[mk2pvrouter] Add binary_sensor platform (#19719)

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/components/mk2pvrouter/binary_sensor/mk2pvrouter_binary_sensor_test.cpp

@@ -0,0 +1,21 @@
+#include <gtest/gtest.h>
+
+#include "esphome/components/mk2pvrouter/binary_sensor/mk2pvrouter_binary_sensor.h"
+
+namespace esphome::mk2pvrouter::testing {
+
+TEST(Mk2PVRouterBinarySensorTest, ZeroPublishesOff) {
+  Mk2PVRouterBinarySensor sensor("R1");
+  sensor.publish_val("0");
+  ASSERT_TRUE(sensor.has_state());
+  EXPECT_FALSE(sensor.state);
+}
+
+TEST(Mk2PVRouterBinarySensorTest, OnePublishesOn) {
+  Mk2PVRouterBinarySensor sensor("R1");
+  sensor.publish_val("1");
+  ASSERT_TRUE(sensor.has_state());
+  EXPECT_TRUE(sensor.state);
+}
+
+}  // namespace esphome::mk2pvrouter::testing

tests/components/mk2pvrouter/common.yaml

@@ -59,3 +59,10 @@ sensor:
     name: Relay 10 State
     tag: R10
     mk2pvrouter_id: test_mk2pvrouter
+
+binary_sensor:
+  # Test relay as binary sensor
+  - platform: mk2pvrouter
+    name: Relay 2 Binary
+    tag: R2
+    mk2pvrouter_id: test_mk2pvrouter