[FIX] web: codeEditor: initial value is not up to be undone

Open the code editor (wrapper around aceEditor) with an initial value -- in Odoo, that is any instance of the code editor.
Press Ctrl+Z.

Before this commit, the value disappears -- is undone -- even though no real change happened.
This was because we used editor.setValue, instead of editor.session.setValue. The latter resetting the undo history.

This behavior is "documented" [here: Common Operations](https://ace.c9.io/#nav=howto) with:
```js
//Set and get content:

editor.setValue("the new text here");
editor.setValue("text2", -1); // set value and move cursor to the start of the text
editor.session.setValue("the new text here"); // set value and reset undo history
editor.getValue(); // or session.getValue
```

After this commit, the initial value is not undoable.

opw-3793546

closes odoo/odoo#158548

X-original-commit: b33086599383a4c0ab43126598a63e8721f682fc
Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>

addons/web/static/src/core/code_editor/code_editor.js

@@ -89,7 +89,7 @@ export class CodeEditor extends Component {
                 if (!sessions[this.props.sessionId]) {
                     sessions[this.props.sessionId] = session;
                 }
-                aceEditor.setValue(this.props.value);
+                session.setValue(this.props.value);
                 session.on("change", () => {
                     if (this.props.onChange && !ignoredAceChange) {
                         this.props.onChange(this.aceEditor.getValue());

addons/web/static/tests/core/code_editor_tests.js

@@ -8,6 +8,7 @@ import {
     mount,
     nextTick,
     editInput,
+    triggerEvents,
 } from "@web/../tests/helpers/utils";
 
 import { Component, markup, useState, xml } from "@odoo/owl";
@@ -184,7 +185,8 @@ QUnit.module("Web Components", (hooks) => {
         const codeEditor = await mount(Parent, target, { env });
         await nextTick();
         assert.equal(getDomValue(), textA, "Default value correctly set");
-
+        const aceEditor = window.ace.edit(target.querySelector(".ace_editor"));
+        aceEditor.selectAll();
         await edit(textB);
         assert.equal(
             getDomValue(),
@@ -261,4 +263,38 @@ QUnit.module("Web Components", (hooks) => {
         await nextTick();
         assert.verifySteps(["ace/theme/monokai"], "Monokai theme should be loaded");
     });
+
+    QUnit.test("initial value cannot be undone", async (assert) => {
+        class Parent extends Component {
+            static components = { CodeEditor };
+            static template = xml`<CodeEditor mode="'xml'" value="'some value'" />`;
+        }
+        await mount(Parent, target, { env });
+        await nextTick();
+        assert.containsOnce(target, ".ace_editor", "Code editor is rendered");
+        assert.strictEqual(
+            target.querySelector(".ace_editor .ace_content").textContent,
+            "some value"
+        );
+        const editor = window.ace.edit(target.querySelector(".ace_editor"));
+        const undo = editor.session.$undoManager.undo.bind(editor.session.$undoManager);
+        editor.session.$undoManager.undo = (...args) => {
+            assert.step("ace undo");
+            return undo(...args);
+        };
+        await triggerEvents(target, ".ace_editor textarea.ace_text-input", [
+            ["keydown", { key: "Control", keyCode: 17, which: 17 }],
+            ["keypress", { key: "Control", ctrlKey: true, keyCode: 17, which: 17 }],
+            ["keydown", { key: "z", ctrlKey: true, keyCode: 90, which: 90 }],
+            ["keypress", { key: "z", ctrlKey: true, keyCode: 90, which: 90 }],
+            ["keyup", { key: "z", ctrlKey: true, keyCode: 90, which: 90 }],
+            ["keyup", { key: "Control", keyCode: 17, which: 17 }],
+        ]);
+        await nextTick();
+        assert.strictEqual(
+            target.querySelector(".ace_editor .ace_content").textContent,
+            "some value"
+        );
+        assert.verifySteps(["ace undo"]);
+    });
 });