diff --git a/packages/language-service/src/features/__fixtures__/diagnostics.html b/packages/language-service/src/features/__fixtures__/diagnostics.html
new file mode 100644
index 0000000..0c5d87e
--- /dev/null
+++ b/packages/language-service/src/features/__fixtures__/diagnostics.html
@@ -0,0 +1,6 @@
+<!-- ok with: default from "./diagnostics" -->
+<p data-bind="text: helo"></p>
+<!-- ko if: true -->
+hello
+<!-- /ko -->
+<!-- /ok -->
diff --git a/packages/language-service/src/features/__fixtures__/hover.viewmodel.ts b/packages/language-service/src/features/__fixtures__/diagnostics.ts
similarity index 100%
rename from packages/language-service/src/features/__fixtures__/hover.viewmodel.ts
rename to packages/language-service/src/features/__fixtures__/diagnostics.ts
diff --git a/packages/language-service/src/features/__fixtures__/hover.html b/packages/language-service/src/features/__fixtures__/hover.html
index 5c9fd2b..8f33c22 100644
--- a/packages/language-service/src/features/__fixtures__/hover.html
+++ b/packages/language-service/src/features/__fixtures__/hover.html
@@ -1,3 +1,3 @@
-<!-- ok with: default from "./hover.viewmodel" -->
+<!-- ok with: default from "./hover" -->
 <p data-bind="text: hello"></p>
 <!-- /ok -->
diff --git a/packages/language-service/src/features/__fixtures__/hover.ts b/packages/language-service/src/features/__fixtures__/hover.ts
new file mode 100644
index 0000000..f15b597
--- /dev/null
+++ b/packages/language-service/src/features/__fixtures__/hover.ts
@@ -0,0 +1,3 @@
+export default class {
+  hello = "hello";
+}
diff --git a/packages/language-service/src/features/__fixtures__/tsconfig.json b/packages/language-service/src/features/__fixtures__/tsconfig.json
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/packages/language-service/src/features/__fixtures__/tsconfig.json
@@ -0,0 +1 @@
+{}
diff --git a/packages/language-service/src/features/diagnostics.spec.ts b/packages/language-service/src/features/diagnostics.spec.ts
new file mode 100644
index 0000000..7a432db
--- /dev/null
+++ b/packages/language-service/src/features/diagnostics.spec.ts
@@ -0,0 +1,38 @@
+import { type Diagnostics, LanguageService } from "../index.js";
+import { describe, beforeAll, it, expect } from "@jest/globals";
+import { readFile } from "node:fs/promises";
+import { fileURLToPath } from "node:url";
+
+describe("diagnostics", () => {
+  let diagnostics!: Diagnostics;
+
+  beforeAll(async () => {
+    const service = new LanguageService({
+      worker: false,
+    });
+    const fileName = fileURLToPath(
+      new URL("__fixtures__/diagnostics.html", import.meta.url),
+    );
+    const text = await readFile(fileName, "utf8");
+    await service.openDocument(fileName, text);
+    diagnostics = await service.getDiagnostics({
+      fileName: fileName,
+    });
+  });
+
+  it("provides standard diagnostics", async () => {
+    const diagnostic = diagnostics.find(
+      (diagnostic) => diagnostic.code === "virtual-element-end-notation",
+    );
+    expect(diagnostic).not.toBe(undefined);
+    expect(diagnostic!.range.start.line).toBe(4);
+  });
+
+  it("provides typescript diagnostics", async () => {
+    const diagnostic = diagnostics.find(
+      (diagnostic) => diagnostic.code === "ts/2552",
+    );
+    expect(diagnostic).not.toBe(undefined);
+    expect(diagnostic!.range.start.line).toBe(1);
+  });
+});