[FIX] clipboard: paste as value with empty format string

Our paste as value keeps the format from the origin cell, removing
only the formula. But if the origin cell had an empty format string,
it would copy this empty string instead of the evaluated cell format.

Note: we get empty string format as result of, for example, auto-fill
an `=TODAY()` formula. It can be argued that we should have `undefined`
core format rather than an empty string, but every other place in the
codebase handles all falsy format values the same way. The clipboard
was the only place where we would make the distinction between `""`
and `undefined` with `??`.

closes #7291

Task: 5156459
Signed-off-by: Rémi Rahir (rar) <rar@odoo.com>

Author: hokolomopo

src/clipboard_handlers/cell_clipboard.ts

@@ -237,7 +237,7 @@ export class CellClipboardHandler extends AbstractCellClipboardHandler<
   ) {
     const { sheetId, col, row } = target;
     const targetCell = this.getters.getEvaluatedCell(target);
-    const originFormat = origin?.format ?? origin.evaluatedCell.format;
+    const originFormat = origin?.format || origin.evaluatedCell.format;
 
     if (clipboardOption?.pasteOption === "asValue") {
       this.dispatch("UPDATE_CELL", {

tests/clipboard/clipboard_plugin.test.ts

@@ -1283,6 +1283,22 @@ describe("clipboard", () => {
     expect(getCellContent(model, "C3")).toBe("45.10%");
   });
 
+  test("paste as value works with both no core format and empty string core format", () => {
+    const model = new Model();
+    setCellContent(model, "D4", "=DATE(2024,6,5)");
+
+    copy(model, "D4");
+    paste(model, "E4", "asValue");
+    expect(getCell(model, "E4")).toMatchObject({ content: "45448", format: "m/d/yyyy" });
+
+    setFormat(model, "D4", ""); // An empty string format is equivalent to no format
+    expect(getCellContent(model, "D4")).toBe("6/5/2024");
+
+    copy(model, "D4");
+    paste(model, "E5", "asValue");
+    expect(getCell(model, "E5")).toMatchObject({ content: "45448", format: "m/d/yyyy" });
+  });
+
   test("can copy a formula and paste as value", () => {
     const model = new Model();
     setCellContent(model, "A1", "=SUM(1+2)");