diff --git a/doc/qweb.md b/doc/qweb.md
index 942158fe..3e997093 100644
--- a/doc/qweb.md
+++ b/doc/qweb.md
@@ -497,10 +497,10 @@ directive is there to help.
 Whenever a node has a `t-transition` directive, with a `name` value, the following
 will happen:
 
-At node creation:
+At node insertion:
 
-- the css classes `name-enter` and `name-enter-active` will be added before the
-  node is added to the DOM,
+- the css classes `name-enter` and `name-enter-active` will be added directly
+  when the node is inserted into the DOM,
 - on the next animation frame: the css class `name-enter` will be removed and the
   class `name-enter-to` will be added (so they can be used to trigger css
   transition effects),
@@ -535,6 +535,8 @@ For example, a simple fade in/out effect can be done with this:
 }
 ```
 
+The `t-transition` directive can be combined with `t-widget`.
+
 Note: more information on animations are available [here](doc/animations.md).
 
 ### `t-mounted` directive
diff --git a/src/qweb_core.ts b/src/qweb_core.ts
index fc417d4c..5376db42 100644
--- a/src/qweb_core.ts
+++ b/src/qweb_core.ts
@@ -269,6 +269,9 @@ export class QWeb {
       // pollute the rendering context by adding some keys in it.
       ctx.code.unshift("    let owner = context;");
     }
+    if (ctx.shouldDefineUtils) {
+      ctx.code.unshift("    let utils = this.utils;");
+    }
 
     if (!ctx.rootNode) {
       throw new Error("A template should have one root node");
@@ -613,6 +616,7 @@ export class Context {
   rootContext: Context;
   caller: Element | undefined;
   shouldDefineOwner: boolean = false;
+  shouldDefineUtils: boolean = false;
   shouldProtectContext: boolean = false;
   inLoop: boolean = false;
   inPreTag: boolean = false;
diff --git a/src/qweb_extensions.ts b/src/qweb_extensions.ts
index 712612b4..8660504c 100644
--- a/src/qweb_extensions.ts
+++ b/src/qweb_extensions.ts
@@ -192,7 +192,10 @@ QWeb.addDirective({
  * explanation of the code generated by the t-widget directive for the following
  * situation:
  * ```xml
- *   <t t-widget="child" t-key="'somestring'" t-props="{flag:state.flag}"/>
+ *   <t t-widget="child"
+ *      t-key="'somestring'"
+ *      t-props="{flag:state.flag}"
+ *      t-transition="fade"/>
  * ```
  *
  * ```js
@@ -252,6 +255,8 @@ QWeb.addDirective({
  *   }
  *   w4 = new W4(owner, props4);
  *
+ *   let utils = this.utils;
+ *
  *   // Whenever we rerender the parent widget, we need to be sure that we
  *   // are able to find the widget instance. To do that, we register it to
  *   // the parent cmap (children map).  Note that the 'template' key is
@@ -281,15 +286,21 @@ QWeb.addDirective({
  *         // to synchronise the pvnode elm with the resulting elm
  *         let nvn = w4._mount(vnode, vn.elm);
  *         pvnode.elm = nvn.elm;
+ *         // what follows is only present if there are animations on the widget
+ *         utils.transitionInsert(vn.elm, "fade");
  *       },
  *       remove() {
- *         // apparently, in some cases, it is necessary to call the destroy
- *         // method here
- *         w4.destroy();
+ *         // override with empty function to prevent from removing the node
+ *         // directly. It will be removed when destroy is called anyway, which
+ *         // delays the removal if there are animations.
  *       },
  *       destroy() {
- *         // and here...
- *         w4.destroy();
+ *         // if there are animations, we delay the call to destroy on the
+ *         // widget, if not, we call it directly.
+ *         let finalize = () => {
+ *           w4.destroy();
+ *         };
+ *         utils.transitionRemove(vn.elm, "fade", finalize);
  *       }
  *     };
  *     // the pvnode is inserted at the correct position in the div's children
@@ -332,16 +343,20 @@ QWeb.addDirective({
   atNodeEncounter({ ctx, value, node }): boolean {
     ctx.addLine("//WIDGET");
     ctx.rootContext.shouldDefineOwner = true;
+    ctx.rootContext.shouldDefineUtils = true;
     let props = node.getAttribute("t-props");
     let keepAlive = node.getAttribute("t-keepalive") ? true : false;
 
-    // t-on- events...
+    // t-on- events and t-transition
     const events: [string, string][] = [];
+    let transition: string = "";
     const attributes = (<Element>node).attributes;
     for (let i = 0; i < attributes.length; i++) {
       const name = attributes[i].name;
       if (name.startsWith("t-on-")) {
         events.push([name.slice(5), attributes[i].textContent!]);
+      } else if (name === "t-transition") {
+        transition = attributes[i].textContent!;
       }
     }
 
@@ -378,13 +393,23 @@ QWeb.addDirective({
       ctx.addLine(`const ${refKey} = ${ctx.formatExpression(ref)}`);
       refExpr = `context.refs[${refKey}] = w${widgetID};`;
     }
-
+    let transitionsInsertCode = "";
+    if (transition) {
+      transitionsInsertCode = `utils.transitionInsert(vn.elm, '${transition}');`;
+    }
     let finalizeWidgetCode = `w${widgetID}.${
       keepAlive ? "unmount" : "destroy"
-    }()`;
+    }();`;
     if (ref) {
-      finalizeWidgetCode += `;delete context.refs[${refKey}]`;
+      finalizeWidgetCode += `delete context.refs[${refKey}];`; // FIXME: shouldn't we keep ref if keepAlive is true?
     }
+    if (transition) {
+      finalizeWidgetCode = `let finalize = () => {
+          ${finalizeWidgetCode}
+        };
+        utils.transitionRemove(vn.elm, '${transition}', finalize);`;
+    }
+
     let createHook = "";
     let classAttr = node.getAttribute("class");
     let tattClass = node.getAttribute("t-att-class");
@@ -447,8 +472,10 @@ QWeb.addDirective({
       ctx.addLine(`w${widgetID}.on('${event}', owner, owner['${method}'])`);
     }
     ctx.addLine(`def${defID} = w${widgetID}._prepare();`);
+    // hack: specify empty remove hook to prevent the node from being removed from the DOM
+    // FIXME: click to re-add widget during remove transition -> leak
     ctx.addLine(
-      `def${defID} = def${defID}.then(vnode=>{${createHook}let pvnode=h(vnode.sel, {key: ${templateID}, hook: {insert(vn){let nvn=w${widgetID}._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;${refExpr}},remove(){${finalizeWidgetCode}},destroy(){${finalizeWidgetCode}}}});c${
+      `def${defID} = def${defID}.then(vnode=>{${createHook}let pvnode=h(vnode.sel, {key: ${templateID}, hook: {insert(vn) {let nvn=w${widgetID}._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;${refExpr}${transitionsInsertCode}},remove() {},destroy(vn) {${finalizeWidgetCode}}}});c${
         ctx.parentNode
       }[_${dummyID}_index]=pvnode;w${widgetID}.__owl__.pvnode = pvnode;});`
     );
diff --git a/tests/__snapshots__/component.test.ts.snap b/tests/__snapshots__/component.test.ts.snap
index 57841099..f07dba6b 100644
--- a/tests/__snapshots__/component.test.ts.snap
+++ b/tests/__snapshots__/component.test.ts.snap
@@ -1,8 +1,85 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`animations t-transition combined with t-widget 1`] = `
+"function anonymous(context,extra
+) {
+    let utils = this.utils;
+    let owner = context;
+    var h = this.utils.h;
+    let c1 = [], p1 = {key:1};
+    var vn1 = h('div', p1, c1);
+    //WIDGET
+    let _2_index = c1.length;
+    c1.push(null);
+    let def3;
+    let w4 = 4 in context.__owl__.cmap ? context.__owl__.children[context.__owl__.cmap[4]] : false;
+    let props4 = {};
+    if (w4 && w4.__owl__.renderPromise && !w4.__owl__.vnode && props4 !== w4.__owl__.renderProps) {
+        w4.destroy();
+        w4 = false
+    }
+    if (!w4) {
+        let W4 = context.widgets['Child'];
+        if (!W4) {throw new Error(\`Cannot find the definition of widget \\"Child\\"\`)}
+        w4 = new W4(owner, props4);
+        context.__owl__.cmap[4] = w4.__owl__.id;
+        def3 = w4._prepare();
+        def3 = def3.then(vnode=>{let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn) {let nvn=w4._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;utils.transitionInsert(vn.elm, 'chimay');},remove() {},destroy(vn) {let finalize = () => {
+          w4.destroy();
+        };
+        utils.transitionRemove(vn.elm, 'chimay', finalize);}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
+    } else {
+        def3 = w4._updateProps(props4, extra.forceUpdate, extra.patchQueue);
+        def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
+    }
+    extra.promises.push(def3);
+    return vn1;
+}"
+`;
+
+exports[`animations t-transition combined with t-widget and t-if 1`] = `
+"function anonymous(context,extra
+) {
+    let utils = this.utils;
+    let owner = context;
+    var h = this.utils.h;
+    let c1 = [], p1 = {key:1};
+    var vn1 = h('div', p1, c1);
+    if (context['state'].display) {
+        //WIDGET
+        let _2_index = c1.length;
+        c1.push(null);
+        let def3;
+        let w4 = 4 in context.__owl__.cmap ? context.__owl__.children[context.__owl__.cmap[4]] : false;
+        let props4 = {};
+        if (w4 && w4.__owl__.renderPromise && !w4.__owl__.vnode && props4 !== w4.__owl__.renderProps) {
+            w4.destroy();
+            w4 = false
+        }
+        if (!w4) {
+            let W4 = context.widgets['Child'];
+            if (!W4) {throw new Error(\`Cannot find the definition of widget \\"Child\\"\`)}
+            w4 = new W4(owner, props4);
+            context.__owl__.cmap[4] = w4.__owl__.id;
+            def3 = w4._prepare();
+            def3 = def3.then(vnode=>{let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn) {let nvn=w4._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;utils.transitionInsert(vn.elm, 'chimay');},remove() {},destroy(vn) {let finalize = () => {
+          w4.destroy();
+        };
+        utils.transitionRemove(vn.elm, 'chimay', finalize);}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
+        } else {
+            def3 = w4._updateProps(props4, extra.forceUpdate, extra.patchQueue);
+            def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
+        }
+        extra.promises.push(def3);
+    }
+    return vn1;
+}"
+`;
+
 exports[`class and style attributes with t-widget dynamic t-att-style is properly added and updated on widget root el 1`] = `
 "function anonymous(context,extra
 ) {
+    let utils = this.utils;
     let owner = context;
     var h = this.utils.h;
     let c1 = [], p1 = {key:1};
@@ -24,7 +101,7 @@ exports[`class and style attributes with t-widget dynamic t-att-style is properl
         w4 = new W4(owner, props4);
         context.__owl__.cmap[4] = w4.__owl__.id;
         def3 = w4._prepare();
-        def3 = def3.then(vnode=>{vnode.data.hook = {create(_, vn){vn.elm.style = _5}};let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn){let nvn=w4._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove(){w4.destroy()},destroy(){w4.destroy()}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
+        def3 = def3.then(vnode=>{vnode.data.hook = {create(_, vn){vn.elm.style = _5}};let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn) {let nvn=w4._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w4.destroy();}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
     } else {
         def3 = w4._updateProps(props4, extra.forceUpdate, extra.patchQueue);
         def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};w4.el.style=_5;let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
@@ -37,6 +114,7 @@ exports[`class and style attributes with t-widget dynamic t-att-style is properl
 exports[`class and style attributes with t-widget t-att-class is properly added/removed on widget root el 1`] = `
 "function anonymous(context,extra
 ) {
+    let utils = this.utils;
     let owner = context;
     var h = this.utils.h;
     let c1 = [], p1 = {key:1};
@@ -62,7 +140,7 @@ exports[`class and style attributes with t-widget t-att-class is properly added/
               if (_5[k]) {
                   vn.elm.classList.add(k);
               }
-          }}};let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn){let nvn=w4._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove(){w4.destroy()},destroy(){w4.destroy()}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
+          }}};let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn) {let nvn=w4._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w4.destroy();}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
     } else {
         def3 = w4._updateProps(props4, extra.forceUpdate, extra.patchQueue);
         def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let cl=w4.el.classList;for (let k in _5) {if (_5[k]) {cl.add(k)} else {cl.remove(k)}}let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
@@ -75,6 +153,7 @@ exports[`class and style attributes with t-widget t-att-class is properly added/
 exports[`composition sub widgets with some state rendered in a loop 1`] = `
 "function anonymous(context,extra
 ) {
+    let utils = this.utils;
     let owner = context;
     context = Object.create(context);
     var h = this.utils.h;
@@ -109,7 +188,7 @@ exports[`composition sub widgets with some state rendered in a loop 1`] = `
             w7 = new W7(owner, props7);
             context.__owl__.cmap[key8] = w7.__owl__.id;
             def6 = w7._prepare();
-            def6 = def6.then(vnode=>{let pvnode=h(vnode.sel, {key: key8, hook: {insert(vn){let nvn=w7._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove(){w7.destroy()},destroy(){w7.destroy()}}});c1[_5_index]=pvnode;w7.__owl__.pvnode = pvnode;});
+            def6 = def6.then(vnode=>{let pvnode=h(vnode.sel, {key: key8, hook: {insert(vn) {let nvn=w7._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w7.destroy();}}});c1[_5_index]=pvnode;w7.__owl__.pvnode = pvnode;});
         } else {
             def6 = w7._updateProps(props7, extra.forceUpdate, extra.patchQueue);
             def6 = def6.then(()=>{if (w7.__owl__.isDestroyed) {return};let pvnode=w7.__owl__.pvnode;c1[_5_index]=pvnode;});
@@ -123,6 +202,7 @@ exports[`composition sub widgets with some state rendered in a loop 1`] = `
 exports[`random stuff/miscellaneous snapshotting compiled code 1`] = `
 "function anonymous(context,extra
 ) {
+    let utils = this.utils;
     let owner = context;
     var h = this.utils.h;
     let c1 = [], p1 = {key:1};
@@ -144,7 +224,7 @@ exports[`random stuff/miscellaneous snapshotting compiled code 1`] = `
         w4 = new W4(owner, props4);
         context.__owl__.cmap[key5] = w4.__owl__.id;
         def3 = w4._prepare();
-        def3 = def3.then(vnode=>{let pvnode=h(vnode.sel, {key: key5, hook: {insert(vn){let nvn=w4._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove(){w4.destroy()},destroy(){w4.destroy()}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
+        def3 = def3.then(vnode=>{let pvnode=h(vnode.sel, {key: key5, hook: {insert(vn) {let nvn=w4._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w4.destroy();}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
     } else {
         def3 = w4._updateProps(props4, extra.forceUpdate, extra.patchQueue);
         def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
@@ -157,6 +237,7 @@ exports[`random stuff/miscellaneous snapshotting compiled code 1`] = `
 exports[`random stuff/miscellaneous t-props should not be undefined (snapshotting) 1`] = `
 "function anonymous(context,extra
 ) {
+    let utils = this.utils;
     let owner = context;
     var h = this.utils.h;
     let c1 = [], p1 = {key:1};
@@ -177,7 +258,7 @@ exports[`random stuff/miscellaneous t-props should not be undefined (snapshottin
         w4 = new W4(owner, props4);
         context.__owl__.cmap[4] = w4.__owl__.id;
         def3 = w4._prepare();
-        def3 = def3.then(vnode=>{let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn){let nvn=w4._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove(){w4.destroy()},destroy(){w4.destroy()}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
+        def3 = def3.then(vnode=>{let pvnode=h(vnode.sel, {key: 4, hook: {insert(vn) {let nvn=w4._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;},remove() {},destroy(vn) {w4.destroy();}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
     } else {
         def3 = w4._updateProps(props4, extra.forceUpdate, extra.patchQueue);
         def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
diff --git a/tests/__snapshots__/untitled.js b/tests/__snapshots__/untitled.js
new file mode 100644
index 00000000..b1409550
--- /dev/null
+++ b/tests/__snapshots__/untitled.js
@@ -0,0 +1,33 @@
+function anonymous(context, extra) {
+ var h = this.utils.h;
+          let c1 = [], p1 = {key:1};
+          var vn1 = h('div', p1, c1);
+          if (context['state'].display) {
+              //WIDGET
+              let _2_index = c1.length;
+              c1.push(null);
+              let def3;
+              let w4 = 4 in context.__owl__.cmap ? context.__owl__.children[context.__owl__.cmap[4]] : false;
+              let props4 = {};
+              if (w4 && w4.__owl__.renderPromise && !w4.__owl__.vnode && props4 !== w4.__owl__.renderProps) {
+                  w4.destroy();
+                  w4 = false
+              }
+              if (!w4) {
+                  let W4 = context.widgets['Child'];
+                  if (!W4) {throw new Error(`Cannot find the definition of widget "Child"`)}
+                  w4 = new W4(owner, props4);
+                  context.__owl__.cmap[4] = w4.__owl__.id;
+                  def3 = w4._prepare();
+                  def3 = def3.then(vnode=>{let pvnode=h(vnode.sel, {key: 4, hook: {insert: (vn) => {let nvn=w4._mount(vnode, pvnode.elm);pvnode.elm=nvn.elm;this.utils.transitionInsert(vn.elm, 'chimay');},remove: () => {},destroy: (vn) => {let finalize = () => {
+                w4.destroy();
+              };
+              this.utils.transitionRemove(vn.elm, 'chimay', finalize);}}});c1[_2_index]=pvnode;w4.__owl__.pvnode = pvnode;});
+              } else {
+                  def3 = w4._updateProps(props4, extra.forceUpdate, extra.patchQueue);
+                  def3 = def3.then(()=>{if (w4.__owl__.isDestroyed) {return};let pvnode=w4.__owl__.pvnode;c1[_2_index]=pvnode;});
+              }
+              extra.promises.push(def3);
+          }
+
+}
diff --git a/tests/component.test.ts b/tests/component.test.ts
index cd7addef..d40f715a 100644
--- a/tests/component.test.ts
+++ b/tests/component.test.ts
@@ -1778,7 +1778,6 @@ describe("random stuff/miscellaneous", () => {
       "C:_patch",
       "E:willUnmount",
       "E:destroy",
-      "E:destroy", // maybe should look into this
       "F:_patch(from _mount)",
       "F:mounted",
       "D:_patch",
@@ -2281,7 +2280,7 @@ describe("t-mounted directive", () => {
     widget.f = jest.fn();
     await widget.mount(fixture);
 
-    patchNextFrame((cb) => cb());
+    patchNextFrame(cb => cb());
     expect(widget.f).toHaveBeenCalledTimes(0);
 
     widget.state.flag = true;
@@ -2426,4 +2425,100 @@ describe("animations", () => {
     spanNode.dispatchEvent(new Event("transitionend")); // mock end of css transition
     expect(spanNode.className).toBe("");
   });
+
+  test("t-transition combined with t-widget", async () => {
+    expect.assertions(5);
+
+    env.qweb.addTemplate(
+      "Parent",
+      `<div><t t-widget="Child" t-transition="chimay"/></div>`
+    );
+    env.qweb.addTemplate("Child", `<span>blue</span>`);
+    class Parent extends Widget {
+      widgets = { Child: Child };
+    }
+    class Child extends Widget {}
+    const widget = new Parent(env);
+
+    let def = makeDeferred();
+    var spanNode;
+    patchNextFrame(cb => {
+      expect(fixture.innerHTML).toBe(
+        '<div><span class="chimay-enter chimay-enter-active">blue</span></div>'
+      );
+      cb(performance.now());
+      expect(fixture.innerHTML).toBe(
+        '<div><span class="chimay-enter-active chimay-enter-to">blue</span></div>'
+      );
+      def.resolve();
+    });
+    await widget.mount(fixture);
+    spanNode = widget.el!.children[0];
+
+    expect(env.qweb.templates.Parent.fn.toString()).toMatchSnapshot();
+    expect(fixture.innerHTML).toBe(
+      '<div><span class="chimay-enter chimay-enter-active">blue</span></div>'
+    );
+
+    await def; // wait for the mocked repaint to be done
+    spanNode.dispatchEvent(new Event("transitionend")); // mock end of css transition
+    expect(fixture.innerHTML).toBe('<div><span class="">blue</span></div>');
+  });
+
+  test("t-transition combined with t-widget and t-if", async () => {
+    expect.assertions(8);
+
+    env.qweb.addTemplate(
+      "Parent",
+      `<div><t t-if="state.display" t-widget="Child" t-transition="chimay"/></div>`
+    );
+    env.qweb.addTemplate("Child", `<span>blue</span>`);
+    class Parent extends Widget {
+      widgets = { Child: Child };
+      state = { display: true };
+    }
+    class Child extends Widget {}
+    const widget = new Parent(env);
+
+    let def = makeDeferred();
+    var spanNode;
+    patchNextFrame(cb => {
+      expect(fixture.innerHTML).toBe(
+        '<div><span class="chimay-enter chimay-enter-active">blue</span></div>'
+      );
+      cb(performance.now());
+      expect(fixture.innerHTML).toBe(
+        '<div><span class="chimay-enter-active chimay-enter-to">blue</span></div>'
+      );
+      def.resolve();
+    });
+    await widget.mount(fixture);
+    spanNode = widget.el!.children[0];
+
+    expect(env.qweb.templates.Parent.fn.toString()).toMatchSnapshot();
+    expect(fixture.innerHTML).toBe(
+      '<div><span class="chimay-enter chimay-enter-active">blue</span></div>'
+    );
+
+    await def; // wait for the mocked repaint to be done
+    spanNode.dispatchEvent(new Event("transitionend")); // mock end of css transition
+    expect(fixture.innerHTML).toBe('<div><span class="">blue</span></div>');
+
+    // remove span from the DOM
+    def = makeDeferred();
+    widget.state.display = false;
+    patchNextFrame(cb => {
+      expect(fixture.innerHTML).toBe(
+        '<div><span class="chimay-leave chimay-leave-active">blue</span></div>'
+      );
+      cb(performance.now());
+      expect(fixture.innerHTML).toBe(
+        '<div><span class="chimay-leave-active chimay-leave-to">blue</span></div>'
+      );
+      def.resolve();
+    });
+    await def; // wait for the mocked repaint to be done
+    spanNode.dispatchEvent(new Event("transitionend")); // mock end of css transition
+    expect(fixture.innerHTML).toBe("<div></div>");
+  });
 });