diff --git a/lib/linter.js b/lib/linter.js
index f8c86b6..b5ff6c0 100644
--- a/lib/linter.js
+++ b/lib/linter.js
@@ -31,7 +31,7 @@ function translateOptions(cliOptions, cwd) {
 
 const eslintCache = new LRU(10);
 
-function linter(cwd, args, text) {
+exports.lint = function (cwd, args, text) {
   process.chdir(cwd);
   let cwdDeps = eslintCache.get(cwd);
   if (!cwdDeps) {
@@ -116,9 +116,9 @@ function linter(cwd, args, text) {
     output += '\n# exit 1';
   }
   return output;
-}
+};
 
-linter.getStatus = function () {
+exports.getStatus = function () {
   const { keys } = eslintCache;
   if (keys.length === 0) {
     return 'Running, no instances cached';
@@ -128,5 +128,3 @@ linter.getStatus = function () {
   }
   return `Running, ${keys.length} instances cached`;
 };
-
-module.exports = linter;
diff --git a/lib/server.js b/lib/server.js
index c8e2401..de49ea1 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -5,17 +5,19 @@ const net = require('net');
 const portfile = require('./portfile');
 const linter = require('./linter');
 
+function forceClose(con) {
+  try {
+    con.end('Server is stopping...\n# exit 1');
+  } catch (ignore) {
+    // Nothing we can do
+  }
+}
+
 exports.start = function () {
 
   const token = crypto.randomBytes(8).toString('hex');
-
   let openConnections = [];
 
-  function forceClose(con) {
-    con.write('Server is stopping...\n# exit 1');
-    con.end();
-  }
-
   const server = net.createServer({
     allowHalfOpen: true
   }, (con) => {
@@ -38,14 +40,13 @@ exports.start = function () {
       }
       data = data.substring(p + 1);
       if (data === 'stop') {
+        openConnections.forEach(forceClose);
         con.end();
         server.close();
-        openConnections.forEach(forceClose);
         return;
       }
       if (data === 'status') {
-        con.write(linter.getStatus());
-        con.end();
+        con.end(linter.getStatus());
         return;
       }
       let cwd, args, text;
@@ -65,7 +66,7 @@ exports.start = function () {
         args = parts.slice(1);
       }
       try {
-        con.write(linter(cwd, args, text));
+        con.write(linter.lint(cwd, args, text));
       } catch (e) {
         con.write(`${e.toString()}\n# exit 1`);
       }
diff --git a/test/server-test.js b/test/server-test.js
new file mode 100644
index 0000000..994c29f
--- /dev/null
+++ b/test/server-test.js
@@ -0,0 +1,211 @@
+/*eslint-env mocha*/
+'use strict';
+
+const net = require('net');
+const crypto = require('crypto');
+const EventEmitter = require('events');
+const { assert, refute, sinon } = require('@sinonjs/referee-sinon');
+const server = require('../lib/server');
+const linter = require('../lib/linter');
+const portfile = require('../lib/portfile');
+
+function createConnection() {
+  const connection = new EventEmitter();
+  connection.write = sinon.fake();
+  connection.end = sinon.fake();
+  return connection;
+}
+
+describe('server', () => {
+  const token = 'c2d003e2b9de9e70';
+  let net_server;
+  let connection;
+
+  beforeEach(() => {
+    net_server = new EventEmitter();
+    net_server.listen = sinon.fake();
+    net_server.close = sinon.fake();
+    net_server.address = sinon.fake.returns({ port: 8765 });
+    connection = createConnection();
+    sinon.replace(net, 'createServer', sinon.fake.returns(net_server));
+    sinon.replace(portfile, 'write', sinon.fake());
+    sinon.replace(crypto, 'randomBytes',
+      sinon.fake.returns(Buffer.from(token, 'hex')));
+  });
+
+  afterEach(() => {
+    sinon.restore();
+  });
+
+  function start() {
+    server.start();
+    net_server.listen.callback();
+  }
+
+  function connect(connection) {
+    net_server.emit('connection', connection);
+    net.createServer.callback(connection);
+  }
+
+  function request(connection, text) {
+    connect(connection);
+    if (text) {
+      connection.emit('data', text);
+    }
+    connection.emit('end');
+  }
+
+  it('starts server and listens on random port', () => {
+    const instance = server.start();
+
+    assert.equals(instance, net_server);
+    assert.calledOnceWith(net.createServer, {
+      allowHalfOpen: true
+    }, sinon.match.func);
+    assert.calledOnceWith(net_server.listen, 0, '127.0.0.1', sinon.match.func);
+  });
+
+  it('writes portfile when listen yields', () => {
+    server.start();
+
+    net_server.listen.callback();
+
+    assert.calledOnceWith(crypto.randomBytes, 8);
+    assert.calledOnceWith(portfile.write, 8765, token);
+  });
+
+  it('closes connection without writing anything for empty request', () => {
+    start();
+
+    request(connection);
+
+    refute.called(connection.write);
+    assert.calledOnce(connection.end);
+  });
+
+  describe('stop', () => {
+
+    it('closes connection and server for "stop" command', () => {
+      start();
+
+      request(connection, `${token} stop`);
+
+      refute.called(connection.write);
+      assert.calledOnce(connection.end);
+      assert.calledOnce(net_server.close);
+    });
+
+    it('closes any other pending connection on "stop" command', () => {
+      start();
+      const one = createConnection();
+      const two = createConnection();
+      connect(one);
+      connect(two);
+
+      request(connection, `${token} stop`);
+
+      assert.calledOnceWith(one.end, 'Server is stopping...\n# exit 1');
+      assert.calledOnceWith(two.end, 'Server is stopping...\n# exit 1');
+      assert.calledOnce(connection.end);
+      assert.calledWithExactly(connection.end);
+    });
+
+    it('ignores failures when attempting to close client connection', () => {
+      start();
+      const one = createConnection();
+      one.end = sinon.fake.throws(new Error());
+      const two = createConnection();
+      two.end = sinon.fake.throws(new Error());
+
+      connect(one);
+      connect(two);
+
+      request(connection, `${token} stop`);
+
+      assert.calledOnce(one.end);
+      assert.calledOnce(two.end);
+      assert.calledOnce(connection.end);
+      assert.calledOnce(net_server.close);
+    });
+
+    it('does not process "stop" if token is invalid', () => {
+      start();
+
+      request(connection, '123456789abcdef status');
+
+      assert.calledOnce(connection.end);
+      assert.calledWithExactly(connection.end);
+      refute.called(connection.write);
+      refute.called(net_server.close);
+    });
+
+  });
+
+  describe('status', () => {
+
+    it('prints linter status and closes connection', () => {
+      sinon.replace(linter, 'getStatus', sinon.fake.returns('Oh, hi!\n'));
+      start();
+
+      request(connection, `${token} status`);
+
+      assert.calledOnceWith(connection.end, 'Oh, hi!\n');
+    });
+
+    it('does not process "status" if token is invalid', () => {
+      sinon.replace(linter, 'getStatus', sinon.fake());
+      start();
+
+      request(connection, '123456789abcdef status');
+
+      assert.calledOnce(connection.end);
+      assert.calledWithExactly(connection.end);
+      refute.called(connection.write);
+      refute.called(linter.getStatus);
+    });
+
+  });
+
+  describe('lint', () => {
+    const json = {
+      cwd: '/some/path',
+      args: ['--some', '--args'],
+      text: '"Some text"'
+    };
+
+    it('invokes linter with JSON arguments', () => {
+      sinon.replace(linter, 'lint', sinon.fake.returns('Oh, hi!\n'));
+      start();
+
+      request(connection, `${token} ${JSON.stringify(json)}`);
+
+      assert.calledOnceWith(linter.lint, json.cwd, json.args, json.text);
+      assert.calledOnceWith(connection.write, 'Oh, hi!\n');
+      assert.calledOnce(connection.end);
+    });
+
+    it('invokes linter with plain text arguments', () => {
+      sinon.replace(linter, 'lint', sinon.fake.returns('Oh, hi!\n'));
+      start();
+
+      request(connection,
+        `${token} ${json.cwd} ${json.args.join(' ')}\n${json.text}`);
+
+      assert.calledOnceWith(linter.lint, json.cwd, json.args, json.text);
+      assert.calledOnceWith(connection.write, 'Oh, hi!\n');
+      assert.calledOnce(connection.end);
+    });
+
+    it('handles exception from linter', () => {
+      sinon.replace(linter, 'lint', sinon.fake.throws(new Error('Whatever')));
+      start();
+
+      request(connection, `${token} ${JSON.stringify(json)}`);
+
+      assert.calledOnceWith(connection.write, 'Error: Whatever\n# exit 1');
+      assert.calledOnce(connection.end);
+    });
+
+  });
+
+});