tests: Fix as null descriptor with templates

Author: ziga-lunarg

tests/unit/descriptors_positive.cpp

@@ -1771,4 +1771,43 @@ TEST_F(PositiveDescriptors, NullDescriptorSetGPL) {
     vk::CmdBindDescriptorSets(m_command_buffer, VK_PIPELINE_BIND_POINT_GRAPHICS, pipeline_layout_null, 0u, 2u,
                               descriptor_set_handles, 0u, nullptr);
     m_command_buffer.End();
-}
+}
+
+TEST_F(PositiveDescriptors, AccelerationStructureTemplateNullDescriptor) {
+    SetTargetApiVersion(VK_API_VERSION_1_1);
+    AddRequiredExtensions(VK_KHR_ACCELERATION_STRUCTURE_EXTENSION_NAME);
+    AddRequiredExtensions(VK_KHR_BUFFER_DEVICE_ADDRESS_EXTENSION_NAME);
+    AddRequiredExtensions(VK_EXT_ROBUSTNESS_2_EXTENSION_NAME);
+    AddRequiredFeature(vkt::Feature::accelerationStructure);
+    AddRequiredFeature(vkt::Feature::bufferDeviceAddress);
+    AddRequiredFeature(vkt::Feature::nullDescriptor);
+    RETURN_IF_SKIP(Init());
+
+    OneOffDescriptorSet descriptor_set(m_device,
+                                       {
+                                           {0, VK_DESCRIPTOR_TYPE_ACCELERATION_STRUCTURE_KHR, 1, VK_SHADER_STAGE_ALL, nullptr},
+                                       });
+
+    struct SimpleTemplateData {
+        VkAccelerationStructureKHR as;
+    };
+
+    VkDescriptorUpdateTemplateEntry update_template_entry = {};
+    update_template_entry.dstBinding = 0;
+    update_template_entry.dstArrayElement = 0;
+    update_template_entry.descriptorCount = 1;
+    update_template_entry.descriptorType = VK_DESCRIPTOR_TYPE_ACCELERATION_STRUCTURE_KHR;
+    update_template_entry.offset = 0;
+    update_template_entry.stride = sizeof(SimpleTemplateData);
+
+    VkDescriptorUpdateTemplateCreateInfo update_template_ci = vku::InitStructHelper();
+    update_template_ci.descriptorUpdateEntryCount = 1;
+    update_template_ci.pDescriptorUpdateEntries = &update_template_entry;
+    update_template_ci.templateType = VK_DESCRIPTOR_UPDATE_TEMPLATE_TYPE_DESCRIPTOR_SET;
+    update_template_ci.descriptorSetLayout = descriptor_set.layout_;
+    vkt::DescriptorUpdateTemplate update_template(*m_device, update_template_ci);
+
+    SimpleTemplateData update_template_data;
+    update_template_data.as = VK_NULL_HANDLE;
+    vk::UpdateDescriptorSetWithTemplate(device(), descriptor_set.set_, update_template, &update_template_data);
+}