From c378b1885f5eb5f3f0f19f260511ae10ae18b866 Mon Sep 17 00:00:00 2001
From: Lars den Bakker <larsdenbakker@gmail.com>
Date: Wed, 27 Nov 2019 16:58:59 +0100
Subject: [PATCH] fix(fieldset): wait for registration before setting values

---
 packages/fieldset/src/LionFieldset.js        |  6 +++-
 packages/fieldset/test/lion-fieldset.test.js | 30 ++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/packages/fieldset/src/LionFieldset.js b/packages/fieldset/src/LionFieldset.js
index cfccbd53a..1f0395cf0 100644
--- a/packages/fieldset/src/LionFieldset.js
+++ b/packages/fieldset/src/LionFieldset.js
@@ -266,7 +266,11 @@ export class LionFieldset extends FormRegistrarMixin(
     });
   }
 
-  _setValueMapForAllFormElements(property, values) {
+  async _setValueMapForAllFormElements(property, values) {
+    if (!this.__readyForRegistration) {
+      await this.registrationReady;
+    }
+
     if (values && typeof values === 'object') {
       Object.keys(values).forEach(name => {
         if (Array.isArray(this.formElements[name])) {
diff --git a/packages/fieldset/test/lion-fieldset.test.js b/packages/fieldset/test/lion-fieldset.test.js
index fa71b2b0d..c39dc9264 100644
--- a/packages/fieldset/test/lion-fieldset.test.js
+++ b/packages/fieldset/test/lion-fieldset.test.js
@@ -248,6 +248,36 @@ describe('<lion-fieldset>', () => {
     expect(el.formElements.sub.formElements['hobbies[]'][1].disabled).to.be.true;
   });
 
+  it('can set initial modelValue on creation', async () => {
+    const initialModelValue = {
+      lastName: 'Bar',
+    };
+    const el = await fixture(html`
+      <${tag} .modelValue=${initialModelValue}>
+        <${childTag} name="lastName"></${childTag}>
+      </${tag}>
+    `);
+
+    await el.registrationReady;
+    await el.updateComplete;
+    expect(el.modelValue).to.eql(initialModelValue);
+  });
+
+  it('can set initial serializedValue on creation', async () => {
+    const initialSerializedValue = {
+      lastName: 'Bar',
+    };
+    const el = await fixture(html`
+      <${tag} .modelValue=${initialSerializedValue}>
+        <${childTag} name="lastName"></${childTag}>
+      </${tag}>
+    `);
+
+    await el.registrationReady;
+    await el.updateComplete;
+    expect(el.modelValue).to.eql(initialSerializedValue);
+  });
+
   describe('validation', () => {
     it('validates on init', async () => {
       class IsCat extends Validator {