Loïc Faugeron Technical Blog

In this series we're building the software of a Mars Rover, according to the following specifications. It allows us to practice the followings:

• Monolithic Repositories (MonoRepo)
• Command / Query Responsibility Segregation (CQRS)
• Event Sourcing (ES)
• Test Driven Development (TDD)

We've already developed the first use case about landing the rover on mars, and the second one about driving it. We're now developing the last one, requesting its location:

Mars rover will be requested to give its current location (x and y coordinates and the orientation).

In this article we're going to create a new package for the geolocation value objects (Location, Coordinates and Orientation).

Creating the geolocation package

We can start by creating the directory:

git checkout 5-location
mkdir -p packages/geolocation
cd packages/geolocation

Composer needs us to set up the package by creating a composer.json file:

{
    "name": "mars-rover/geolocation",
    "license": "MIT",
    "type": "library",
    "description": "Mars Rover - Geolocation",
    "autoload": {
        "psr-4": { "MarsRover\\Geolocation\\": "src/MarsRover/Geolocation" }
    },
    "require": {
        "php": "^7.0"
    },
    "require-dev": {
        "memio/spec-gen": "^0.6"
    }
}

We've decided to use phpspec as a test framework, and to get the most of it we'd like to use its SpecGen extension. To do so we need to create the phpspec.yml.dist file:

extensions:
    Memio\SpecGen\MemioSpecGenExtension: ~

Note: For more information about phpspec see this article.

Finally, we can configure this package's git by creating a .gitignore file:

# Configuration
/phpspec.yml

# Third Party libraries
/vendor/
/composer.lock

With this we've finished creating our package. We can run Composer:

composer install --optimize-autoloader

That should be enough for a first commit:

git add -A
git commit -m '5: Created Geolocation package'

Adding geolocation to the project

Let's go back to the project's root:

cd ../../

All we need to do is to add a new line in the require section of our composer.json file:

{
    "name": "mars-rover/mars-rover",
    "license": "MIT",
    "type": "project",
    "description": "Mars Rover",
    "repositories": [
        {
            "type": "path",
            "url": "./packages/*"
        }
    ],
    "require": {
        "mars-rover/event-sourcing": "*@dev",
        "mars-rover/geolocation": "*@dev",
        "mars-rover/location": "*@dev",
        "mars-rover/navigation": "*@dev",
        "php": "^7.0"
    },
    "require-dev": {
        "phpspec/phpspec": "^3.0"
    }
}

Actually, we also need to add a new section in phpspec.yml.dist:

suites:
    event-sourcing:
        namespace: 'MarsRover\EventSourcing'
        src_path: packages/event-sourcing/src
        spec_path: packages/event-sourcing

    geolocation:
        namespace: 'MarsRover\Geolocation'
        src_path: packages/geolocation/src
        spec_path: packages/geolocation

    location:
        namespace: 'MarsRover\Location'
        src_path: packages/location/src
        spec_path: packages/location

    navigation:
        namespace: 'MarsRover\Navigation'
        src_path: packages/navigation/src
        spec_path: packages/navigation

And that's it! We are now able to run Composer and then phpspec:

composer update --optimize-autoloader
vendor/bin/phpspec run

That should be enough for a second commit:

git add -A
git commit -m '5: Added geolocation package to main project'

Adding geolocation to navigation

Now let's go to the navigation package:

cd packages/navigation

All we need to do is to add a new line in the require section of our composer.json file:

{
    "name": "mars-rover/navigation",
    "license": "MIT",
    "type": "library",
    "description": "Mars Rover - Navigation",
    "autoload": {
        "psr-4": { "MarsRover\\Navigation\\": "src/MarsRover/Navigation" }
    },
    "repositories": [
        {
            "type": "path",
            "url": "../*"
        }
    ],
    "require": {
        "mars-rover/event-sourcing": "*@dev",
        "mars-rover/geolocation": "*@dev",
        "php": "^7.0"
    },
    "require-dev": {
        "memio/spec-gen": "^0.6"
    }
}

And that's it! We are now able to run Composer and then phpspec:

composer update --optimize-autoloader
vendor/bin/phpspec run

That should be enough for a third commit:

git add -A
git commit -m '5: Added geolocation package to navigation package'

Adding geolocation to location

Now let's go to the location package:

cd ../location

This time, in addition to a new line in the require section we also need to add a new repositories section to our composer.json file:

{
    "name": "mars-rover/location",
    "license": "MIT",
    "type": "library",
    "description": "Mars Rover - Location",
    "autoload": {
        "psr-4": { "MarsRover\\Location\\": "src/MarsRover/Location" }
    },
    "repositories": [
        {
            "type": "path",
            "url": "../*"
        }
    ],
    "require": {
        "mars-rover/geolocation": "*@dev",
        "php": "^7.0"
    },
    "require-dev": {
        "memio/spec-gen": "^0.6"
    }
}

And that's it! We are now able to run Composer and then phpspec:

composer update --optimize-autoloader
vendor/bin/phpspec run

That should be enough for a fourth and last commit:

git add -A
git commit -m '5: Added geolocation package to location package'

Conclusion

We've now created a geolocation package that is shared between navigation and location, keeping them both separate.

What's next

In the next article, we'll start moving our value objects to our new package.