An Arduino test framework

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Testing is very undervalued in the Arduino community. Perhaps because without simulators, testing inevitably comes up short. I’ll conceded that it’s difficult to test the hardware with software, but I maintain that testing the algorithms present in well structured Arduino code is possible and beneficial. This is a sample of testing code which I used at power on in the puzzle box I used to propose.

// Minimal testing framework
#define b(v)   // Serial.println( v ? "true" : "false" );
#define p(a)   // Serial.print(a);
#define q(a,b) // Serial.print(a,b);

boolean tests_pass = true;

void assert(bool test){
  if (test) {
    p('.');
  } else {
    tests_pass = false;
    p('#');
  }
}

bool test_tests(){
  if ( ! tests_pass ) return false;
  assert(false);
  if ( tests_pass ) return false;
  tests_pass = true;

  return tests_pass;
}

// run the test method, and when things fail, put the Arduino into a lock and blink the LED
void test_lock(){
  p("\n\nSelf Test:");
  bool result = test();

  if ( result ) {
    gps.reset();

    p(": Pass\n");
    digitalWrite(13, HIGH);
    delay(500);
    digitalWrite(13, LOW);
    delay(50);
    digitalWrite(13, HIGH);
    delay(50);
    digitalWrite(13, LOW);

    return;
  }

  // heartbeat blinkenlight on fail
  unsigned int mils;
  while( true ) {
    mils = millis() % 500;
    if (mils > 100 && mils < 150 ||
        mils > 200 && mils < 250
    ) {
      digitalWrite(13, true);
    } else {
      digitalWrite(13, false);
    }
  }
}

// Test dispatch method which activates individual test groups
bool test(){
  return test_tests() && test_state_machine() && test_gps() && test_music();
}

/* Should be hooked into setup() like this: */

void setup(){
  Serial.begin(115200);
  pinMode(13, OUTPUT);
  test_lock();
}




/*
 * Project specific tests. Example pulled from github.com/robacarp/ringbox_puzzle :
 */


bool test_state_machine() {
  // not passing initially
  assert( ! password.completed() );

  // random advances don't do anything
  password.advance_state(0x8);
  password.advance_state(0x3);
  assert( password.current_state() == 0 );

  // advancing state once, then resetting with an incorrect value
  password.advance_state(0x1);
  assert( password.current_state() == 1 );
  password.advance_state(0x8);
  assert( password.current_state() == 0 );

  // the first number multiple times
  password.advance_state(0x1);
  password.advance_state(0x1);
  assert( password.current_state() == 1 );
  password.advance_state(0x1);
  assert( password.current_state() == 1 );

  // first, second, third, first
  password.advance_state(0x1);
  assert( password.current_state() == 1 );
  assert( ! password.completed() );

  password.advance_state(0x2);
  assert( password.current_state() == 2 );
  assert( ! password.completed() );

  password.advance_state(0x4);
  assert( password.current_state() == 3 );
  assert( ! password.completed() );

  password.advance_state(0x1);
  assert( password.current_state() == 1 );
  assert( ! password.completed() );

  // correct password
  password.reset();
  assert( ! password.completed() );

  password.advance_state(0x1);
  password.advance_state(0x2);
  password.advance_state(0x4);
  password.advance_state(0x8);
  assert( password.current_state() >= 4 );

  assert( password.completed() );

  password.reset();

  return tests_pass;
}

// Negative Longitude is West.
// Negative Latitude is South.
// Testing the haversine to be accurate to <1% error
bool test_gps(){
  double distance, lat_a, lon_a, lat_b, lon_b, lat_c, lon_c, expected, delta;
  // 41.6076N, 88.2037W
  // 35.1346N, 85.3584W
  // 760.2 km says wolframalpha
  lat_a = 41.6076;
  lon_a = -88.2037;
  lat_b = 35.1346;
  lon_b = -85.3584;
  distance = GPS::coordinate_distance(lat_a, lon_a, lat_b, lon_b);
  expected = 760.2;
  delta = 760.2 - distance;
  assert(delta / expected < 0.01);

  // 41.6076N, 88.2037W
  // 41.6507N, 88.2555W
  // 6.442 km
  lat_a = 41.6076;
  lon_a = -88.2037;
  lat_b = 41.6507;
  lon_b = -88.2555;
  distance = GPS::coordinate_distance(lat_a, lon_a, lat_b, lon_b);
  expected = 6.442;
  delta = expected - distance;
  assert(delta / expected < 0.01);


  // test that we can enter the target destination and we actually unlock
  lat_c = 35.1346;
  lon_c = -85.3584;

  gps.target_latitude = lat_a;
  gps.target_longitude = lon_a;
  gps.precision = 3;
  gps.sentences = 3;

  // ~760km
  gps.latitude = lat_c;
  gps.longitude = lon_c;
  gps.distance_to_target();
  assert( ! gps.at_target() );

  // ~6km
  gps.latitude = lat_b;
  gps.longitude = lon_b;
  gps.distance_to_target();
  assert( ! gps.at_target() );

  // <1km
  gps.latitude = lat_a;
  gps.longitude = lon_a;
  gps.distance_to_target();
  assert( gps.at_target() );

  return tests_pass;
}

bool test_music(){
  assert( C == 32.7 );
  assert( NOTE(C, 2) == 65.4 );
  assert( NOTE(A, 4) == 440.0 );
  assert( PWM_WAIT( NOTE( C, 3 ) ) == 3822 );
  assert( PWM_WAIT( NOTE( A, 4 ) ) == 1136 );
  return tests_pass;
}

As with every time I’ve had a suite of tests for a project I was working on, the time saved was far more than the time spent. Little tweaks to different algorithms have knock on effects that aren’t easily reasoned about.


Date: 2015-Jun-29
Tags: arduino testing
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This page was originally published as a github gist and was imported in December 2017.
Original Gist here.