diff --git a/src/main/drivers/gpio.h b/src/main/drivers/gpio.h
index 0110875832..1385a13dd8 100644
--- a/src/main/drivers/gpio.h
+++ b/src/main/drivers/gpio.h
@@ -17,7 +17,7 @@
 
 #pragma once
 
-#ifdef STM32F10X
+#if defined(STM32F10X) || defined(UNIT_TEST)
 typedef enum
 {
     Mode_AIN = 0x0,
diff --git a/src/main/drivers/serial_softserial.c b/src/main/drivers/serial_softserial.c
index 2490c83499..b81a6bbd19 100644
--- a/src/main/drivers/serial_softserial.c
+++ b/src/main/drivers/serial_softserial.c
@@ -45,6 +45,41 @@
 #define MAX_SOFTSERIAL_PORTS 1
 #endif
 
+typedef struct softSerial_s {
+    serialPort_t     port;
+
+    const timerHardware_t *rxTimerHardware;
+    volatile uint8_t rxBuffer[SOFTSERIAL_BUFFER_SIZE];
+
+    const timerHardware_t *txTimerHardware;
+    volatile uint8_t txBuffer[SOFTSERIAL_BUFFER_SIZE];
+
+    uint8_t          isSearchingForStartBit;
+    uint8_t          rxBitIndex;
+    uint8_t          rxLastLeadingEdgeAtBitIndex;
+    uint8_t          rxEdge;
+
+    uint8_t          isTransmittingData;
+    int8_t           bitsLeftToTransmit;
+
+    uint16_t         internalTxBuffer;  // includes start and stop bits
+    uint16_t         internalRxBuffer;  // includes start and stop bits
+
+    uint16_t         transmissionErrors;
+    uint16_t         receiveErrors;
+
+    uint8_t          softSerialPortIndex;
+
+    timerCCHandlerRec_t timerCb;
+    timerCCHandlerRec_t edgeCb;
+} softSerial_t;
+
+extern timerHardware_t* serialTimerHardware;
+extern softSerial_t softSerialPorts[];
+
+extern const struct serialPortVTable softSerialVTable[];
+
+
 softSerial_t softSerialPorts[MAX_SOFTSERIAL_PORTS];
 
 void onSerialTimer(timerCCHandlerRec_t *cbRec, captureCompare_t capture);
diff --git a/src/main/drivers/serial_softserial.h b/src/main/drivers/serial_softserial.h
index 17df635df3..cbf933246d 100644
--- a/src/main/drivers/serial_softserial.h
+++ b/src/main/drivers/serial_softserial.h
@@ -24,40 +24,6 @@ typedef enum {
     SOFTSERIAL2
 } softSerialPortIndex_e;
 
-typedef struct softSerial_s {
-    serialPort_t     port;
-
-    const timerHardware_t *rxTimerHardware;
-    volatile uint8_t rxBuffer[SOFTSERIAL_BUFFER_SIZE];
-
-    const timerHardware_t *txTimerHardware;
-    volatile uint8_t txBuffer[SOFTSERIAL_BUFFER_SIZE];
-
-    uint8_t          isSearchingForStartBit;
-    uint8_t          rxBitIndex;
-    uint8_t          rxLastLeadingEdgeAtBitIndex;
-    uint8_t          rxEdge;
-
-    uint8_t          isTransmittingData;
-    int8_t           bitsLeftToTransmit;
-
-    uint16_t         internalTxBuffer;  // includes start and stop bits
-    uint16_t         internalRxBuffer;  // includes start and stop bits
-
-    uint16_t         transmissionErrors;
-    uint16_t         receiveErrors;
-
-    uint8_t          softSerialPortIndex;
-
-    timerCCHandlerRec_t timerCb;
-    timerCCHandlerRec_t edgeCb;
-} softSerial_t;
-
-extern timerHardware_t* serialTimerHardware;
-extern softSerial_t softSerialPorts[];
-
-extern const struct serialPortVTable softSerialVTable[];
-
 serialPort_t *openSoftSerial(softSerialPortIndex_e portIndex, serialReceiveCallbackPtr callback, uint32_t baud, portOptions_t options);
 
 // serialPort API
diff --git a/src/main/io/serial.c b/src/main/io/serial.c
index 377d326229..be9940eb51 100644
--- a/src/main/io/serial.c
+++ b/src/main/io/serial.c
@@ -27,12 +27,18 @@
 #include "common/utils.h"
 
 #include "drivers/system.h"
-#include "drivers/gpio.h"
-#include "drivers/timer.h"
 #include "drivers/serial.h"
+#if defined(USE_SOFTSERIAL1) || defined(USE_SOFTSERIAL2)
 #include "drivers/serial_softserial.h"
+#endif
+
+#if defined(USE_USART1) || defined(USE_USART2) || defined(USE_USART3)
 #include "drivers/serial_uart.h"
+#endif
+
+#if defined(USE_VCP)
 #include "drivers/serial_usb_vcp.h"
+#endif
 
 #include "io/serial.h"
 #include "serial_cli.h"
diff --git a/src/main/io/serial.h b/src/main/io/serial.h
index e02bf83182..53a4d7b56e 100644
--- a/src/main/io/serial.h
+++ b/src/main/io/serial.h
@@ -60,7 +60,7 @@ typedef enum {
     SERIAL_PORT_IDENTIFIER_MAX = SERIAL_PORT_SOFTSERIAL2
 } serialPortIdentifier_e;
 
-serialPortIdentifier_e serialPortIdentifiers[SERIAL_PORT_COUNT];
+extern serialPortIdentifier_e serialPortIdentifiers[SERIAL_PORT_COUNT];
 
 //
 // runtime
diff --git a/src/main/io/serial_cli.c b/src/main/io/serial_cli.c
index 4cb67ce8e7..5d55cb6f35 100644
--- a/src/main/io/serial_cli.c
+++ b/src/main/io/serial_cli.c
@@ -1611,7 +1611,7 @@ static void cliVersion(char *cmdline)
     );
 }
 
-void cliProcess()
+void cliProcess(void)
 {
     if (!cliPort) {
         return;
diff --git a/src/test/Makefile b/src/test/Makefile
index f60ee6cc82..fb5f8beb6a 100644
--- a/src/test/Makefile
+++ b/src/test/Makefile
@@ -55,6 +55,7 @@ TESTS = \
 	ledstrip_unittest \
 	ws2811_unittest \
 	encoding_unittest \
+	io_serial_unittest \
 	lowpass_unittest
 
 # All Google Test headers.  Usually you shouldn't change this
@@ -389,6 +390,28 @@ flight_mixer_unittest : \
 
 	$(CXX) $(CXX_FLAGS) -lpthread $^ -o $(OBJECT_DIR)/$@
 
+$(OBJECT_DIR)/io/serial.o : \
+	$(USER_DIR)/io/serial.c \
+	$(USER_DIR)/io/serial.h \
+	$(GTEST_HEADERS)
+
+	@mkdir -p $(dir $@)
+	$(CC) $(C_FLAGS) $(TEST_CFLAGS) -c $(USER_DIR)/io/serial.c -o $@
+
+$(OBJECT_DIR)/io_serial_unittest.o : \
+	$(TEST_DIR)/io_serial_unittest.cc \
+	$(USER_DIR)/io/serial.h \
+	$(GTEST_HEADERS)
+
+	@mkdir -p $(dir $@)
+	$(CXX) $(CXX_FLAGS) $(TEST_CFLAGS) -c $(TEST_DIR)/io_serial_unittest.cc -o $@
+
+io_serial_unittest : \
+	$(OBJECT_DIR)/io/serial.o \
+	$(OBJECT_DIR)/io_serial_unittest.o \
+	$(OBJECT_DIR)/gtest_main.a
+
+	$(CXX) $(CXX_FLAGS) -lpthread $^ -o $(OBJECT_DIR)/$@
 
 test: $(TESTS)
 	set -e && for test in $(TESTS) ; do \
diff --git a/src/test/unit/altitude_hold_unittest.cc b/src/test/unit/altitude_hold_unittest.cc
index 3b9ba887cd..6a1008bbf1 100644
--- a/src/test/unit/altitude_hold_unittest.cc
+++ b/src/test/unit/altitude_hold_unittest.cc
@@ -71,17 +71,17 @@ TEST(AltitudeHoldTest, IsThrustFacingDownwards)
     // given
 
     inclinationExpectation_t inclinationExpectations[] = {
-            { { 0, 0 }, DOWNWARDS_THRUST },
-            { { 799, 799 }, DOWNWARDS_THRUST },
-            { { 800, 799 }, UPWARDS_THRUST },
-            { { 799, 800 }, UPWARDS_THRUST },
-            { { 800, 800 }, UPWARDS_THRUST },
-            { { 801, 801 }, UPWARDS_THRUST },
-            { { -799, -799 }, DOWNWARDS_THRUST },
-            { { -800, -799 }, UPWARDS_THRUST },
-            { { -799, -800 }, UPWARDS_THRUST },
-            { { -800, -800 }, UPWARDS_THRUST },
-            { { -801, -801 }, UPWARDS_THRUST }
+            { {{    0,    0 }}, DOWNWARDS_THRUST },
+            { {{  799,  799 }}, DOWNWARDS_THRUST },
+            { {{  800,  799 }}, UPWARDS_THRUST },
+            { {{  799,  800 }}, UPWARDS_THRUST },
+            { {{  800,  800 }}, UPWARDS_THRUST },
+            { {{  801,  801 }}, UPWARDS_THRUST },
+            { {{ -799, -799 }}, DOWNWARDS_THRUST },
+            { {{ -800, -799 }}, UPWARDS_THRUST },
+            { {{ -799, -800 }}, UPWARDS_THRUST },
+            { {{ -800, -800 }}, UPWARDS_THRUST },
+            { {{ -801, -801 }}, UPWARDS_THRUST }
     };
     uint8_t testIterationCount = sizeof(inclinationExpectations) / sizeof(inclinationExpectation_t);
 
@@ -105,18 +105,18 @@ typedef struct inclinationAngleExpectations_s {
 TEST(AltitudeHoldTest, TestCalculateTiltAngle)
 {
     inclinationAngleExpectations_t inclinationAngleExpectations[] = {
-        { {0, 0}, 0},
-        { {1, 0}, 1},
-        { {0, 1}, 1},
-        { {0, -1}, 1},
-        { {-1, 0}, 1},
-        { {-1, -2}, 2},
-        { {-2, -1}, 2},
-        { {1, 2}, 2},
-        { {2, 1}, 2}
+        { {{ 0,  0}}, 0},
+        { {{ 1,  0}}, 1},
+        { {{ 0,  1}}, 1},
+        { {{ 0, -1}}, 1},
+        { {{-1,  0}}, 1},
+        { {{-1, -2}}, 2},
+        { {{-2, -1}}, 2},
+        { {{ 1,  2}}, 2},
+        { {{ 2,  1}}, 2}
     };
 
-    rollAndPitchInclination_t inclination = {0, 0};
+    rollAndPitchInclination_t inclination = {{0, 0}};
     uint16_t tilt_angle = calculateTiltAngle(&inclination);
     EXPECT_EQ(tilt_angle, 0);
 
diff --git a/src/test/unit/io_serial_unittest.cc b/src/test/unit/io_serial_unittest.cc
new file mode 100644
index 0000000000..e063c250e9
--- /dev/null
+++ b/src/test/unit/io_serial_unittest.cc
@@ -0,0 +1,73 @@
+/*
+ * This file is part of Cleanflight.
+ *
+ * Cleanflight is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Cleanflight is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include <limits.h>
+
+extern "C" {
+    #include "platform.h"
+
+    #include "drivers/serial.h"
+    #include "io/serial.h"
+
+    void serialInit(serialConfig_t *initialSerialConfig);
+
+}
+
+#include "unittest_macros.h"
+#include "gtest/gtest.h"
+
+//uint32_t testFeatureMask = 0;
+uint8_t cliMode = 0;
+
+TEST(IoSerialTest, TestFindPortConfig)
+{
+    // given
+    serialConfig_t serialConfig;
+    memset(&serialConfig, 0, sizeof(serialConfig));
+
+    // when
+    serialInit(&serialConfig);
+
+    // and
+    serialPortConfig_t *portConfig = findSerialPortConfig(FUNCTION_MSP);
+
+    // then
+    EXPECT_EQ(NULL, portConfig);
+}
+
+
+// STUBS
+
+extern "C" {
+//
+//bool feature(uint32_t mask) {
+//    return (mask & testFeatureMask);
+//}s
+
+void delay(uint32_t) {}
+void cliEnter(serialPort_t *) {}
+void cliProcess(void) {}
+bool isSerialTransmitBufferEmpty(serialPort_t *) {
+    return true;
+}
+void mspProcess(void) {}
+void systemResetToBootloader(void) {}
+
+}
diff --git a/src/test/unit/ledstrip_unittest.cc b/src/test/unit/ledstrip_unittest.cc
index b650efebcd..739982a6ca 100644
--- a/src/test/unit/ledstrip_unittest.cc
+++ b/src/test/unit/ledstrip_unittest.cc
@@ -418,6 +418,6 @@ int scaleRange(int x, int srcMin, int srcMax, int destMin, int destMax) {
     return 0;
 }
 
-bool failsafeHasTimerElapsed(void) { }
+bool failsafeHasTimerElapsed(void) { return false; }
 
 }