Can not delete workspace if it has associated content

+++ b/core/modules/workspaces/tests/src/Functional/WorkspaceDeleteFromUiTest.php
@@ -0,0 +1,53 @@
+ * Tests access bypass permission controls on workspaces.
...
+   * Verifies that a user can edit anything in a workspace they own.

these comments look to be copy/paste

Other than that, this looks good to me

Nice find! I looked around and we only test deleting workspaces in a kernel test, that's why we missed this in #3062434: Track the workspace of a revision in a base field and convert the workspace_association entity type to a custom index.

1. +++ b/core/modules/workspaces/tests/src/Functional/WorkspaceDeleteFromUiTest.php
   @@ -0,0 +1,53 @@
   +   * Verifies that uid 1 can delete workspaces from the UI.
   

   It's not really relevant which user deletes the workspace, so we could change this to "Verifies that a workspace with existing content can be deleted."

2. +++ b/core/modules/workspaces/tests/src/Functional/WorkspaceDeleteFromUiTest.php
   @@ -0,0 +1,53 @@
   +  public function testDeleteWorkspaceFromUi() {
   

   Let's move this test method to the existing functional test for workspace's UI: \Drupal\Tests\workspaces\Functional\WorkspaceTest

   and rename it to testDeleteWorkspaceWithExistingContent

3. +++ b/core/modules/workspaces/tests/src/Functional/WorkspaceDeleteFromUiTest.php
   @@ -0,0 +1,53 @@
   +    $page = $this->getSession()->getPage();
   +    $page->findLink('Switch to May 4')->click();
   +    $page = $this->getSession()->getPage();
   +    $page->findButton('Confirm')->click();
   

   Let's use switchToWorkspace() instead.

4. +++ b/core/modules/workspaces/tests/src/Functional/WorkspaceDeleteFromUiTest.php
   @@ -0,0 +1,53 @@
   +    $page->hasContent("The workspace May 4 has been deleted.");
   

   We can use single quotes here :)

Thanks, looks great now!

Please ignore #17, the patch from #15 is the one that is RTBC.

Committed/pushed to 9.2.x and cherry-picked to 9.1.x, thanks!