Some tests are incompatible with Rabbit 3.6 Java client

[wilkinsona]

Spring IO Platform 2.1 contains Spring AMQP 1.6 which requires version 3.6 of Rabbit's Java client. When Spring Cloud Connector's tests are run against the 3.6 client, two tests fail:

java.lang.AssertionError: expected:<0> but was:<60>
    at org.junit.Assert.fail(Assert.java:88)
    at org.junit.Assert.failNotEquals(Assert.java:834)
    at org.junit.Assert.assertEquals(Assert.java:118)
    at org.junit.Assert.assertEquals(Assert.java:144)
    at org.springframework.cloud.config.RabbitConnectionFactoryCloudConfigTestHelper.assertConfigProperties(RabbitConnectionFactoryCloudConfigTestHelper.java:26)
    at org.springframework.cloud.config.java.RabbitConnectionFactoryJavaConfigTest.cloudRabbitConnectionFactoryWithConfig(RabbitConnectionFactoryJavaConfigTest.java:41)

java.lang.AssertionError: expected:<0> but was:<60>
    at org.junit.Assert.fail(Assert.java:88)
    at org.junit.Assert.failNotEquals(Assert.java:834)
    at org.junit.Assert.assertEquals(Assert.java:118)
    at org.junit.Assert.assertEquals(Assert.java:144)
    at org.springframework.cloud.config.RabbitConnectionFactoryCloudConfigTestHelper.assertConfigProperties(RabbitConnectionFactoryCloudConfigTestHelper.java:26)
    at org.springframework.cloud.config.xml.RabbitConnectionFactoryXmlConfigTest.cloudRabbitConnectionFactoryWithConfiguration(RabbitConnectionFactoryXmlConfigTest.java:39)

You can reproduce the two failures by running the following build:

./gradlew clean springIoCheck -PJDK8_HOME=<path-to-jdk8-home> -PplatformVersion=2.1.0.BUILD-SNAPSHOT --continue

Unfortunately, this can't be fixed by just changing the Rabbit client dependency and updating the tests accordingly in 1.2.x. As things stand Spring Cloud Connectors 1.2.x is part of Spring IO Platform 2.0 (which uses Rabbit Client 3.4.x) and not-yet-released Spring IO Platform 2.1 which uses 3.6.x. This means that 1.2.x's tests need to pass when run against both versions of the client.

A few ideas:

1. Create a new minor release of Spring Cloud Connectors that uses Rabbit Client 3.6.x. This seems excessive if there are no other changes to warrant the new minor release.
2. Update the tests so that they no longer assert the client's defaults and just assert on the pieces of configuration that Spring Cloud Connectors has set.
3. Update the tests so that they accept either the old default or the new default

[garyrussell]

Spring AMQP 1.6 which requires version 3.6

Just one point of clarification; 1.6 does not require 3.6, it just pulls it in by default; it's actually backwards-compatible to 3.4.

Not pertinent to this discussion of course but I also noticed that the connector is still using an ancient client (2.8.1) by default.

#155

[wilkinsona]

Thanks, Gary. I was a little sloppy. A more accurate statement would have been that Spring AMQP 1.6's tests require 3.6.

[scottfrederick]

Thanks @wilkinsona and @garyrussell. Gary's PR looks good, and has been merged.

Not pertinent to this discussion of course but I also noticed that the connector is still using an ancient client (2.8.1) by default.

Connectors generally relies on the oldest versions of Spring and connection dependencies that are API-compatible with the things it needs to do. This helps ensure that Connectors is compatible with as many client apps as possible. Connectors has only optional dependencies on other Spring and connection libraries (as it expects the client app to bring its own versions of just the dependencies it needs) so none of these dependencies is transitive.