Testing Embedded Systems With Cucumber Cucumber isn't just for web apps. You can test just about anything with it—including embedded systems! In this talk, we'll look at several different facets of driving hardware from Cucumber, including: Connecting to an Arduino using a custom serial protocol Taking advantage of the TCP stack when it's available Building the Cucumber wire protocol into your device What to do when you can't modify the app under test Driving more fully-featured devices such as the BeagleBone or RaspberryPi By the end of the presentation, you'll have a handle on what the various options are for testing embedded devices, and which tradeoffs will apply to your system.

1. Testing Embedded Systems
With Cucumber
Ian Dees • @undees
CukeUp! NYC 2013

2. Plenty of Ruby, but...

3. There will be C

4. There will be C++

5. There will be C#

6. http://pragprog.com/
titles/dhwcr
discount code:
CucumberIanDees

8. The Embedded
Continuum

9. almost a
computer
chip and
some ROM

10. Simple devices
No Ruby, no Cucumber

11. Gray Code
A simple system to test

12. Feature: Gray Code
Scenario Outline: Counter
When I press the button
Then the LEDs should read "<leds>"
Examples:
| leds |
| ..O |
| .OO |
| .O. |
| OO. |
| OOO |
| O.O |
| O.. |
| ... |

13. Arduino

14. void loop() {
button.update();
bool buttonPressed = button.risingEdge();
if (buttonPressed) {
counter = (counter + 1) % ENTRIES;
updateLeds();
}
delay(50);
}

15. Drive code directly

16. void loop() {
button.update();
bool buttonPressed = button.risingEdge();
if (buttonPressed) {
counter = (counter + 1) % ENTRIES;
updateLeds();
}
delay(50);
}

17. void loop() {
button.update();
bool buttonPressed = button.risingEdge();
if (buttonPressed) {
counter = (counter + 1) % ENTRIES;
updateLeds();
}
delay(50);
}

18. static bool isFakeButtonPressed;
class Bounce {
public:
// ...
bool risingEdge() {
bool result = isFakeButtonPressed;
isFakeButtonPressed = false;
return result;
}
};

19. extern "C" void press() {
isFakeButtonPressed = true;
}

20. const char* leds() {
static char buf[LEDS + 1] = {0};
for (int i = 0; i < LEDS; ++i) {
buf[i] = STATES[counter][i] == HIGH ?
'O' :
'.';
}
return buf;
}

21. https://github.com/ffi/ffi
FFI

22. require 'ffi'
module Arduino
extend FFI::Library
ffi_lib 'graycode'
attach_function :press, [], :void
attach_function :leds, [], :string
attach_function :setup, [], :void
attach_function :loop, [], :void
end

23. When /^I press the button$/ do
Arduino.press
Arduino.loop
end
Then /^the LEDs should read "(.*?)"$/ do
|leds|
expect(Arduino.leds).to eq(leds)
end

24. Cucumber Wire Protocol

25. Cucumber-CPP
https://github.com/cucumber/cucumber-cpp

26. host: localhost
port: 3902
features/step_definitions/cucumber.wire

27. When /^I press the button$/ do
Arduino.press
Arduino.loop
end
Then /^the LEDs should read "(.*?)"$/ do
|expected|
expect(Arduino.leds).to eq(expected)
end

28. WHEN("^I press the button$") {
press();
loop();
}
THEN("^the LEDs should read "(.*?)"$") {
REGEX_PARAM(string, expected);
BOOST_CHECK_EQUAL(leds(), expected);
}

29. Bespoke wire server

30. http://www.2600.com/code/212/listener.c
listen/accept/read/write

31. while(fgets(buf,sizeof buf,rStream)) {
respond_to_cucumber(wStream, buf);
}

32. step_matches
invoke
Two messages

33. Then the LEDs should read "..O"
➡
["step_matches",
{"name_to_match":
"the LEDs should read"}]
➡
["success",
[{"id":"1",
"args":[{"val":"..O",
"pos":"22"}]}]]

34. json spirit
http://www.codeproject.com/KB/recipes/
JSON_Spirit.aspx

35. extern "C" void respond_to_cucumber(
FILE* stream,
const char* message) {
string s = message;
Value v;
read(s, v);
Array& a = v.get_array();
string type = a[0].get_str();
// handle Cucumber message types
report_success(stream);
}

36. if (type == "step_matches") {
string name = step_name(v);
if (name == "I press the button") {
report_success(stream);
return;
} else if (...)
// ...
}
}

37. if (type == "step_matches") {
string name = step_name(v);
if (name == "I press the button") {
report_success(stream);
return;
} else if (...)
// ...
}
}

38. if (type == "step_matches") {
string name = step_name(v);
if (...) {
// ...
} else if (name.find("the LEDs") == 0)
const int START = 22;
string leds = name.substr(START, 3);
report_match(leds, START, stream);
return;
}
}

39. Then the LEDs should read "..O"
➡
["invoke",
{"id":"1",
"args":["..O"]}]
➡
["success", []]

40. if (type == "invoke") {
string id = step_id(v);
if (id == "0") {
press();
loop();
} else if (id == "1") {
// ...
}
}
}

41. if (type == "invoke") {
string id = step_id(v);
if (id == "0") {
press();
loop();
} else if (id == "1") {
// ...
}
}
}

42. if (type == "invoke") {
string id = step_id(v);
if (id == "0") {
// ...
} else if (id == "1") {
string expected = step_leds(v);
if (expected != leds()) {
report_failure("LEDs", stream);
return;
}
}
}

43. https://github.com/hparra/ruby-serialport
Serial

44. void loop() {
button.update();
bool buttonPressed = button.risingEdge();
if (buttonPressed) {
counter = (counter + 1) % ENTRIES;
updateLeds();
}
delay(50);
}

45. void loop() {
button.update();
bool buttonPressed = button.risingEdge();
if ( buttonPressed ) {
counter = (counter + 1) % ENTRIES;
updateLeds();
delay(50);
}

46. void loop() {
button.update();
bool buttonPressed = button.risingEdge();
int command = (Serial.available() > 0 ?
Serial.read() :
-1);
if (isIncrement(buttonPressed, command)) {
counter = (counter + 1) % ENTRIES;
updateLeds();
} else if (isQuery(command)) {
Serial.write(leds());
Serial.write('n');
}
delay(50);
}

47. void loop() {
button.update();
bool buttonPressed = button.risingEdge();
int command = (Serial.available() > 0 ?
Serial.read() :
-1);
if (isIncrement(buttonPressed, command)) {
counter = (counter + 1) % ENTRIES;
updateLeds();
} else if (isQuery(command)) {
Serial.write(leds());
Serial.write('n');
}
delay(50);
}

48. void loop() {
button.update();
bool buttonPressed = button.risingEdge();
int command = (Serial.available() > 0 ?
Serial.read() :
-1);
if (isIncrement(buttonPressed, command)) {
counter = (counter + 1) % ENTRIES;
updateLeds();
} else if (isQuery(command)) {
Serial.write(leds());
Serial.write('n');
}
delay(50);
}

49. void loop() {
button.update();
bool buttonPressed = button.risingEdge();
int command = (Serial.available() > 0 ?
Serial.read() :
-1);
if (isIncrement(buttonPressed, command)) {
counter = (counter + 1) % ENTRIES;
updateLeds();
} else if (isQuery(command)) {
Serial.write(leds());
Serial.write('n');
}
delay(50);
}

50. require 'serialport'
module Arduino
@@port = SerialPort.open 2, 9600
at_exit { @@port.close }
def self.press
@@port.write '+'
end
def self.leds
@@port.write '?'
@@port.read.strip
end
end

51. Ruby, C#, SpecFlow, Cucumber
Almost a computer

52. Feature: Calculator
Scenario: Add two numbers
When I multiply 2 and 3
Then I should get 6

53. Run Cucumber directly

54. rsync -av --delete . remote1:test_path
ssh remote1 'cd test_path && cucumber'

55. Drive the GUI

56. TestStack White
https://github.com/TestStack/White

57. namespace Calc.Spec
{
[Binding]
public class CalculatorSteps
{
private Window window;
[Before]
public void Before()
{
Application application =
Application.Launch("calc.exe");
window =
application.GetWindow(
"Calculator",
InitializeOption.NoCache);
}
// ...
}
}

58. namespace Calc.Spec
{
[Binding]
public class CalculatorSteps
{
private Window window;
[Before]
public void Before()
{
Application application =
Application.Launch("calc.exe");
window =
application.GetWindow(
"Calculator",
InitializeOption.NoCache);
}
// ...
}
}

59. namespace Calc.Spec
{
[Binding]
public class CalculatorSteps
{
private Window window;
[Before]
public void Before()
{
Application application =
Application.Launch("calc.exe");
window =
application.GetWindow(
"Calculator",
InitializeOption.NoCache);
}
// ...
}
}

60. [When(@"I multiply (.*) and (.*)")]
public void WhenIMultiply(string a, string b)
{
window.Keyboard.Enter(a + "*" + b + "=");
}
[Then(@"I should get (.*)")]
public void ThenIShouldGet(string expected)
{
window.Get<Label>(expected);
}

61. Give your app an API

62. Mongoose web server

63. int main()
{
struct mg_context *ctx = mg_start();
mg_set_option(ctx, "ports", "33333");
mg_set_uri_callback(ctx, "/",
&show_index, 0);
mg_set_uri_callback(ctx, "/multiply",
&multiply, 0);
mg_set_uri_callback(ctx, "/result",
&get_result, 0);
getchar();
mg_stop(ctx);
return 0;
}

64. int main()
{
struct mg_context *ctx = mg_start();
mg_set_option(ctx, "ports", "33333");
mg_set_uri_callback(ctx, "/",
&show_index, 0);
mg_set_uri_callback(ctx, "/multiply",
&multiply, 0);
mg_set_uri_callback(ctx, "/result",
&get_result, 0);
getchar();
mg_stop(ctx);
return 0;
}

65. static void multiply(
struct mg_connection *conn,
const struct mg_request_info *request_info,
void *user_data)
{
char *ap = mg_get_var(conn, "multiplier");
char *bp = mg_get_var(conn, "multiplicand");
int a = atol(ap);
int b = atol(bp);
result = a * b;
mg_printf(conn,
"HTTP/1.1 200 OKrn
Content-Type: text/plainrnrn");
mg_free(multiplier_s);
mg_free(multiplicand_s);
}

66. static void multiply(
struct mg_connection *conn,
const struct mg_request_info *request_info,
void *user_data)
{
char *ap = mg_get_var(conn, "multiplier");
char *bp = mg_get_var(conn, "multiplicand");
int a = atol(ap);
int b = atol(bp);
result = a * b;
mg_printf(conn,
"HTTP/1.1 200 OKrn
Content-Type: text/plainrnrn");
mg_free(multiplier_s);
mg_free(multiplicand_s);
}

67. static void multiply(
struct mg_connection *conn,
const struct mg_request_info *request_info,
void *user_data)
{
char *ap = mg_get_var(conn, "multiplier");
char *bp = mg_get_var(conn, "multiplicand");
int a = atol(ap);
int b = atol(bp);
result = a * b;
mg_printf(conn,
"HTTP/1.1 200 OKrn
Content-Type: text/plainrnrn");
mg_free(multiplier_s);
mg_free(multiplicand_s);
}

68. static void multiply(
struct mg_connection *conn,
const struct mg_request_info *request_info,
void *user_data)
{
char *ap = mg_get_var(conn, "multiplier");
char *bp = mg_get_var(conn, "multiplicand");
int a = atol(ap);
int b = atol(bp);
result = a * b;
mg_printf(conn,
"HTTP/1.1 200 OKrn
Content-Type: text/plainrnrn");
mg_free(multiplier_s);
mg_free(multiplicand_s);
}

69. static void get_result(
struct mg_connection *conn,
const struct mg_request_info *request_info,
void *user_data)
{
mg_printf(conn,
"HTTP/1.1 200 OKrn
Content-Type: text/plainrnrn%d",
result);
}

70. https://github.com/jnunemaker/httparty
HTTParty

71. When(/^I multiply (d+) and (d+)$/) do |a, b|
Calculator.multiply a, b
end
Then(/^I should get (d+)$/) do |n|
expect(Calculator.result).to eq(n.to_i)
end

72. require 'httparty'
class Calculator
include HTTParty
base_uri 'localhost:33333'
def self.multiply(a, b)
get "/multiply?multiplier=#{a}
&multiplicand=#{b}"
end
def self.result
get("/result").to_i
end
end

73. (because tl;dr is passé)
In summary:

74. Have source? Device Technique
yes simple Direct
yes simple Serial
yes medium
Cucumber Wire
Protocol
yes powerful Custom TCP
no powerful GUI

75. Thank you
https://github.com/undees/cukeup