Elixir Test Output

Elixir has been designed taking inspiration from a number of other languages. This makes the developer experience to be one of the best available. This includes test runner support and the ever useful mix utility that hosts everything from project creation, dependency management, database migrations and repl support.

One feature that is slightly lagging is the test output support. Previously I had worked in Groovy using Gradle and Spock. The test output report was spectacular. You could generate a detailed report artifact, which was either a directory of html or a single zip file containg the same. This report would list all of the test suites with the ability to see the associated console output with the test. This becomes great to have in a CI setup as these can cheaply be stored in S3 which allows detailed investigation of historical failed test runs.

The following provides the hooks to improve the Elixir story. I have been considering writing one that produces a livebook as the output.

https://stackoverflow.com/q/41350135/662571

Here is a sample project that uses some of the above techniques:

https://github.com/chriseyre2000/my_custom_test_formatter

Currently the project will add the name of the current project before the summary line of tests passed and failed.
The idea being that an umbrella project could report which project it was. This can make life a bit easier when dealing with a build server that only shows a limited span around failures.

Thoughts on CQRS ES

The theory goes that an event sourced system has a perfect audit trail. However in practice this is only partially true.

It does have a complete history of all of the commands that have succeeded. It tells you nothing of the load on the read model and the failed commands. These require more detailed information that may reside in your observability system.

Helm

I am beginning to explore Helm now that I have access to a Kubernetes system.

Helm is the release manager for K8S. You use this to deploy “releases” to a Kubernetes envionment.

It’s amazing the amount of useful info that is returned.

helm get – returns the list of currently deployed releases.

You need helm get -a to include the ones that have failed to deploy.

helm get values <release name>

or

helm get manifest <release name>

reveal much of the details of the infrastructure.

I hope to turn this into a visualization.

Documenting CQRS ES

I have been looking for a decent template to document CQRS ES.
I think I have found one: https://github.com/tmorin/plantuml-libs

The following diagram:

This was generated using plantuml from the following source:

@startuml
' configures the library

' loads the library's bootstrap
!include https://raw.githubusercontent.com/tmorin/plantuml-libs/master/distribution/bootstrap.puml

!include https://raw.githubusercontent.com/tmorin/plantuml-libs/master/distribution/eventstorming/bootstrap.puml

' loads the package bootstrap

' include elements
include('eventstorming/Element/FacadeCommand')
include('eventstorming/Element/Command')
include('eventstorming/Element/Result')
include('eventstorming/Element/Event')
include('eventstorming/Element/DomainEvent')
include('eventstorming/Element/IntegrationEvent')
include('eventstorming/Element/Query')
include('eventstorming/Element/ReadModel')
include('eventstorming/Element/UserInterface')
include('eventstorming/Element/Aggregate')
include('eventstorming/Element/Service')
include('eventstorming/Element/Policy')
include('eventstorming/Element/Saga')
include('eventstorming/Element/Process')
include('eventstorming/Element/Timer')
include('eventstorming/Element/Person')
include('eventstorming/Element/System')
include('eventstorming/Element/Comment')

' display elements
FacadeCommand('FacadeCommand')
Command('Command')
Result('Result')
Event('Event')
DomainEvent('DomainEvent')
IntegrationEvent('IntegrationEvent')
Query('Query')
ReadModel('ReadModel')
UserInterface('UserInterface')
Aggregate('Aggregate')
Service('Service')
Policy('Policy')
Saga('Saga')
Process('Process')
Timer('Timer')
Person('Person')
System('System')
Comment('Comment')

@enduml

The advantage of this is that it does not require a local copy of the project.

The downside is that it requires an internet connection, and is at risk of the project being moved.
I can see myself making use of this.

I have forked this project so that I can have a guaranteed stable location and use a single file.

This reduces the above to:

@startuml

!include https://raw.githubusercontent.com/chriseyre2000/plantuml-libs/master/distribution/eventstorming/eventstorming.puml

' display elements
FacadeCommand('FacadeCommand')
Command('Command')
Result('Result')
Event('Event')
DomainEvent('DomainEvent')
IntegrationEvent('IntegrationEvent')
Query('Query')
ReadModel('ReadModel')
UserInterface('UserInterface')
Aggregate('Aggregate')
Service('Service')
Policy('Policy')
Saga('Saga')
Process('Process')
Timer('Timer')
Person('Person')
System('System')
Comment('Comment')

@enduml

Are The Inmates In Charge Of The Asylum?

The UK currently has a cost of living crisis. Inflation is going through the roof and the only think being done to influence this is to put up interest rates! The argument for this is that if credit becomes more expensive people will reduce what they are spending. Are economists so stuck in 1970’s models that they can see nothing else?

Credit card use is not rising because credit is cheap, they are rising because costs are escalating. Adding to the interest on mortgages and credit cards won’t help control this. This will drive workers to ask for larger pay rises and will fix the interest rate growth as permanent.

Fuel price rises have a massive effect across the whole supply chain. We had protests in the UK when petrol first reached 1 GBP per litre, we are now at around 1.85 GBP.

We have a leadership contest going on between two people who are denying reality and aiming for the votes of a very small electorate. Neither candidate has a sensible plan (or indeed a mandate). One wants to control inflation and the other wants to cut tax.