Add new unit tests

tests/Makefile

@@ -0,0 +1,18 @@
+SRC_PATH=./src
+OUT_PATH=./bin
+TEST_SRC=$(wildcard ${SRC_PATH}/*_spec.cpp)
+TEST_BIN= $(TEST_SRC:${SRC_PATH}/%.cpp=${OUT_PATH}/%)
+VPATH=${SRC_PATH}
+SHIM_FILES=${SRC_PATH}/lib/*.cpp
+PSC_FILE=../PubSubClient/PubSubClient.cpp
+CC=g++
+CFLAGS=-I${SRC_PATH}/lib -I../PubSubClient
+
+all: $(TEST_BIN)
+
+${OUT_PATH}/%: ${SRC_PATH}/%.cpp ${PSC_FILE} ${SHIM_FILES}
+	mkdir -p ${OUT_PATH}
+	${CC} ${CFLAGS} $^ -o $@
+	
+clean:
+	@rm -rf ${OUT_PATH}