SnapshotUpgradeTest - Add support for pure-api4 entity

tests/e2e/SnapshotUpgradeTest.php

@@ -28,6 +28,7 @@
  *      - 'qf': An extension with some QuickForm pages/forms.
  *      - 'entity3': An extension with an entity supporting APIv3.
  *      - 'entity34': An extension with an entity supporting APIv3 and APIv4.
+ *      - 'entity4': An extension with an entity supporting APIv4.
  *      - 'kitchensink': An extension with a bunch of random things. (Varies based on the CIVIX_VERSION.)
  *      - 'svc': An extension with a service-object.
  *      - (NOTE: For a more detailed sketch of each scenario, see `tests/make-snapshots.sh`.)
@@ -143,6 +144,22 @@ public function checkSnapshot_entity34(): void {
     $this->assertTrue(in_array('FK to Contact', $descriptions4), "$entity.contact_id should have APIv4 description. Actual metadata response was: ");
   }
 
+  /**
+   * The "*-entity4.zip" snapshots include an entity ("MyEntityFour") with APIv4 support.
+   * This also appears in some kitchen-sink builds.
+   */
+  public function checkSnapshot_entity4(): void {
+    $this->runsIf($this->isScenario('entity4') || $this->isKitchenSinkWith('xml/schema/CRM/Civixsnapshot/MyEntityFour.xml'));
+
+    $entity = 'MyEntityFour';
+
+    $getFields4 = PH::runOK("cv api4 $entity.getFields --out=json");
+    $parsed4 = json_decode($getFields4->getOutput(), TRUE);
+    $descriptions4 = array_column($parsed4, 'description');
+    $this->assertTrue(in_array("Unique $entity ID", $descriptions4), "$entity.id should have APIv4 description. Actual metadata response was: ");
+    $this->assertTrue(in_array('FK to Contact', $descriptions4), "$entity.contact_id should have APIv4 description. Actual metadata response was: ");
+  }
+
   /**
    * The "*-qf.zip" snapshots include a traditional page+form (eg "civicrm/my-page").
    * This also appears in some kitchen-sink builds.