diff --git a/.vscode/extensions.json b/.vscode/extensions.json
new file mode 100644
index 0000000..c83e263
--- /dev/null
+++ b/.vscode/extensions.json
@@ -0,0 +1,3 @@
+{
+  "recommendations": ["esbenp.prettier-vscode"]
+}
diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..8ce4949
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,5 @@
+{
+  "[typescript]": {
+    "editor.defaultFormatter": "esbenp.prettier-vscode"
+  }
+}
diff --git a/src/client.ts b/src/client.ts
index c2428fc..53042bb 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -1,8 +1,23 @@
-import { workspace, WorkspaceFolder, Uri, window, OutputChannel } from "vscode";
+import {
+  workspace,
+  WorkspaceFolder,
+  Uri,
+  window,
+  tests,
+  TestRunProfileKind,
+  Range,
+  TestItem,
+  TestMessage,
+  TestController,
+  OutputChannel,
+  CancellationToken,
+  TestRunRequest,
+} from "vscode";
 
 import {
   LanguageClient,
   LanguageClientOptions,
+  ServerCapabilities,
   ServerOptions,
   TextDocumentFilter,
 } from "vscode-languageclient/node";
@@ -10,6 +25,33 @@ import {
 import { extensionName, languageId } from "./constants";
 import findNargo from "./find-nargo";
 
+type NargoCapabilities = {
+  nargo?: {
+    tests?: {
+      fetch: boolean;
+      run: boolean;
+      update: boolean;
+    };
+  };
+};
+
+type NargoTests = {
+  package: string;
+  uri: string;
+  tests?: {
+    id: string;
+    label: string;
+    uri: string;
+    range: Range;
+  }[];
+};
+
+type RunTestResult = {
+  id: string;
+  result: "pass" | "fail" | "error";
+  message: string;
+};
+
 function globFromUri(uri: Uri, glob: string) {
   // globs always need to use `/`
   return `${uri.fsPath}${glob}`.replaceAll("\\", "/");
@@ -40,6 +82,11 @@ export default class Client extends LanguageClient {
   #args: string[];
   #output: OutputChannel;
 
+  // This function wasn't added until vscode 1.81.0 so fake the type
+  #testController: TestController & {
+    invalidateTestResults?: (item: TestItem) => void;
+  };
+
   constructor(uri: Uri, workspaceFolder?: WorkspaceFolder) {
     let outputChannel = window.createOutputChannel(extensionName, languageId);
 
@@ -78,6 +125,153 @@ export default class Client extends LanguageClient {
     this.#command = command;
     this.#args = args;
     this.#output = outputChannel;
+
+    // TODO: Figure out how to do type-safe onNotification
+    this.onNotification("nargo/tests/update", (testData: NargoTests) => {
+      this.#updateTests(testData);
+    });
+
+    this.registerFeature({
+      fillClientCapabilities: () => {},
+      initialize: (capabilities: ServerCapabilities & NargoCapabilities) => {
+        outputChannel.appendLine(`${JSON.stringify(capabilities)}`);
+        if (typeof capabilities.nargo?.tests !== "undefined") {
+          this.#testController = tests.createTestController(
+            // We prefix with our ID namespace but we also tie these to the URI since they need to be unique
+            `NoirWorkspaceTests-${uri.toString()}`,
+            "Noir Workspace Tests"
+          );
+
+          if (capabilities.nargo.tests.fetch) {
+            // TODO: reload a single test if provided as the function argument
+            this.#testController.resolveHandler = async (test) => {
+              await this.#fetchTests();
+            };
+            this.#testController.refreshHandler = async (token) => {
+              await this.#refreshTests(token);
+            };
+          }
+
+          if (capabilities.nargo.tests.run) {
+            this.#testController.createRunProfile(
+              "Run Tests",
+              TestRunProfileKind.Run,
+              async (request, token) => {
+                await this.#runTest(request, token);
+              },
+              true
+            );
+          }
+        }
+      },
+      getState: () => {
+        return { kind: "static" };
+      },
+      dispose: () => {
+        if (this.#testController) {
+          this.#testController.dispose();
+        }
+      },
+    });
+  }
+
+  async #fetchTests() {
+    const response = await this.sendRequest<NargoTests[]>("nargo/tests", {});
+
+    response.forEach((testData) => {
+      this.#createTests(testData);
+    });
+  }
+
+  async #refreshTests(token: CancellationToken) {
+    const response = await this.sendRequest<NargoTests[]>(
+      "nargo/tests",
+      {},
+      token
+    );
+    response.forEach((testData) => {
+      this.#updateTests(testData);
+    });
+  }
+
+  async #runTest(request: TestRunRequest, token: CancellationToken) {
+    const run = this.#testController.createTestRun(request);
+    const queue: TestItem[] = [];
+
+    // Loop through all included tests, or all known tests, and add them to our queue
+    if (request.include) {
+      request.include.forEach((test) => queue.push(test));
+    } else {
+      this.#testController.items.forEach((test) => queue.push(test));
+    }
+
+    while (queue.length > 0 && !token.isCancellationRequested) {
+      const test = queue.pop()!;
+
+      // Skip tests the user asked to exclude
+      if (request.exclude?.includes(test)) {
+        continue;
+      }
+
+      // We don't run our test headers since they are just for grouping
+      // but this is fine because the test pass/fail icons are propagated upward
+      if (test.parent) {
+        // If we have these tests, the server will be able to run them with this message
+        const { id, result, message } = await this.sendRequest<RunTestResult>(
+          "nargo/tests/run",
+          {
+            id: test.id,
+          },
+          token
+        );
+
+        // TODO: Handle `test.id !== id`. I'm not sure if it is possible for this to happen in normal usage
+
+        if (result === "pass") {
+          run.passed(test);
+          continue;
+        }
+
+        if (result === "fail" || result === "error") {
+          run.failed(test, new TestMessage(message));
+          continue;
+        }
+      }
+
+      // After tests are run (if any), we add any children to the queue
+      test.children.forEach((test) => queue.push(test));
+    }
+
+    run.end();
+  }
+
+  #createTests(testData: NargoTests) {
+    let pkg = this.#testController.createTestItem(
+      testData.package,
+      testData.package
+    );
+
+    testData.tests.forEach((test) => {
+      let item = this.#testController.createTestItem(
+        test.id,
+        test.label,
+        Uri.parse(test.uri)
+      );
+      item.range = test.range;
+      pkg.children.add(item);
+    });
+
+    this.#testController.items.add(pkg);
+  }
+
+  #updateTests(testData: NargoTests) {
+    // This function wasn't added until vscode 1.81.0 so we check for it
+    if (typeof this.#testController.invalidateTestResults === "function") {
+      let pkg = this.#testController.items.get(testData.package);
+      this.#testController.invalidateTestResults(pkg);
+    }
+
+    this.#createTests(testData);
   }
 
   async start(): Promise<void> {