[ble_device_base] Replace raw-advertisement std::function with a lightweight callback slot (#17902)

tests/components/ble_device_base/test_raw_callback.cpp

@@ -0,0 +1,101 @@
+#include <gtest/gtest.h>
+
+#include <cstdint>
+
+#include "esphome/components/ble_device_base/ble_hub.h"
+
+namespace esphome::ble_device_base::testing {
+
+// Exercises the hub contract around RawAdvertisementCallback, not just the
+// struct: a hub stores one slot via set_raw_advertisement_callback(), fires it
+// only when set ("no subscriber" is the default-constructed slot), and a new
+// registration replaces the old ("one consumer at a time").
+//
+// The in-tree emit site (BK72xxBLETracker::on_scan_report) compiles against
+// the Beken SDK and cannot run host-side, so the guard-and-fire semantics are
+// pinned here through a minimal host BLEHub implementation instead.
+namespace {
+
+class FakeHub : public BLEHub {
+ public:
+  void register_listener(ESPBTDeviceListener *listener) override {}
+  void set_raw_advertisement_callback(RawAdvertisementCallback callback) override { this->callback_ = callback; }
+  HubCapabilities get_capabilities() const override { return {false, false, false}; }
+  void get_adapter_mac(uint8_t out[6]) override {}
+  bool scan_running() override { return false; }
+  bool scan_active() override { return false; }
+
+  /// The emit path every tracker implements: fire only when a subscriber is set.
+  void emit(const RawAdvertisement &adv) {
+    if (this->callback_.is_set())
+      this->callback_.invoke(adv);
+  }
+
+ protected:
+  RawAdvertisementCallback callback_;  // default-constructed: no subscriber
+};
+
+struct CapturingSubscriber {
+  RawAdvertisement last{};
+  int calls{0};
+
+  static void trampoline(void *self, const RawAdvertisement &adv) {
+    auto *sub = static_cast<CapturingSubscriber *>(self);
+    sub->last = adv;
+    sub->calls++;
+  }
+};
+
+// Device AA:BB:CC:DD:EE:FF — controller order delivers FF first.
+const uint8_t MAC_LSB_FIRST[6] = {0xff, 0xee, 0xdd, 0xcc, 0xbb, 0xaa};
+const uint8_t ADV_DATA[4] = {0x02, 0x01, 0x06, 0x00};
+
+RawAdvertisement make_test_adv() {
+  return RawAdvertisement{
+      .mac = MAC_LSB_FIRST, .data = ADV_DATA, .data_len = sizeof(ADV_DATA), .rssi = -63, .addr_type = 1};
+}
+
+}  // namespace
+
+TEST(RawAdvertisementCallback, DefaultConstructedSlotIsNotSet) {
+  const RawAdvertisementCallback callback{};
+  EXPECT_FALSE(callback.is_set());
+}
+
+TEST(RawAdvertisementCallback, SubscriberSeesFieldsUnchanged) {
+  FakeHub hub;
+  CapturingSubscriber subscriber;
+  hub.set_raw_advertisement_callback({&subscriber, CapturingSubscriber::trampoline});
+
+  hub.emit(make_test_adv());
+
+  ASSERT_EQ(subscriber.calls, 1);
+  EXPECT_EQ(subscriber.last.mac, MAC_LSB_FIRST);
+  EXPECT_EQ(subscriber.last.data, ADV_DATA);
+  EXPECT_EQ(subscriber.last.data_len, sizeof(ADV_DATA));
+  EXPECT_EQ(subscriber.last.rssi, -63);
+  EXPECT_EQ(subscriber.last.addr_type, 1);
+}
+
+TEST(RawAdvertisementCallback, NoSubscriberDoesNotFire) {
+  FakeHub hub;
+  // No set_raw_advertisement_callback(): emitting must be a guarded no-op,
+  // not a jump through a garbage pointer.
+  hub.emit(make_test_adv());
+}
+
+TEST(RawAdvertisementCallback, NewSubscriberReplacesOld) {
+  FakeHub hub;
+  CapturingSubscriber first;
+  CapturingSubscriber second;
+  hub.set_raw_advertisement_callback({&first, CapturingSubscriber::trampoline});
+  hub.set_raw_advertisement_callback({&second, CapturingSubscriber::trampoline});
+
+  hub.emit(make_test_adv());
+
+  EXPECT_EQ(first.calls, 0);  // one consumer at a time
+  ASSERT_EQ(second.calls, 1);
+  EXPECT_EQ(second.last.rssi, -63);
+}
+
+}  // namespace esphome::ble_device_base::testing