Add simple unit tests for DataBuf

unitTests/test_types.cpp

@@ -23,4 +23,16 @@ TEST(ExivTime, doesNotGetTimeWithBadFormedString)
     ASSERT_EQ(1, exifTime("007:a5:24 aa:bb:cc", &tmInstance));
 }
 
+TEST(DataBuf, pointsToNullByDefault)
+{
+    DataBuf instance;
+    ASSERT_EQ(NULL, instance.pData_);
+    ASSERT_EQ(0,    instance.size_);
+}
+
+TEST(DataBuf, allocatesDataWithNonEmptyConstructor)
+{
+    DataBuf instance (5);
+    ASSERT_NE(static_cast<byte *>(NULL), instance.pData_); /// \todo use nullptr once we move to c++11
+    ASSERT_EQ(5,    instance.size_);
 }