diff --git a/src/test/lsp.tests.js b/src/test/lsp.tests.js
new file mode 100644
index 000000000..0b63b78cf
--- /dev/null
+++ b/src/test/lsp.tests.js
@@ -0,0 +1,230 @@
+import {
+	checkRuntimeServerInstallation,
+	createTransport,
+	selectRuntimeProvider,
+} from "cm/lsp";
+import lspApi from "cm/lsp/api";
+import { TestRunner } from "./tester";
+
+const ROOT_URI = "file:///tmp";
+const DEFAULT_TIMEOUT = 10000;
+const CLEANUP_GRACE_PERIOD = 5000;
+
+function timeoutFor(server) {
+	const timeout = Number(server.startupTimeout);
+	return Number.isFinite(timeout) && timeout > 0 ? timeout : DEFAULT_TIMEOUT;
+}
+
+function withTimeout(promise, timeout, message) {
+	return new Promise((resolve, reject) => {
+		const timer = setTimeout(() => reject(new Error(message)), timeout);
+		Promise.resolve(promise).then(
+			(value) => {
+				clearTimeout(timer);
+				resolve(value);
+			},
+			(error) => {
+				clearTimeout(timer);
+				reject(error);
+			},
+		);
+	});
+}
+
+function initializationRequest(id = 1) {
+	return {
+		jsonrpc: "2.0",
+		id,
+		method: "initialize",
+		params: {
+			processId: null,
+			clientInfo: {
+				name: "Acode",
+				version: "1.0",
+			},
+			rootUri: ROOT_URI,
+			capabilities: {},
+			workspaceFolders: null,
+		},
+	};
+}
+
+function isObject(value) {
+	return value !== null && typeof value === "object" && !Array.isArray(value);
+}
+
+export function isValidInitializationResponse(response, id = 1) {
+	return (
+		isObject(response) &&
+		response.jsonrpc === "2.0" &&
+		response.id === id &&
+		isObject(response.result) &&
+		isObject(response.result.capabilities)
+	);
+}
+
+function waitForInitialization(transport, server, timeout) {
+	const id = 1;
+	return new Promise((resolve, reject) => {
+		let settled = false;
+		const finish = (error, response) => {
+			if (settled) return;
+			settled = true;
+			clearTimeout(timer);
+			transport.unsubscribe?.(onMessage);
+			if (error) reject(error);
+			else resolve(response);
+		};
+		const onMessage = (data) => {
+			let payload;
+			try {
+				payload = typeof data === "string" ? JSON.parse(data) : data;
+			} catch {
+				return;
+			}
+			const messages = Array.isArray(payload) ? payload : [payload];
+			const response = messages.find((message) => message?.id === id);
+			if (!response) return;
+			if (response.error) {
+				const detail = response.error.message || JSON.stringify(response.error);
+				finish(new Error(`${server.label} rejected initialize: ${detail}`));
+				return;
+			}
+			if (!isValidInitializationResponse(response, id)) {
+				finish(
+					new Error(`${server.label} returned an invalid initialize result`),
+				);
+				return;
+			}
+			finish(null, response);
+		};
+		const timer = setTimeout(() => {
+			finish(
+				new Error(
+					`${server.label} did not respond to initialize within ${timeout}ms`,
+				),
+			);
+		}, timeout);
+
+		transport.subscribe(onMessage);
+		try {
+			transport.send(JSON.stringify(initializationRequest(id)));
+		} catch (error) {
+			finish(error);
+		}
+	});
+}
+
+function createRuntimeContext(server) {
+	return {
+		uri: ROOT_URI,
+		documentUri: ROOT_URI,
+		originalDocumentUri: ROOT_URI,
+		rootUri: ROOT_URI,
+		originalRootUri: ROOT_URI,
+		serverId: server.id,
+		workspaceKind: "app-private",
+		allowNonTerminalWorkspace: true,
+	};
+}
+
+function transportFromConnection(server, context, connection) {
+	if (connection.kind === "transport") {
+		return connection.transport;
+	}
+
+	return createTransport(
+		{
+			...server,
+			transport: {
+				...server.transport,
+				kind: "websocket",
+				url: connection.url,
+				protocols: connection.protocols,
+			},
+		},
+		context,
+	);
+}
+
+async function cleanup(provider, connection, transportHandle) {
+	const errors = [];
+	try {
+		await transportHandle?.dispose?.();
+	} catch (error) {
+		errors.push(error);
+	}
+	try {
+		await connection?.dispose?.();
+	} catch (error) {
+		errors.push(error);
+	}
+	try {
+		if (connection) await provider?.stop?.(connection);
+	} catch (error) {
+		errors.push(error);
+	}
+	if (errors.length) {
+		console.warn("Failed to completely clean up LSP test connection", errors);
+	}
+}
+
+async function testServer(server, test) {
+	const timeout = timeoutFor(server);
+	const context = createRuntimeContext(server);
+	const installation = await withTimeout(
+		checkRuntimeServerInstallation(server, context),
+		timeout,
+		`Timed out checking whether ${server.label} is installed`,
+	);
+
+	if (installation.status === "missing") {
+		return test.skip(`${server.label} is not installed`);
+	}
+
+	const provider = await withTimeout(
+		selectRuntimeProvider(server, context),
+		timeout,
+		`Timed out selecting a runtime for ${server.label}`,
+	);
+	if (!provider) {
+		throw new Error(`No runtime can start ${server.label}`);
+	}
+
+	let connection;
+	let transportHandle;
+	try {
+		connection = await withTimeout(
+			provider.start(server, context),
+			timeout,
+			`${server.label} did not start within ${timeout}ms`,
+		);
+		transportHandle = transportFromConnection(server, context, connection);
+		await withTimeout(
+			transportHandle.ready,
+			timeout,
+			`${server.label} transport was not ready within ${timeout}ms`,
+		);
+		await waitForInitialization(transportHandle.transport, server, timeout);
+	} finally {
+		await cleanup(provider, connection, transportHandle);
+	}
+}
+
+export async function runLspTests(writeOutput) {
+	const runner = new TestRunner("LSP Server Tests");
+	const servers = lspApi.servers.list();
+
+	for (const server of servers) {
+		const timeout = timeoutFor(server);
+		runner.test(
+			`${server.label} (${server.id}) initializes`,
+			(test) => testServer(server, test),
+			{
+				timeout: timeout * 5 + CLEANUP_GRACE_PERIOD,
+			},
+		);
+	}
+
+	return await runner.run(writeOutput);
+}
diff --git a/src/test/test-definitions.js b/src/test/test-definitions.js
index f29c7cead..9570cf026 100644
--- a/src/test/test-definitions.js
+++ b/src/test/test-definitions.js
@@ -2,6 +2,7 @@ import { runAceCompatibilityTests } from "./ace.test";
 import { runCodeMirrorTests } from "./editor.tests";
 import { runExecutorTests } from "./exec.tests";
 import { runFsTests } from "./fs.tests";
+import { runLspTests } from "./lsp.tests";
 import { runSanityTests } from "./sanity.tests";
 import { runUrlTests } from "./url.tests";
 
@@ -14,6 +15,7 @@ export const testDefinitions = [
 	runExecutorTests,
 	runUrlTests,
 	runFsTests,
+	runLspTests,
 	runCodeMirrorTests,
 	runAceCompatibilityTests,
 ];
diff --git a/src/test/tester.js b/src/test/tester.js
index 726dda10f..e686e0005 100644
--- a/src/test/tester.js
+++ b/src/test/tester.js
@@ -222,6 +222,7 @@ function createTestRunnerContent() {
 		e.preventDefault();
 		e.stopPropagation();
 		if (currentRunnerState.status !== "running") {
+			registerAllSuites();
 			runTestsInternal();
 		}
 	};
@@ -595,6 +596,7 @@ export function openTestRunnerTab() {
 	if (existingFile) {
 		existingFile.makeActive();
 		if (currentRunnerState.status !== "running") {
+			registerAllSuites();
 			runTestsInternal();
 		}
 		return;
@@ -670,8 +672,9 @@ class TestRunner {
 	/**
 	 * Register a test
 	 */
-	test(testName, testFn) {
-		this.tests.push({ name: testName, fn: testFn });
+	test(testName, testFn, options = {}) {
+		const timeout = typeof options === "number" ? options : options?.timeout;
+		this.tests.push({ name: testName, fn: testFn, timeout });
 		this.suiteState.tests.push({
 			name: testName,
 			status: "pending",
@@ -766,7 +769,7 @@ class TestRunner {
 			try {
 				await delay(50);
 
-				await this._runWithTimeout(test.fn, this, 10000);
+				await this._runWithTimeout(test.fn, this, test.timeout ?? 10000);
 
 				const duration = Math.max(
 					0,