fix: make auto-width and text-align usable in custom slot

packages/grid/src/vaadin-grid-column-mixin.js

@@ -487,7 +487,7 @@ export const ColumnBaseMixin = (superClass) =>
 
     /** @private */
     _textAlignChanged(textAlign) {
-      if (textAlign === undefined) {
+      if (textAlign === undefined || this._grid === undefined) {
         return;
       }
       if (['start', 'end', 'center'].indexOf(textAlign) === -1) {

packages/grid/src/vaadin-grid-mixin.js

@@ -339,7 +339,10 @@ export const GridMixin = (superClass) =>
         return 0;
       }
 
-      const columnWidth = Math.max(this.__getIntrinsicWidth(col), this.__getDistributedWidth(col.parentElement, col));
+      const columnWidth = Math.max(
+        this.__getIntrinsicWidth(col),
+        this.__getDistributedWidth((col.assignedSlot || col).parentElement, col),
+      );
 
       // We're processing a regular grid-column and not a grid-column-group
       if (!innerColumn) {

packages/grid/test/grid-wrapper-polymer.test.js

@@ -0,0 +1,2 @@
+import '../all-imports.js';
+import './grid-wrapper.common.js';

packages/grid/test/grid-wrapper.common.js

@@ -0,0 +1,59 @@
+import { expect } from '@esm-bundle/chai';
+import { fixtureSync, nextFrame } from '@vaadin/testing-helpers';
+import { flushGrid, getBodyCellContent } from './helpers';
+
+class GridWrapper extends HTMLElement {
+  constructor() {
+    super();
+    this.attachShadow({ mode: 'open' }).innerHTML = `
+      <vaadin-grid id="grid">
+        <vaadin-grid-column-group>
+          <slot name="group"></slot>
+        </vaadin-grid-column-group>
+        <slot></slot>
+      </vaadin-grid>
+    `;
+  }
+}
+
+customElements.define('grid-wrapper', GridWrapper);
+
+async function initGrid(wrapper) {
+  const grid = wrapper.shadowRoot.querySelector('vaadin-grid');
+  grid.items = Array.from({ length: 10 }).map((_, i) => ({ name: `Person ${i}` }));
+  flushGrid(grid);
+  await nextFrame();
+  return grid;
+}
+
+describe('columns slotted in custom element', () => {
+  it('should render column correctly with auto-width defined', async () => {
+    const wrapper = fixtureSync(
+      '<grid-wrapper><vaadin-grid-column path="name" auto-width></vaadin-grid-column></grid-wrapper>',
+    );
+    const grid = await initGrid(wrapper);
+
+    expect(getBodyCellContent(grid, 0, 0).textContent).to.equal('Person 0');
+  });
+
+  it('should render column correctly with auto-width inside a column-group', async () => {
+    const wrapper = fixtureSync(
+      '<grid-wrapper><vaadin-grid-column slot="group" path="name" auto-width></vaadin-grid-column></grid-wrapper>',
+    );
+    const grid = await initGrid(wrapper);
+
+    expect(getBodyCellContent(grid, 0, 0).textContent).to.equal('Person 0');
+  });
+
+  it('should render column correctly when text-align is defined', async () => {
+    const wrapper = fixtureSync(
+      '<grid-wrapper-delayed><vaadin-grid-column path="name" text-align="end"></vaadin-grid-column></grid-wrapper-delayed>',
+    );
+    // Delaying the definition of the custom-element so internal <vaadin-grid> is not yet defined
+    customElements.define('grid-wrapper-delayed', class extends GridWrapper {});
+
+    const grid = await initGrid(wrapper);
+
+    expect(getBodyCellContent(grid, 0, 0).textContent).to.equal('Person 0');
+  });
+});