[FIX] web_editor: discard changes html field

Issue:
======
Discard changes of form having html field doesn't remove the changes
applied in the html field.

Steps to reproduce the issue:
=============================
- Open any mail template
- Add modification on the template
- Click on discard changes

Origin of the issue:
====================
The function `this.props.update` is responsible of updating `_changes`
and updating the record which is called for usual input_field using
`useInputField` hook, but since this html field isn't of the same format
we didn't use it and it's only called in `commitChanges`

Solution:
=========
We update the value of in `_onWysiwygBlur` in case we are `inlineStyle`
so we don't commit but we save the changes for the discard to work
properly.

task-3453497

closes #149601

Signed-off-by: Antoine Guenet (age) <age@odoo.com>

addons/web_editor/static/src/js/backend/html_field.js

@@ -590,7 +590,9 @@ export class HtmlField extends Component {
     }
     _onWysiwygBlur() {
         // Avoid save on blur if the html field is in inline mode.
-        if (!this.props.isInlineStyle) {
+        if (this.props.isInlineStyle) {
+            this.updateValue();
+        } else {
             this.commitChanges();
         }
     }

addons/web_editor/static/tests/html_field_tests.js

@@ -9,6 +9,7 @@ import { MediaDialog } from "@web_editor/components/media_dialog/media_dialog";
 import { parseHTML, setSelection } from "@web_editor/js/editor/odoo-editor/src/utils/utils";
 import { onRendered } from "@odoo/owl";
 import { wysiwygData } from "web_editor.test_utils";
+import { insertText } from '@web_editor/js/editor/odoo-editor/test/utils'
 
 // Legacy
 import legacyEnv from 'web.commonEnv';
@@ -105,6 +106,47 @@ QUnit.module("WebEditor.HtmlField", ({ beforeEach }) => {
         assert.equal(mediaDialog.props.resId, 2);
     });
 
+    QUnit.test("discard html field changes in form", async (assert) => {
+        serverData.models.partner.records = [{ id: 1, txt: "<p>first</p>" }];
+        let wysiwyg;
+        const wysiwygPromise = makeDeferred();
+        patchWithCleanup(HtmlField.prototype, {
+            async startWysiwyg() {
+                await this._super(...arguments);
+                wysiwyg = this.wysiwyg;
+                wysiwygPromise.resolve();
+            },
+        });
+        await makeView({
+            type: "form",
+            resId: 1,
+            resModel: "partner",
+            serverData,
+            arch: `
+                <form>
+                    <field name="txt" widget="html" options="{'style-inline' : true}"/>
+                </form>`,
+        });
+        await wysiwygPromise;
+        const editor = wysiwyg.odooEditor;
+        const editable = editor.editable;
+        editor.testMode = true;
+        assert.strictEqual(editable.innerHTML, `<p>first</p>`);
+        const paragraph = editable.querySelector("p");
+        await setSelection(paragraph, 0);
+        await insertText(editor, "a");
+        assert.strictEqual(editable.innerHTML, `<p>afirst</p>`);
+        // For blur event here to call _onWysiwygBlur function in html_field
+        await editable.dispatchEvent(new Event("blur", { bubbles: true, cancelable: true }));
+        // Wait for the updates to be saved , if we don't wait the update of the value will
+        // be done after the call for discardChanges since it uses some async functions.
+        await new Promise((r) => setTimeout(r, 100));
+        const discardButton = target.querySelector(".o_form_button_cancel");
+        assert.ok(discardButton);
+        await click(discardButton);
+        assert.strictEqual(editable.innerHTML, `<p>first</p>`);
+    });
+
     QUnit.module('Sandboxed Preview');
 
     QUnit.test("complex html is automatically in sandboxed preview mode", async (assert) => {