Allow configuring the AlwaysPullPolicy

[sebastian-steiner]

This PR fixes a bug that did not allow configuring the default provided AlwaysPullPolicy through the properties files.

Previous behavior

When trying to configure the following testcontainers.properties:

pull.policy=org.testcontainers.images.CustomAlwaysPullPolicy

Running tests would fail with the following exception, because the configuration couldn't access the package-private constructor:

Configured ImagePullPolicy could not be loaded: org.testcontainers.images.AlwaysPullPolicy
java.lang.IllegalArgumentException: Configured ImagePullPolicy could not be loaded: org.testcontainers.images.AlwaysPullPolicy
	at org.testcontainers.images.PullPolicy.defaultPolicy(PullPolicy.java:46)
	at org.testcontainers.images.RemoteDockerImage.<init>(RemoteDockerImage.java:47)
	at org.testcontainers.containers.GenericContainer.<init>(GenericContainer.java:245)
	...
Caused by: java.lang.NoSuchMethodException: org.testcontainers.images.AlwaysPullPolicy.<init>()
	at java.base/java.lang.Class.getConstructor0(Class.java:3761)
	at java.base/java.lang.Class.getConstructor(Class.java:2442)
	at org.testcontainers.images.PullPolicy.defaultPolicy(PullPolicy.java:43)
	... 8 more

Expected behavior

With this fix, the AlwaysPullPolicy can be configured directly in withImagePullPolicy(PullPolicy.alwaysPull()) and through the properties files.

Docs change

I would also propose a small change to the docs to contain an example that is functioning without users needing to provide their own implementation for testing purposes. I'm not sure though if this is something that fits the overall docs, so feel free to not include it.

[kiview]

That's a good one, thanks @sebastian-steiner and thanks for also updating the docs accordingly.

Will wait for @eddumelendez to have a look before merging.

[sebastian-steiner]

Thanks @kiview happy to hear that. :)
Is there anything to do for the two failing tests? It looks like they shouldn’t be connected to my changes.

[eddumelendez]

great catch! Thanks for your contribution, @sebastian-steiner !