diff --git a/backend/src/api.ts b/backend/src/api.ts
index a0ba51b..e63c8a5 100644
--- a/backend/src/api.ts
+++ b/backend/src/api.ts
@@ -4,6 +4,7 @@ import * as WebSocket from "ws";
 
 import * as pty from "node-pty";
 import { IPty } from "node-pty";
+import PQueue from "p-queue";
 import * as rpc from "vscode-jsonrpc";
 import { v4 as getUUID } from "uuid";
 
@@ -44,6 +45,8 @@ export class Session {
 
   logPrimitive: (msg: string) => void;
 
+  msgQueue: PQueue = new PQueue({ concurrency: 1 });
+
   get homedir() {
     return `/tmp/riju/${this.uuid}`;
   }
@@ -158,7 +161,9 @@ export class Session {
         );
         this.send({ event: "lspStarted", root: this.homedir });
       }
-      this.ws.on("message", this.receive);
+      this.ws.on("message", (msg: string) =>
+        this.msgQueue.add(() => this.receive(msg))
+      );
       this.ws.on("close", async () => {
         await this.teardown();
       });
diff --git a/backend/src/langs.ts b/backend/src/langs.ts
index 1d8b58c..2ad5df1 100644
--- a/backend/src/langs.ts
+++ b/backend/src/langs.ts
@@ -1388,8 +1388,14 @@ main = do
         },
       },
     },
-    template: `print('Hello, world!')
+    template: `print("Hello, world!")
 `,
+    test: {
+      format: {
+        input: `print('Hello, world!')
+`,
+      },
+    },
   },
   قلب: {
     aliases: ["qalb"],
diff --git a/backend/src/test-runner.ts b/backend/src/test-runner.ts
index 9c23c99..7d5ba9c 100644
--- a/backend/src/test-runner.ts
+++ b/backend/src/test-runner.ts
@@ -86,6 +86,9 @@ class Test {
         case "repl":
           await this.testRepl();
           break;
+        case "runrepl":
+          await this.testRunRepl();
+          break;
         case "scope":
           await this.testScope();
           break;
@@ -265,18 +268,48 @@ async function main() {
       [lang, test].concat(langs[lang].aliases || []).includes(arg)
     );
   }
+  if (tests.length === 0) {
+    console.error("no tests selected");
+    process.exit(1);
+  }
+  const lintSeen = new Set();
+  let lintPassed = 0;
+  let lintFailed = 0;
+  for (const { lang } of tests) {
+    if (!lintSeen.has(lang)) {
+      lintSeen.add(lang);
+      console.error(`===== LANGUAGE ${lang}, LINT`);
+      try {
+        lint(lang);
+        console.error("passed");
+        lintPassed += 1;
+      } catch (err) {
+        console.error("failed");
+        console.error(err);
+        lintFailed += 1;
+      }
+    }
+  }
+  if (lintFailed) {
+    process.exit(1);
+  }
+  let passed = 0;
+  let failed = 0;
   for (const { lang, test: type } of tests) {
     console.error(`===== LANGUAGE ${lang}, TEST ${type}`);
     const test = new Test(lang, type);
     try {
       await test.run();
-      console.error("succeeded");
+      console.error("passed");
+      passed += 1;
     } catch (err) {
-      console.error("failed:");
+      console.error("failed");
       console.error(test.getLog());
       console.error(err);
+      failed += 1;
     }
   }
+  process.exit(failed ? 1 : 0);
 }
 
 main().catch(console.error);
diff --git a/package.json b/package.json
index d8f00c3..3dd9f95 100644
--- a/package.json
+++ b/package.json
@@ -33,6 +33,7 @@
     "monaco-languageclient": "^0.13.0",
     "node-pty": "^0.9.0",
     "npm-run-all": "^4.1.5",
+    "p-queue": "^6.6.0",
     "parse-passwd": "^1.0.0",
     "shell-quote": "^1.7.2",
     "style-loader": "^1.2.1",
diff --git a/yarn.lock b/yarn.lock
index de64bc2..30f466d 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2118,6 +2118,11 @@ etag@~1.8.1:
   resolved "https://registry.yarnpkg.com/etag/-/etag-1.8.1.tgz#41ae2eeb65efa62268aebfea83ac7d79299b0887"
   integrity sha1-Qa4u62XvpiJorr/qg6x9eSmbCIc=
 
+eventemitter3@^4.0.4:
+  version "4.0.4"
+  resolved "https://registry.yarnpkg.com/eventemitter3/-/eventemitter3-4.0.4.tgz#b5463ace635a083d018bdc7c917b4c5f10a85384"
+  integrity sha512-rlaVLnVxtxvoyLsQQFBx53YmXHDxRIzzTLbdfxqi4yocpSjAxXwkU0cScM5JgSKMqEhrZpnvQ2D9gjylR0AimQ==
+
 events@^3.0.0:
   version "3.1.0"
   resolved "https://registry.yarnpkg.com/events/-/events-3.1.0.tgz#84279af1b34cb75aa88bf5ff291f6d0bd9b31a59"
@@ -3659,6 +3664,21 @@ p-locate@^3.0.0:
   dependencies:
     p-limit "^2.0.0"
 
+p-queue@^6.6.0:
+  version "6.6.0"
+  resolved "https://registry.yarnpkg.com/p-queue/-/p-queue-6.6.0.tgz#263f2b73add4cefca81d8d6b2696ee74b326de2f"
+  integrity sha512-zPHXPNy9jZsiym0PpJjvnHQysx1fSd/QdaNVwiDRLU2KFChD6h9CkCB6b8i3U8lBwJyA+mHgNZCzcy77glUssQ==
+  dependencies:
+    eventemitter3 "^4.0.4"
+    p-timeout "^3.1.0"
+
+p-timeout@^3.1.0:
+  version "3.2.0"
+  resolved "https://registry.yarnpkg.com/p-timeout/-/p-timeout-3.2.0.tgz#c7e17abc971d2a7962ef83626b35d635acf23dfe"
+  integrity sha512-rhIwUycgwwKcP9yTOOFK/AKsAopjjCakVqLHePO3CC6Mir1Z99xT+R63jZxAT5lFZLa2inS5h+ZS2GvR99/FBg==
+  dependencies:
+    p-finally "^1.0.0"
+
 p-try@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/p-try/-/p-try-1.0.0.tgz#cbc79cdbaf8fd4228e13f621f2b1a237c1b207b3"