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README.md

aceptadora

lint acceptance Travis build status

Aceptadora provides the boilerplate to orchestrate the containers for an acceptance test.

Aceptadora is a replacement for docker-compose in acceptance tests, and it also allows running and debugging tests from your IDE.

Example

The acceptance tests of this package are an example of usage for this package. There are also CI builds running on both Github Actions and Travis CI that serve as an example.

Long story short:

  • Define your service in a YAML file inspired by docker-compose format, with an idiomatic name of aceptadora.yml
  • Define your environment variables in some config.env files
  • Load them in your test:
   aceptadora.SetEnv(
   	s.T(),
   	aceptadora.OneOfEnvConfigs(
   		aceptadora.EnvConfigWhenEnvVarPresent("../config/gitlab.env", "GITLAB_CI"),
   		aceptadora.EnvConfigAlways("../config/default.env"),
   	),
   	aceptadora.EnvConfigAlways("acceptance.env"),
   ) 
  • Fill the aceptadora.Config values, you can use github.com/colega/envconfig for that
   envconfig.MustProcess("ACCEPTANCE", &s.cfg)
  • Instantiate the aceptadora:
   aceptadora := aceptadora.New(t, cfg)
  • Start your service:
   aceptadora.Run(ctx, "redis")
  • Test stuff
  • When you're done, stop it using aceptadora.StopAll(ctx) or aceptadora.Stop(ctx, "redis")

Motivations

We've been using docker-compose for acceptance tests for a long time, and while this approach did have issues (since test subjects and dependencies were not restarted between tests, we had to have some suites depending on other ones, which made the tests flaky and slow) we lived with it until the introduction of gRPC. Once we started playing with gRPC we found an issue: the gRPC golang client tries to connect to the service when the service is started, and if it fails, it will keep returning that error for a while. Since we started our test subjects before the acceptance-tester in the former approach, our test subjects failed to call the mocked gRPC servers on the acceptance-tester.

So, we created a library that restarted our test subject interacting with docker from the acceptance test itself.

Then, we found the need to restart multiple test subjects plus the complexity of having to handle two kinds of configurations (docker-compose for dependencies and aceptadora for test subjects) so we decided to extend the functionality of aceptadora to completely replace the docker-compose and allow managing the lifecycle of all dependencies from the test.

You can read the full story on Medium.

Decisions

Everything in aceptadora accepts t *testing.T and everything does require.NoError(t, err) because in tests nobody's going to handle the errors anyway, so we apply a fail-fast strategy, removing the retured errors and keeping the API clean for clearer acceptance tests.

Running

In order to handle multiple environments there are some stages in config loading. Notice that all the configs loaded expand the env vars set by ${VAR} to their values from what's already loaded.

First, we load some very basic env-dependant config, deciding on env vars to load a local or gitlab config. This configuration mostly provides details about networking setup:

  • Where can acceptance-tester reach the services? Usually this would be localhost, but on Gitlab it's docker as we're running dind.
  • Where can services reach the acceptance-tester? This will be set to the first local non-loopback IP address in the environment variable called TESTER_ADDRESS. You can set this variable to something more specific before running the test too, in which case it won't be overwritten.

One may wonder: why don't we just decide all of that in some kind of test-loading shellscript? The answer is that deciding that from the test itself allows us running the tests from any IDE as a normal test, instead of having a proxy script. Of course loading some env vars would work, but since aceptadora can do this for you, why should we care? This way we can make sure that test running is portable and doesn't require any external dependencies.

Then we load more env configs for the test itself, usually acceptance.env, which tells the acceptance test where the aceptadora.yml file is located, and how images from different docker registries are pulled. Notice that acceptance.env can be specific to each suite you may have if their paths are different. You can load as many common configs as you want, loading an acceptance.env and then ../config/acceptance.env for example.

Here aceptadora.New() would load the aceptadora.yml file from the provided dir and filename, and it will also set ${YAMLDIR} variable for the yamls itself to be able to reference its configs and binds from where the yaml is located instead of from where the test is located: this allows us having multiple test suites in different folders using the same aceptadora.yml file.

Finally, we run services by just running aceptadora.Run(ctx, "svc-name-in-the-yaml").

Aceptadora will also take care of stopping the services, you can call aceptadora.Stop(ctx, svcName) to stop one of them, or StopAll(ctx) to stop all the (still running) services.

Unit tests

This package doesn't have unit tests. All the testing is performed by the example itself in the acceptance tests folder. The unit tests would require either defining interfaces for the functionality that docker provides and mocking them, which would overcomplicate the code without offering enough value in exchange, or testing using the docker real docker API, which is already covered by the acceptance tests. However, this is opinionated. Feel free to disagree, open us an issue with your proposal, or even better, a pull request.

About

Aceptadora provides the boilerplate to orchestrate the containers for an acceptance test.

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