fixed memory leak in string buffer

Firmata.cpp

@@ -181,6 +181,8 @@ void FirmataClass::processSysexMessage(void)
         j++;
       }
       (*currentStringCallback)(buffer);
+      free(buffer);
+      buffer = 0;
     }
     break;
   default:

examples/EchoString/EchoString.ino

@@ -28,7 +28,7 @@ void sysexCallback(byte command, byte argc, byte*argv)
 
 void setup()
 {
-    Firmata.setFirmwareVersion(0, 1);
+    Firmata.setFirmwareVersion(FIRMATA_MAJOR_VERSION, FIRMATA_MINOR_VERSION);
     Firmata.attach(STRING_DATA, stringCallback);
     Firmata.attach(START_SYSEX, sysexCallback);
     Firmata.begin(57600);

test/unit/firmata_test/firmata_test.ino

@@ -18,21 +18,6 @@ void loop()
   Test::run();
 }
 
-// Note: this test required adding a method (Firmata.unsetFirmwareVersion()) to 
-// Firmata.cpp solely for the purpose of running this test. The method has been 
-// removed from Firmata.cpp, but keeping the test here as a recored 
-// test(setFirmwareVersionDoesNotLeakMemory)
-// {
-//   Firmata.setFirmwareVersion(1, 0);
-//   int initialMemory = freeMemory();
-
-//   Firmata.setFirmwareVersion(1, 0);
-
-//   assertEquals(0, initialMemory - freeMemory());
-
-//   Firmata.unsetFirmwareVersion();
-// }
-
 test(beginPrintsVersion)
 {
   FakeStream stream;
@@ -61,6 +46,10 @@ void processMessage(const byte* message, size_t length)
   }
 }
 
+void stringCallback(char *myString)
+{
+}
+
 byte _digitalPort;
 int _digitalPortValue;
 void writeToDigitalPort(byte port, int value)
@@ -140,3 +129,28 @@ test(specifiedDigitalWritePort)
 
   assertEqual(1, _digitalPort);
 }
+
+test(stringDataDoesNotLeakMemory)
+{
+  Firmata.attach(STRING_DATA, stringCallback);
+
+  int initialMemory = freeMemory();
+
+  byte stringMsg[] = { START_SYSEX, STRING_DATA, 72, 0, 101, 0, 108, 0, 108, 0, 111, 0, END_SYSEX };
+
+  for (int i = 0; i < 4; i++) {
+    processMessage(stringMsg, 13);
+  }
+
+  assertEqual(0, initialMemory - freeMemory());
+}
+
+test(setFirmwareVersionDoesNotLeakMemory)
+{
+  Firmata.setFirmwareVersion(1, 0);
+  int initialMemory = freeMemory();
+
+  Firmata.setFirmwareVersion(1, 0);
+
+  assertEqual(0, initialMemory - freeMemory());
+}