Minimal Wire.h mock

Most functions are empty and unfinished, so you will not (yet) be able
to unit test I2C communication. But it will allow you to unit test code
that is using libraries that uses I2C under the hood (e.g. LCD, RTC, etc).

Author: hlovdal

cpp/arduino/Arduino.h

@@ -15,6 +15,7 @@ Where possible, variable names from the Arduino library are used to avoid confli
 #include "Stream.h"
 #include "HardwareSerial.h"
 #include "SPI.h"
+#include "Wire.h"
 
 typedef bool boolean;
 typedef uint8_t byte;

cpp/arduino/Godmode.cpp

@@ -1,6 +1,7 @@
 #include "Godmode.h"
 #include "HardwareSerial.h"
 #include "SPI.h"
+#include "Wire.h"
 
 GodmodeState godmode = GodmodeState();
 
@@ -101,3 +102,6 @@ inline std::ostream& operator << ( std::ostream& out, const PinHistory<T>& ph )
 
 // defined in SPI.h
 SPIClass SPI = SPIClass(&godmode.spi.dataIn, &godmode.spi.dataOut);
+
+// defined in Wire.h
+TwoWire Wire = TwoWire(&godmode.wire.dataIn, &godmode.wire.dataOut);

cpp/arduino/Godmode.h

@@ -52,6 +52,7 @@ class GodmodeState {
     struct PortDef serialPort[NUM_SERIAL_PORTS];
     struct InterruptDef interrupt[MOCK_PINS_COUNT]; // not sure how to get actual number
     struct PortDef spi;
+    struct PortDef wire;
 
     void resetPins() {
       for (int i = 0; i < MOCK_PINS_COUNT; ++i) {

cpp/arduino/Wire.h

@@ -0,0 +1,142 @@
+
+#pragma once
+
+#include <inttypes.h>
+#include "Stream.h"
+
+class TwoWire : public ObservableDataStream
+{
+public:
+  TwoWire(String *dataIn, String *dataOut) {
+    this->dataIn = dataIn;
+    this->dataOut = dataOut;
+  }
+
+  // https://www.arduino.cc/en/Reference/WireBegin
+  // Initiate the Wire library and join the I2C bus as a master or slave. This should normally be called only once.
+  void begin() {
+    isMaster = true;
+  }
+  void begin(int address) {
+    i2cAddress = address;
+    isMaster = false;
+  }
+  void begin(uint8_t address) {
+    begin((int)address);
+  }
+  void end() {
+    // TODO: implement
+  }
+
+  // https://www.arduino.cc/en/Reference/WireSetClock
+  // This function modifies the clock frequency for I2C communication. I2C slave devices have no minimum working
+  // clock frequency, however 100KHz is usually the baseline.
+  void setClock(uint32_t) {
+    // TODO: implement?
+  }
+
+  // https://www.arduino.cc/en/Reference/WireBeginTransmission
+  // Begin a transmission to the I2C slave device with the given address. Subsequently, queue bytes for
+  // transmission with the write() function and transmit them by calling endTransmission().
+  void beginTransmission(int address) {
+    // TODO: implement
+  }
+  void beginTransmission(uint8_t address) {
+    beginTransmission((int)address);
+  }
+
+  // https://www.arduino.cc/en/Reference/WireEndTransmission
+  // Ends a transmission to a slave device that was begun by beginTransmission() and transmits the bytes that were
+  // queued by write().
+  uint8_t endTransmission(uint8_t sendStop) {
+    // TODO: implement
+    return 0; // success
+  }
+  uint8_t endTransmission(void) {
+    return endTransmission((uint8_t)true);
+  }
+
+  // https://www.arduino.cc/en/Reference/WireRequestFrom
+  // Used by the master to request bytes from a slave device. The bytes may then be retrieved with the
+  // available() and read() functions.
+  uint8_t requestFrom(int address, int quantity, int stop) {
+    // TODO: implement
+    return 0; // number of bytes returned from the slave device
+  }
+  uint8_t requestFrom(int address, int quantity) {
+    int stop = true;
+    return requestFrom(address, quantity, stop);
+  }
+  uint8_t requestFrom(uint8_t address, uint8_t quantity) {
+    return requestFrom((int)address, (int)quantity);
+  }
+  uint8_t requestFrom(uint8_t address, uint8_t quantity, uint8_t stop) {
+    return requestFrom((int)address, (int)quantity, (int)stop);
+  }
+  uint8_t requestFrom(uint8_t, uint8_t, uint32_t, uint8_t, uint8_t) {
+    // TODO: implement
+    return 0;
+  }
+
+  // https://www.arduino.cc/en/Reference/WireWrite
+  // Writes data from a slave device in response to a request from a master, or queues bytes for transmission from a
+  // master to slave device (in-between calls to beginTransmission() and endTransmission()).
+  size_t write(uint8_t value) {
+    // TODO: implement
+    return 0; // number of bytes written
+  }
+  size_t write(const char *str) { return str == NULL ? 0 : write((const uint8_t *)str, String(str).length()); }
+  size_t write(const uint8_t *buffer, size_t size) {
+    size_t n;
+    for (n = 0; size && write(*buffer++) && ++n; --size);
+    return n;
+  }
+  size_t write(const char *buffer, size_t size) { return write((const uint8_t *)buffer, size); }
+  size_t write(unsigned long n) { return write((uint8_t)n); }
+  size_t write(long n) { return write((uint8_t)n); }
+  size_t write(unsigned int n) { return write((uint8_t)n); }
+  size_t write(int n) { return write((uint8_t)n); }
+
+  // https://www.arduino.cc/en/Reference/WireAvailable
+  // Returns the number of bytes available for retrieval with read(). This should be called on a master device after a
+  // call to requestFrom() or on a slave inside the onReceive() handler.
+  int available(void) {
+    // TODO: implement
+    return 0; // number of bytes available for reading
+  }
+
+  // https://www.arduino.cc/en/Reference/WireRead
+  // Reads a byte that was transmitted from a slave device to a master after a call to requestFrom() or was transmitted
+  // from a master to a slave. read() inherits from the Stream utility class.
+  int read(void) {
+    // TODO: implement
+    return '\0'; // The next byte received
+  }
+  int peek(void) {
+    // TODO: implement
+    return 0;
+  }
+  void flush(void) {
+    // TODO: implement
+  }
+
+  // https://www.arduino.cc/en/Reference/WireOnReceive
+  // Registers a function to be called when a slave device receives a transmission from a master.
+  void onReceive( void (*callback)(int) ) {
+    // TODO: implement
+  }
+
+  // https://www.arduino.cc/en/Reference/WireOnRequest
+  // Register a function to be called when a master requests data from this slave device.
+  void onRequest( void (*callback)(void) ) {
+    // TODO: implement
+  }
+
+private:
+  int i2cAddress;
+  bool isMaster = false;
+  String *dataIn;
+  String *dataOut;
+};
+
+extern TwoWire Wire;