This commit introduces `CodecCustomizer`, a new callback-based interface
for customizing the codecs configuration for WebFlux server and client.
Instances of those customizers are applied to the `WebClient.Builder`
and to the `WebFluxAutoConfiguration` (which deals with both WebFlux and
WebFlux.fn).
For now, only Jackson codecs are auto-configured, by getting the
`ObjectMapper` instance created by Spring Boot. Other codecs can be
configured as soon as WebFlux supports those.
Closes gh-9166
This commit adds a new customizer interface for applying
configuration changes to `WebClient.Builder` beans:
`WebClientCustomizer`.
The new WebClient auto-configuration will make available, as a
prototype scoped bean, `WebClient.Builder` instances.
Once injected, developers can use those to create `WebClient`
instances to be used in their application.
`WebClientCustomizer` beans are sorted according to their
`Order` and then applied to the builder instances.
Closes gh-9522
This commit adds ContextLoader, a test helper that configures an
ApplicationContext that is meant to simulate a particular
auto-configuration scenario.
The auto-configuration, user configuration and environment can be
customized. The loader invokes a ContextConsumer to assert the context
and automatically close the context once it is done.
Concretely, tests can create a shared field instance of that helper with
the shared configuration to increase its visibility and tune the context
further in each test.
If the context is expected to fail, `loadAndFail` allows to optionally
assert the root exception and consume it for further assertions.
This commit also migrates some tests to illustrate the practical use of
the helper
Closes gh-9634