cpptraining.CucumberExamplesCallingCpp

Install ruby
Install cucumber gem
Install gherkin gem
Install rspec gem

Starting with Cucumber

Create a directory to store your work
In that directory, type cucumber:

C:\learncpp>mkdir ruby_cpp
C:\learncpp>cd ruby_cpp
C:\learncpp\ruby_cpp>cucumber
You don't have a 'features' directory.  Please create one to get started.
See http://cukes.info/ for more information.

C:\learncpp\ruby_cpp>

Create a directory called “features”
Create a feature description file in the “features” directory called rpncalc_basic_operations.feature: rpncalc_basic_operations.feature

Feature: Basic Operations
  Scenario Outline: Perform some of the basic operations
  Given the input "<input>"
  When the calculator performs "<operator>" 
  Then the result should be "<output>"
  Examples:
  | input | operator      | output  |
  | 30 4  | +             | 34      |
  | 30 4  | -             | 26      |
  | 5     | !             | 120     |
  | 4 6   | *             | 24      |
  | 8 2   | /             | 4       |
  | 1     | -             | -1      |
  |       | +             | 0       |
  | 8 0   | /             | <error> |
  |       | $%^unknown*&^ | <error> |

Run cucumber again, it will report missing steps. Copy those code examples;

You can implement step definitions for undefined steps with these snippets:

Given /^the input "([^"]*)"$/ do |arg1|
  pending # express the regexp above with the code you wish you had
end

When /^the calculator performs "([^"]*)"$/ do |arg1|
  pending # express the regexp above with the code you wish you had
end

Then /^the result should be "([^"]*)"$/ do |arg1|
  pending # express the regexp above with the code you wish you had
end

If you want snippets in a different programming language, just make sure a file
with the appropriate file extension exists where cucumber looks for step definitions.

Under the features directory create a directory called step_definitions
In the step_definitions directory create a file called rpncalc_steps.rb rpncalc_steps.rb

Given /^the input "([^"]*)"$/ do |arg1|
  pending # express the regexp above with the code you wish you had
end

When /^the calculator performs "([^"]*)"$/ do |arg1|
  pending # express the regexp above with the code you wish you had
end

Then /^the result should be "([^"]*)"$/ do |arg1|
  pending # express the regexp above with the code you wish you had
end

Creating the basic glue code

Create a file in the top-level directory called extconf.rb: extconf.rb

require 'mkmf'
dir_config("fixture_glue")
create_makefile("fixture_glue")

Create a file called fixture_glue.cpp: fixture_glue.cpp

#include "ruby.h"
 
using namespace std;
#include <stdio.h>
 
VALUE cRpnCalcFixture;
 
class RpnCalc {
  // this will actually be a production-class linked in
  // from a dynamic or static library (later)
};
 
 
void RpnCalcFixture_Dispose(void *c) {
    printf("Deleting calc\n");
    delete static_cast<RpnCalc*>(c);
}
 
VALUE RpnCalcFixture_New(VALUE clazz) {
    printf("Creating calc\n");
    RpnCalc *c = new RpnCalc;    
    VALUE tdata = Data_Wrap_Struct(clazz, 0, RpnCalcFixture_Dispose, c);
    rb_obj_call_init(tdata, 0, 0);
    return tdata;
}
 
VALUE RpnCalcFixture_Enter(VALUE self, VALUE value) {
    printf("Enter value: %d\n", NUM2INT(value));
    return Qnil;
}
 
VALUE RpnCalcFixture_Perform(VALUE self, VALUE operatorName) {
    printf("Performing: %s\n", RSTRING_PTR(operatorName));
    return Qnil;
}
 
VALUE RpnCalcFixture_X(VALUE self) {
    printf("Getting x\n");
    return INT2NUM(12);
}
 
extern "C" {
typedef VALUE(*V_F)(...);
void Init_fixture_glue() {
    cRpnCalcFixture = rb_define_class("RpnCalcFixture", rb_cObject);
    rb_define_singleton_method(
		    cRpnCalcFixture, "new", (V_F)RpnCalcFixture_New, 0);
    rb_define_method(cRpnCalcFixture, "x", (V_F)RpnCalcFixture_X, 0);
    rb_define_method(cRpnCalcFixture, "perform",(V_F)RpnCalcFixture_Perform, 1);
    rb_define_method(cRpnCalcFixture, "enter", (V_F)RpnCalcFixture_Enter, 1);
}
}

Build and install

C:\learncpp\ruby>make
g++ -I. -IC:/Ruby192/include/ruby-1.9.1/i386-mingw32 -I/C/Ruby192/include/ruby-1
...<snip>...
auto-image-base,--enable-auto-import fixture_glue-i386-mingw32.def  -lmsvcrt-rub
y191  -lshell32 -lws2_32

C:\learncpp\ruby>make install
/usr/bin/install -c -m 0755 fixture_glue.so C:/Ruby192/lib/ruby/site_ruby/1.9.1/
i386-msvcrt

C:\learncpp\ruby>

Connecting to the glue code

Update your rpncalc_steps.rb:

require 'fixture_glue'

Given /^the input "([^"]*)"$/ do |arg1|
  @calc = RpnCalcFixture.new
  arg1.split(/ /).collect{|s| @calc.enter(s.to_i)}
end

When /^the calculator performs "([^"]*)"$/ do |arg1|
  @calc.perform(arg1)
end

Then /^the result should be "([^"]*)"$/ do |arg1|
  # this should call getX, but the real calc is not implemented
end

Re-run cucumber:

C:\learncpp\ruby_cpp>cucumber
Feature: Basic Operations

  Scenario Outline: Perform some of the basic operations # features\rpncalc_basi
c_operations.feature:2
    Given the input "<input>"                            # features/step_definit
ions/rpncalc_steps.rb:3
    When the calculator performs "<operator>"            # features/step_definit
ions/rpncalc_steps.rb:8
    Then the result should be "<output>"                 # features/step_definit
ions/rpncalc_steps.rb:12

    Examples:
      | input | operator      | output  |
      |Creating calc
Enter value: 30
Enter value: 4
Performing: +
 30 4  | +             | 34      |
      |Creating calc
Enter value: 30
Enter value: 4
Performing: -
 30 4  | -             | 26      |
      |Creating calc
Enter value: 5
Performing: !
 5     | !             | 120     |
      |Creating calc
Enter value: 4
Enter value: 6
Performing: *
 4 6   | *             | 24      |
      |Creating calc
Enter value: 8
Enter value: 2
Performing: /
 8 2   | /             | 4       |
      |Creating calc
Enter value: 1
Performing: -
 1     | -             |Deleting calc
Deleting calc
Deleting calc
Deleting calc
Deleting calc
 -1      |
      |Creating calc
Performing: +
       | +             | 0       |
      |Creating calc
Enter value: 8
Enter value: 0
Performing: /
 8 0   | /             | <error> |
      |Creating calc
Performing: $%^unknown*&^
       | $%^unknown*&^ | <error> |

9 scenarios (9 passed)
27 steps (27 passed)
0m0.031s
Deleting calc
Deleting calc
Deleting calc
Deleting calc

Preliminary Setup

Starting with Cucumber

Creating the basic glue code

Connecting to the glue code

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