1 files changed, 97 insertions, 0 deletions

diff --git a/quantum/battery/tests/battery_tests.cpp b/quantum/battery/tests/battery_tests.cpp
new file mode 100644
index 0000000000..ee011be8a8
--- /dev/null
+++ b/quantum/battery/tests/battery_tests.cpp
@@ -0,0 +1,97 @@
+// Copyright 2025 QMK
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "gtest/gtest.h"
+#include "gmock/gmock.h"
+
+using testing::_;
+
+class BatteryDriverMock {
+   public:
+    virtual ~BatteryDriverMock() {}
+
+    // mock methods
+    MOCK_METHOD0(battery_driver_init, void(void));
+    MOCK_METHOD0(battery_driver_sample_percent, uint8_t(void));
+    MOCK_METHOD1(battery_percent_changed_kb, void(uint8_t));
+};
+
+class BatteryTest : public ::testing::Test {
+   public:
+    BatteryTest() {
+        _batteryDriverMock.reset(new ::testing::NiceMock<BatteryDriverMock>());
+    }
+    virtual ~BatteryTest() {
+        _batteryDriverMock.reset();
+    }
+
+    static std::unique_ptr<BatteryDriverMock> _batteryDriverMock;
+};
+
+std::unique_ptr<BatteryDriverMock> BatteryTest::_batteryDriverMock;
+
+extern "C" {
+#include "quantum/battery/battery.h"
+#include "timer.h"
+
+void advance_time(uint32_t ms);
+
+void battery_driver_init(void) {
+    if (BatteryTest::_batteryDriverMock) {
+        BatteryTest::_batteryDriverMock->battery_driver_init();
+    }
+}
+
+uint8_t battery_driver_sample_percent(void) {
+    if (BatteryTest::_batteryDriverMock) {
+        return BatteryTest::_batteryDriverMock->battery_driver_sample_percent();
+    }
+    return 255;
+}
+
+void battery_percent_changed_kb(uint8_t level) {
+    if (BatteryTest::_batteryDriverMock) {
+        BatteryTest::_batteryDriverMock->battery_percent_changed_kb(level);
+    }
+}
+}
+
+TEST_F(BatteryTest, TestInit) {
+    // init driver and initial sample
+    EXPECT_CALL(*_batteryDriverMock, battery_driver_init()).Times(1);
+    EXPECT_CALL(*_batteryDriverMock, battery_driver_sample_percent()).Times(1);
+
+    battery_init();
+}
+
+TEST_F(BatteryTest, TestSampleCached) {
+    // sample before timeout
+    EXPECT_CALL(*_batteryDriverMock, battery_driver_sample_percent()).Times(0);
+
+    advance_time(1);
+    battery_task();
+}
+
+TEST_F(BatteryTest, TestSampleNotCached) {
+    // sample after timeout
+    EXPECT_CALL(*_batteryDriverMock, battery_driver_sample_percent()).Times(1);
+
+    advance_time(60000);
+    battery_task();
+}
+
+TEST_F(BatteryTest, TestGet) {
+    // sample does not directly sample
+    EXPECT_CALL(*_batteryDriverMock, battery_driver_sample_percent()).Times(0);
+
+    battery_get_percent();
+}
+
+TEST_F(BatteryTest, TestChanged) {
+    // callbacks on value changed
+    EXPECT_CALL(*_batteryDriverMock, battery_percent_changed_kb(_)).Times(1);
+
+    battery_task();
+    advance_time(60000);
+    battery_task();
+}