Unit testing arduino code with std::string

Advanced Solutions Unit Testing
1

hello guys,
I’m trying to unittest some class that has parametter std::string. I’m including <string> inside header file, thats working inside unit testing area.

#ifndef USB_RECEIVER_H
#define USB_RECEIVER_H
#include <string>


class USBreceiver
{
public:
    bool messageIsComplete();
    void addData(std::string data);
    std::string getData();
    
private:
};

#endif

For testing I’m usign googletest in native enviroment
platformio.ini

[env:uno]
platform = atmelavr
board = uno
framework = arduino
test_ignore = test_desktop

[env:native]
platform = native
test_framework = googletest
build_type = debug
debug_test = test_desktop
debug_init_break = tbreak loop
test_ignore = test_HW

But i cannot compile this code for uploading into arduino. Compiler does not know . I also cannot use the String class from arduino because while compiling in testing files there is not connection to Arduino.h

Can you help me? What library should I use that is compilable in both enviroments?
with thanks
rytir.ch

2

Use this GitHub - FabioBatSilva/ArduinoFake: Arduino mocking made easy – it is very limited, but I tested it covers the basics.

I’ve actually created 3 envs:

  1. native – for “pure” C++ code, that works everywhere and can be easily tested
  2. native_arduino – for code that can be mocked by ArduinoFake, and thus tested as well
  3. nodemcu (could be called just arduino) – for the specific code that cannot be tested. And by “cannot” I mean: would be hard to test or would have to be tested on the device anyway, so I’m not really that interested.

I’m trying to have as much as I can in the native section, and keep arduino–specific code small, simple and isolated.

Remember, u have to separate the code by having it in different “libraries” (folders in lib dir) and “front controllers” (apps in src), due to limitation of LDF.

3

well thank you but unfortunetly if i use ArduinoFake and its String, I cannot than use this code for different chip that is not arduino supported. Is there any way how to achive this?

4

You can always add another layer of abstraction :wink:

It makes code a bit more complicated, but I’d argue this is the use–case polymorphism was born for.

class String {
  virtual const char* toCString() = 0;
  // etc.
}

class ArduinoString: public String { /* Arduino's String implementation */ }

class StdString: public String { /* std::string impl */ }

class StringFactory {} // abstract factory pattern

// somewhere in the code
String theString = stringFactory.create("foo bar baz"); // can be ArduinoString or StdString

Yea, I know that look. I probably have a tendency to overengineer stuff xd And I’m an OOP fanboy. Two of the things, I started to notice, that are disliked in C++/mC world ;p

Or, you can just use C–strings everywhere (yep, sucks).

Or… are you sure std::string does not work in Arduino–env? I think it actually worked for me (although it is discouraged for sure). I will test that later.