(feature = "testing", derive(serde::Serialize))]
 #[serde(rename_all = "camelCase")]
 struct Python {
     ty: Option<Ty>,
 }
 
 #[derive(Clone, Debug, Deserialize, Default)]
-#[cfg_attr(test, derive(serde::Serialize, PartialEq, Eq))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
+#[cfg_attr(feature = "testing", derive(serde::Serialize))]
 #[serde(rename_all = "camelCase")]
 struct PythonExtension {
     active_environment: Option<ActiveEnvironment>,
 }
 
 #[derive(Clone, Debug, Deserialize)]
-#[cfg_attr(test, derive(serde::Serialize, PartialEq, Eq))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
+#[cfg_attr(feature = "testing", derive(serde::Serialize))]
 #[serde(rename_all = "camelCase")]
 pub(crate) struct ActiveEnvironment {
     pub(crate) executable: PythonExecutable,
@@ -170,7 +175,8 @@ pub(crate) struct ActiveEnvironment {
 }
 
 #[derive(Clone, Debug, Deserialize)]
-#[cfg_attr(test, derive(serde::Serialize, PartialEq, Eq))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
+#[cfg_attr(feature = "testing", derive(serde::Serialize))]
 #[serde(rename_all = "camelCase")]
 pub(crate) struct EnvironmentVersion {
     pub(crate) major: i64,
@@ -182,7 +188,8 @@ pub(crate) struct EnvironmentVersion {
 }
 
 #[derive(Clone, Debug, Deserialize)]
-#[cfg_attr(test, derive(serde::Serialize, PartialEq, Eq))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
+#[cfg_attr(feature = "testing", derive(serde::Serialize))]
 #[serde(rename_all = "camelCase")]
 pub(crate) struct PythonEnvironment {
     pub(crate) folder_uri: Url,
@@ -194,7 +201,8 @@ pub(crate) struct PythonEnvironment {
 }
 
 #[derive(Clone, Debug, Deserialize)]
-#[cfg_attr(test, derive(serde::Serialize, PartialEq, Eq))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
+#[cfg_attr(feature = "testing", derive(serde::Serialize))]
 #[serde(rename_all = "camelCase")]
 pub(crate) struct PythonExecutable {
     #[allow(dead_code)]
@@ -203,7 +211,8 @@ pub(crate) struct PythonExecutable {
 }
 
 #[derive(Clone, Debug, Deserialize, Default)]
-#[cfg_attr(test, derive(serde::Serialize, PartialEq, Eq))]
+#[cfg_attr(test, derive(PartialEq, Eq))]
+#[cfg_attr(feature = "testing", derive(serde::Serialize))]
 #[serde(rename_all = "camelCase")]
 struct Ty {
     disable_language_services: Option<bool>,

crates/ty_server/tests/e2e/initialize.rs

@@ -0,0 +1,33 @@
+use anyhow::Result;
+use ruff_db::system::SystemPath;
+use ty_server::ClientOptions;
+
+use crate::TestServerBuilder;
+
+#[test]
+fn empty_workspace_folders() -> Result<()> {
+    let server = TestServerBuilder::new()?
+        .build()?
+        .wait_until_workspaces_are_initialized()?;
+
+    let initialization_result = server.initialization_result().unwrap();
+
+    insta::assert_json_snapshot!("initialization", initialization_result);
+
+    Ok(())
+}
+
+#[test]
+fn single_workspace_folder() -> Result<()> {
+    let workspace_root = SystemPath::new("foo");
+    let server = TestServerBuilder::new()?
+        .with_workspace(workspace_root, ClientOptions::default())?
+        .build()?
+        .wait_until_workspaces_are_initialized()?;
+
+    let initialization_result = server.initialization_result().unwrap();
+
+    insta::assert_json_snapshot!("initialization_with_workspace", initialization_result);
+
+    Ok(())
+}

crates/ty_server/tests/e2e/main.rs

@@ -1,9 +1,35 @@
 //! Testing server for the ty language server.
 //!
-//! This module provides mock server infrastructure for testing LSP functionality using
-//! temporary directories on the real filesystem.
+//! This module provides mock server infrastructure for testing LSP functionality using a
+//! temporary directory on the real filesystem.
 //!
 //! The design is inspired by the Starlark LSP test server but adapted for ty server architecture.
+//!
+//! To get started, use the [`TestServerBuilder`] to configure the server with workspace folders,
+//! enable or disable specific client capabilities, and add test files. Then, use the [`build`]
+//! method to create the [`TestServer`]. This will start the server and perform the initialization
+//! handshake. It might be useful to call [`wait_until_workspaces_are_initialized`] to ensure that
+//! the server side initialization is complete before sending any requests.
+//!
+//! Once the setup is done, you can use the server to [`send_request`] and [`send_notification`] to
+//! send messages to the server and [`await_response`], [`await_request`], and
+//! [`await_notification`] to wait for responses, requests, and notifications from the server.
+//!
+//! The [`Drop`] implementation of the [`TestServer`] ensures that the server is shut down
+//! gracefully using the LSP protocol. It also asserts that all messages sent by the server
+//! have been handled by the test client before the server is dropped.
+//!
+//! [`build`]: TestServerBuilder::build
+//! [`wait_until_workspaces_are_initialized`]: TestServer::wait_until_workspaces_are_initialized
+//! [`send_request`]: TestServer::send_request
+//! [`send_notification`]: TestServer::send_notification
+//! [`await_response`]: TestServer::await_response
+//! [`await_request`]: TestServer::await_request
+//! [`await_notification`]: TestServer::await_notification
+
+mod initialize;
+mod publish_diagnostics;
+mod pull_diagnostics;
 
 use std::collections::hash_map::Entry;
 use std::collections::{HashMap, VecDeque};
@@ -39,9 +65,7 @@ use rustc_hash::FxHashMap;
 use serde::de::DeserializeOwned;
 use tempfile::TempDir;
 
-use crate::logging::{LogLevel, init_logging};
-use crate::server::Server;
-use crate::session::ClientOptions;
+use ty_server::{ClientOptions, LogLevel, Server, init_logging};
 
 /// Number of times to retry receiving a message before giving up
 const RETRY_COUNT: usize = 5;
@@ -86,10 +110,6 @@ impl TestServerError {
 
 /// A test server for the ty language server that provides helpers for sending requests,
 /// correlating responses, and handling notifications.
-///
-/// The [`Drop`] implementation ensures that the server is shut down gracefully using the described
-/// protocol in the LSP specification. It also ensures that all messages sent by the server have
-/// been handled by the test client before the server is dropped.
 pub(crate) struct TestServer {
     /// The thread that's actually running the server.
     ///
@@ -103,10 +123,10 @@ pub(crate) struct TestServer {
     /// the connection to be cleaned up properly.
     client_connection: Option<Connection>,
 
-    /// Test directory that holds all test files.
+    /// Test context that provides the project root directory that holds all test files.
     ///
     /// This directory is automatically cleaned up when the [`TestServer`] is dropped.
-    test_dir: TestContext,
+    test_context: TestContext,
 
     /// Incrementing counter to automatically generate request IDs
     request_counter: i32,
@@ -175,7 +195,7 @@ impl TestServer {
         Self {
             server_thread: Some(server_thread),
             client_connection: Some(client_connection),
-            test_dir,
+            test_context: test_dir,
             request_counter: 0,
             responses: FxHashMap::default(),
             notifications: VecDeque::new(),
@@ -297,9 +317,9 @@ impl TestServer {
 
     /// Send a request to the server and return the request ID.
     ///
-    /// The caller can use this ID to later retrieve the response using [`get_response`].
+    /// The caller can use this ID to later retrieve the response using [`await_response`].
     ///
-    /// [`get_response`]: TestServer::get_response
+    /// [`await_response`]: TestServer::await_response
     pub(crate) fn send_request<R>(&mut self, params: R::Params) -> RequestId
     where
         R: Request,
@@ -505,7 +525,7 @@ impl TestServer {
     /// Use the [`get_request`] method to wait for the server to send this request.
     ///
     /// [`get_request`]: TestServer::get_request
-    pub(crate) fn handle_workspace_configuration_request(
+    fn handle_workspace_configuration_request(
         &mut self,
         request_id: RequestId,
         params: &ConfigurationParams,
@@ -548,7 +568,7 @@ impl TestServer {
     }
 
     fn file_uri(&self, path: impl AsRef<SystemPath>) -> Url {
-        Url::from_file_path(self.test_dir.root().join(path.as_ref()).as_std_path())
+        Url::from_file_path(self.test_context.root().join(path.as_ref()).as_std_path())
             .expect("Path must be a valid URL")
     }
 
@@ -628,7 +648,7 @@ impl TestServer {
 impl fmt::Debug for TestServer {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("TestServer")
-            .field("temp_dir", &self.test_dir.root())
+            .field("temp_dir", &self.test_context.root())
             .field("request_counter", &self.request_counter)
             .field("responses", &self.responses)
             .field("notifications", &self.notifications)
@@ -750,6 +770,7 @@ impl TestServerBuilder {
     }
 
     /// Enable or disable pull diagnostics capability
+    #[must_use]
     pub(crate) fn enable_pull_diagnostics(mut self, enabled: bool) -> Self {
         self.client_capabilities
             .text_document
@@ -763,6 +784,7 @@ impl TestServerBuilder {
     }
 
     /// Enable or disable file watching capability
+    #[must_use]
     #[expect(dead_code)]
     pub(crate) fn enable_did_change_watched_files(mut self, enabled: bool) -> Self {
         self.client_capabilities
@@ -777,6 +799,7 @@ impl TestServerBuilder {
     }
 
     /// Set custom client capabilities (overrides any previously set capabilities)
+    #[must_use]
     #[expect(dead_code)]
     pub(crate) fn with_client_capabilities(mut self, capabilities: ClientCapabilities) -> Self {
         self.client_capabilities = capabilities;
@@ -798,7 +821,7 @@ impl TestServerBuilder {
         Ok(self)
     }
 
-    /// Write multiple files to the temporary directory
+    /// Write multiple files to the test directory
     #[expect(dead_code)]
     pub(crate) fn with_files<P, C, I>(mut self, files: I) -> Result<Self>
     where

crates/ty_server/tests/e2e/publish_diagnostics.rs

@@ -0,0 +1,30 @@
+use anyhow::Result;
+use lsp_types::notification::PublishDiagnostics;
+use ruff_db::system::SystemPath;
+use ty_server::ClientOptions;
+
+use crate::TestServerBuilder;
+
+#[test]
+fn on_did_open() -> Result<()> {
+    let workspace_root = SystemPath::new("src");
+    let foo = SystemPath::new("src/foo.py");
+    let foo_content = "\
+def foo() -> str:
+    return 42
+";
+
+    let mut server = TestServerBuilder::new()?
+        .with_workspace(workspace_root, ClientOptions::default())?
+        .with_file(foo, foo_content)?
+        .enable_pull_diagnostics(false)
+        .build()?
+        .wait_until_workspaces_are_initialized()?;
+
+    server.open_text_document(foo, &foo_content, 1);
+    let diagnostics = server.await_notification::<PublishDiagnostics>()?;
+
+    insta::assert_debug_snapshot!(diagnostics);
+
+    Ok(())
+}

crates/ty_server/tests/e2e/pull_diagnostics.rs

@@ -0,0 +1,29 @@
+use anyhow::Result;
+use ruff_db::system::SystemPath;
+use ty_server::ClientOptions;
+
+use crate::TestServerBuilder;
+
+#[test]
+fn on_did_open() -> Result<()> {
+    let workspace_root = SystemPath::new("src");
+    let foo = SystemPath::new("src/foo.py");
+    let foo_content = "\
+def foo() -> str:
+    return 42
+";
+
+    let mut server = TestServerBuilder::new()?
+        .with_workspace(workspace_root, ClientOptions::default())?
+        .with_file(foo, foo_content)?
+        .enable_pull_diagnostics(true)
+        .build()?
+        .wait_until_workspaces_are_initialized()?;
+
+    server.open_text_document(foo, &foo_content, 1);
+    let diagnostics = server.document_diagnostic_request(foo)?;
+
+    insta::assert_debug_snapshot!(diagnostics);
+
+    Ok(())
+}

crates/ty_server/tests/e2e/snapshots/e2e__initialize__initialization.snap

@@ -1,5 +1,5 @@
 ---
-source: crates/ty_server/src/server.rs
+source: crates/ty_server/tests/e2e/initialize.rs
 expression: initialization_result
 ---
 {

crates/ty_server/tests/e2e/snapshots/e2e__initialize__initialization_with_workspace.snap

@@ -1,5 +1,5 @@
 ---
-source: crates/ty_server/src/server.rs
+source: crates/ty_server/tests/e2e/initialize.rs
 expression: initialization_result
 ---
 {

crates/ty_server/tests/e2e/snapshots/e2e__publish_diagnostics__on_did_open.snap

@@ -1,5 +1,5 @@
 ---
-source: crates/ty_server/src/server.rs
+source: crates/ty_server/tests/e2e/publish_diagnostics.rs
 expression: diagnostics
 ---
 PublishDiagnosticsParams {

crates/ty_server/tests/e2e/snapshots/e2e__pull_diagnostics__on_did_open.snap

@@ -1,5 +1,5 @@
 ---
-source: crates/ty_server/src/server.rs
+source: crates/ty_server/tests/e2e/pull_diagnostics.rs
 expression: diagnostics
 ---
 Report(