kapi/device: allow removing devices from busses

1 files changed, 61 insertions, 0 deletions

diff --git a/kernel/kapi/devices/bus.tests.cpp b/kernel/kapi/devices/bus.tests.cpp
index 9f95513b..0a33df1a 100644
--- a/kernel/kapi/devices/bus.tests.cpp
+++ b/kernel/kapi/devices/bus.tests.cpp
@@ -92,3 +92,64 @@ SCENARIO("A bus shares ownership of its children, holding a weak link to its par
     }
   }
 }
+
+SCENARIO("Removing a child from a bus tears down the while subtree", "[devices][bus]")
+{
+  GIVEN("A bus with a child bus")
+  {
+    auto root = kstd::make_shared<test_bus>("bus_removal_root");
+    auto middle = kstd::make_shared<test_bus>("bus_removal_middle");
+    auto leaf_destroyed = false;
+    auto leaf = kstd::make_shared<flagging_device>("bus_removal_leaf", leaf_destroyed);
+
+    root->add_child(middle);
+    middle->add_child(leaf);
+
+    REQUIRE(root->children().size() == 1);
+    REQUIRE(middle->children().size() == 1);
+
+    WHEN("the middle bus is removed from the root")
+    {
+      REQUIRE(root->remove_child(*middle));
+
+      THEN("the middle bus's own subtree was torn down")
+      {
+        REQUIRE(middle->children().empty());
+      }
+
+      THEN("the leaf is marked as removed but not destroyed")
+      {
+        REQUIRE(leaf->state() == kapi::devices::state::removed);
+        REQUIRE(leaf->parent() == nullptr);
+        REQUIRE_FALSE(leaf_destroyed);
+      }
+
+      AND_WHEN("dropping the outside leaf reference")
+      {
+        leaf.reset();
+
+        THEN("the leaf is destroyed")
+        {
+          REQUIRE(leaf_destroyed);
+        }
+      }
+
+      THEN("the root no longer considers the middle its child")
+      {
+        REQUIRE(root->children().empty());
+        REQUIRE(middle->state() == kapi::devices::state::removed);
+      }
+    }
+  }
+
+  GIVEN("A bus and a device that was never actually attached to it")
+  {
+    auto bus = kstd::make_shared<test_bus>("bus_removal_unrelated_bus");
+    auto unrelated = kstd::make_shared<test_device>("bus_removal_unrelated_device");
+
+    THEN("removing the child fails")
+    {
+      REQUIRE_FALSE(bus->remove_child(*unrelated));
+    }
+  }
+}