diff --git a/src/__tests__/index.js b/src/__tests__/index.js
index 20683ea3..3bcd728c 100644
--- a/src/__tests__/index.js
+++ b/src/__tests__/index.js
@@ -18,8 +18,7 @@ test('simulate render request', async t => {
   const renderFn = () => {
     flags.render = true;
   };
-  const app = new App(element, renderFn);
-  var testApp = getSimulator(app);
+  var testApp = getSimulator(() => new App(element, renderFn));
   const ctx = await testApp.render('/');
   t.ok(flags.render, 'triggered ssr');
   t.ok(ctx.element, 'sets ctx.element');
@@ -31,8 +30,7 @@ test('simulate multi-render requests', async t => {
   const renderFn = () => {
     counter.renderCount++;
   };
-  const app = new App('hello', renderFn);
-  var testApp = getSimulator(app);
+  var testApp = getSimulator(() => new App('hello', renderFn));
 
   for (var i = 1; i <= 5; i++) {
     await testApp.render('/');
@@ -48,8 +46,7 @@ test('simulate non-render request', async t => {
   const renderFn = () => {
     flags.render = true;
   };
-  const app = new App(element, renderFn);
-  const testApp = getSimulator(app);
+  const testApp = getSimulator(() => new App(element, renderFn));
   if (__BROWSER__) {
     try {
       testApp.request('/');
@@ -86,7 +83,6 @@ test('use simulator with fixture and plugin dependencies', async t => {
     app.register(msgProviderPluginToken, msgProviderPlugin);
     return app;
   }
-  const app = getTestFixture();
 
   t.plan(3);
   let testPlugin: FusionPlugin<*, *> = createPlugin({
@@ -105,7 +101,7 @@ test('use simulator with fixture and plugin dependencies', async t => {
       return 'yay!';
     },
   });
-  getSimulator(app, testPlugin);
+  getSimulator(getTestFixture, testPlugin);
 
   t.end();
 });
diff --git a/src/__tests__/index.node.js b/src/__tests__/index.node.js
index ce580e0d..c2e099cf 100644
--- a/src/__tests__/index.node.js
+++ b/src/__tests__/index.node.js
@@ -12,49 +12,58 @@ import App from 'fusion-core';
 import {getSimulator} from '../index.js';
 
 test('status is 404 if ctx.body is never updated', async t => {
-  const app = new App('el', el => el);
-  const ctx = await getSimulator(app).request('/');
+  const ctx = await getSimulator(() => new App('el', el => el)).request('/');
   t.equals(ctx.status, 404, 'status defaults to 404');
   t.end();
 });
 
 test('status is 200 if ctx.body is updated in request', async t => {
-  const app = new App('el', el => el);
-  app.middleware((ctx, next) => {
-    ctx.body = {ok: 1};
-    return next();
-  });
-  const ctx = await getSimulator(app).request('/');
+  const appCreator = () => {
+    const app = new App('el', el => el);
+    app.middleware((ctx, next) => {
+      ctx.body = {ok: 1};
+      return next();
+    });
+    return app;
+  };
+  const ctx = await getSimulator(appCreator).request('/');
   t.equals(ctx.status, 200, 'status defaults to 200');
   t.end();
 });
 
 test('status is set if ctx.status is updated in request', async t => {
-  const app = new App('el', () => 'hello');
-  app.middleware((ctx, next) => {
-    ctx.status = 500;
-    ctx.body = {error: 'error'};
-    return next();
-  });
-  const ctx = await getSimulator(app).render('/');
+  const appCreator = () => {
+    const app = new App('el', () => 'hello');
+    app.middleware((ctx, next) => {
+      ctx.status = 500;
+      ctx.body = {error: 'error'};
+      return next();
+    });
+    return app;
+  };
+  const ctx = await getSimulator(appCreator).render('/');
   t.equals(ctx.status, 500, 'status is set');
   t.end();
 });
 
 test('status is 200 if ctx.body is updated in render', async t => {
-  const app = new App('el', () => 'hello');
-  const ctx = await getSimulator(app).render('/');
+  const ctx = await getSimulator(() => new App('el', () => 'hello')).render(
+    '/'
+  );
   t.equals(ctx.status, 200, 'status defaults to 200');
   t.end();
 });
 
 test('status is set if ctx.status is updated in render', async t => {
-  const app = new App('el', () => 'hello');
-  app.middleware((ctx, next) => {
-    ctx.status = 500;
-    return next();
-  });
-  const ctx = await getSimulator(app).render('/');
+  const appCreator = () => {
+    const app = new App('el', () => 'hello');
+    app.middleware((ctx, next) => {
+      ctx.status = 500;
+      return next();
+    });
+    return app;
+  };
+  const ctx = await getSimulator(appCreator).render('/');
   t.equals(ctx.status, 500, 'status is set');
   t.end();
 });
diff --git a/src/index.js b/src/index.js
index 8d3571f9..cb14281e 100644
--- a/src/index.js
+++ b/src/index.js
@@ -27,10 +27,12 @@ export type Simulator = {
   request: $Call<ExtractFusionAppReturnType, typeof request>,
   render: $Call<ExtractFusionAppReturnType, typeof render>,
 };
-export function getSimulator(
-  app: FusionApp,
-  testPlugin?: FusionPlugin<*, *>
+export function getSimulator<TDeps, TService>(
+  appCreator: () => FusionApp,
+  testPlugin?: FusionPlugin<TDeps, TService>
 ): Simulator {
+  const app = appCreator();
+
   if (testPlugin) {
     app.register(testPlugin);
   }