diff --git a/package.json b/package.json
index 5c9e1a74..d5303b1b 100644
--- a/package.json
+++ b/package.json
@@ -39,6 +39,7 @@
     "jest-environment-jsdom": "^24.7.1",
     "live-server": "^1.2.1",
     "npm-run-all": "^4.1.5",
+    "prettier": "^1.19.1",
     "rollup": "^1.6.0",
     "rollup-plugin-typescript2": "^0.20.1",
     "sass": "^1.16.1",
diff --git a/src/vdom/vdom.ts b/src/vdom/vdom.ts
index f7731e19..58845c3e 100644
--- a/src/vdom/vdom.ts
+++ b/src/vdom/vdom.ts
@@ -101,7 +101,7 @@ function isVnode(vnode: any): vnode is VNode {
 
 type KeyToIndexMap = { [key: string]: number };
 
-type ArraysOf<T> = { [K in keyof T]: (T[K])[] };
+type ArraysOf<T> = { [K in keyof T]: T[K][] };
 
 type ModuleHooks = ArraysOf<Module>;
 
diff --git a/tests/component/component.test.ts b/tests/component/component.test.ts
index 87aa49c1..4a814f13 100644
--- a/tests/component/component.test.ts
+++ b/tests/component/component.test.ts
@@ -1362,7 +1362,13 @@ describe("composition", () => {
     class SubWidget extends Widget {}
     class Parent extends Widget {
       static components = { SubWidget };
-      state = useState({ blips: [{ a: "a", id: 1 }, { b: "b", id: 2 }, { c: "c", id: 4 }] });
+      state = useState({
+        blips: [
+          { a: "a", id: 1 },
+          { b: "b", id: 2 },
+          { c: "c", id: 4 }
+        ]
+      });
     }
     const parent = new Parent();
     await parent.mount(fixture);
@@ -1465,7 +1471,11 @@ describe("composition", () => {
             </t>
           </div>`;
       state = useState({
-        records: [{ id: 1, val: 1 }, { id: 2, val: 2 }, { id: 3, val: 3 }]
+        records: [
+          { id: 1, val: 1 },
+          { id: 2, val: 2 },
+          { id: 3, val: 3 }
+        ]
       });
       static components = { ChildWidget };
     }
@@ -3731,7 +3741,12 @@ describe("t-slot directive", () => {
     class Link extends Widget {}
 
     class App extends Widget {
-      state = useState({ users: [{ id: 1, name: "Aaron" }, { id: 2, name: "David" }] });
+      state = useState({
+        users: [
+          { id: 1, name: "Aaron" },
+          { id: 2, name: "David" }
+        ]
+      });
       static components = { Link };
     }
 
@@ -3770,7 +3785,12 @@ describe("t-slot directive", () => {
     class Link extends Widget {}
 
     class App extends Widget {
-      state = useState({ users: [{ id: 1, name: "Aaron" }, { id: 2, name: "David" }] });
+      state = useState({
+        users: [
+          { id: 1, name: "Aaron" },
+          { id: 2, name: "David" }
+        ]
+      });
       static components = { Link };
     }
 
@@ -4406,7 +4426,11 @@ describe("t-model directive", () => {
           </t>
         </div>
       `;
-      state = useState([{ f: false, id: 1 }, { f: false, id: 2 }, { f: false, id: 3 }]);
+      state = useState([
+        { f: false, id: 1 },
+        { f: false, id: 2 },
+        { f: false, id: 3 }
+      ]);
     }
     const comp = new SomeComponent();
     await comp.mount(fixture);
diff --git a/tests/qweb/qweb.test.ts b/tests/qweb/qweb.test.ts
index d384778c..d1d85c4b 100644
--- a/tests/qweb/qweb.test.ts
+++ b/tests/qweb/qweb.test.ts
@@ -1225,7 +1225,10 @@ describe("t-on", () => {
     );
     const steps: string[] = [];
     const owner = {
-      projects: [{ id: 1, name: "Project 1" }, { id: 2, name: "Project 2" }],
+      projects: [
+        { id: 1, name: "Project 1" },
+        { id: 2, name: "Project 2" }
+      ],
 
       onEdit(projectId, ev) {
         expect(ev.defaultPrevented).toBe(true);
diff --git a/tests/qweb/qweb_expressions.test.ts b/tests/qweb/qweb_expressions.test.ts
index 7ea57d1a..99d9bbf1 100644
--- a/tests/qweb/qweb_expressions.test.ts
+++ b/tests/qweb/qweb_expressions.test.ts
@@ -27,7 +27,10 @@ describe("tokenizer", () => {
       { type: "VALUE", value: "2" },
       { type: "RIGHT_BRACE", value: "}" }
     ]);
-    expect(tokenize("a,")).toEqual([{ type: "SYMBOL", value: "a" }, { type: "COMMA", value: "," }]);
+    expect(tokenize("a,")).toEqual([
+      { type: "SYMBOL", value: "a" },
+      { type: "COMMA", value: "," }
+    ]);
     expect(tokenize("][")).toEqual([
       { type: "RIGHT_BRACKET", value: "]" },
       { type: "LEFT_BRACKET", value: "[" }
diff --git a/tests/router/link.test.ts b/tests/router/link.test.ts
index 74bf7c73..f8df5c53 100644
--- a/tests/router/link.test.ts
+++ b/tests/router/link.test.ts
@@ -35,7 +35,10 @@ describe("Link component", () => {
       static components = { Link: Link };
     }
 
-    const routes = [{ name: "about", path: "/about" }, { name: "users", path: "/users" }];
+    const routes = [
+      { name: "about", path: "/about" },
+      { name: "users", path: "/users" }
+    ];
 
     router = new TestRouter(env, routes, { mode: "history" });
     router.navigate({ to: "users" });
@@ -66,7 +69,10 @@ describe("Link component", () => {
       static components = { Link: Link };
     }
 
-    const routes = [{ name: "about", path: "/about" }, { name: "users", path: "/users" }];
+    const routes = [
+      { name: "about", path: "/about" },
+      { name: "users", path: "/users" }
+    ];
 
     router = new TestRouter(env, routes, { mode: "history" });
     router.navigate({ to: "users" });
diff --git a/tests/store_hooks.test.ts b/tests/store_hooks.test.ts
index 968cef53..d181d2f0 100644
--- a/tests/store_hooks.test.ts
+++ b/tests/store_hooks.test.ts
@@ -293,7 +293,12 @@ describe("connecting a component to store", () => {
   });
 
   test("useStore can use props", async () => {
-    const state = { todos: [{ id: 1, text: "jupiler" }, { id: 2, text: "chimay" }] };
+    const state = {
+      todos: [
+        { id: 1, text: "jupiler" },
+        { id: 2, text: "chimay" }
+      ]
+    };
     const store = new Store({ state, actions: {} });
 
     class TodoItem extends Component<any, any> {
@@ -360,7 +365,10 @@ describe("connecting a component to store", () => {
   test("can call useGetters to receive store getters", async () => {
     const state = {
       importantID: 1,
-      todos: [{ id: 1, text: "jupiler" }, { id: 2, text: "bertinchamps" }]
+      todos: [
+        { id: 1, text: "jupiler" },
+        { id: 2, text: "bertinchamps" }
+      ]
     };
     const getters = {
       importantTodoText({ state }) {