GEODE-5960: Add test to verify CommandMarker file for the JDBC connector

[BenjaminPerryRoss]

Added a new test to the JDBC connector project to verify that the list
of commands loaded via the scanner and the command marker match the list
of commands found via these two sources. This is to avoid
errors/warnings due to commands which appear in Command Marker files but
don't have available source code.

Co-authored-by: Ben Ross bross@pivotal.io
Co-authored-by: Darrel Schneider dschneider@pivotal.io

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[sboorlagadda]

CommandAvailabilityIndicatorTest is kind of providing some coverage to assert that commands are available online. But this test seems to be a more basic test to help developers to figure out if he misses the markers.

[jinmeiliao]

I am not sure what this test is for. the commandManager actually uses the package scanner to scan the classpath to compose its list of commands, so the test is just reiterates what the commandManager is doing. So if a command did not implement CommandMarker, this test would still pass, I believe.

[jinmeiliao]

A better test is probably to write an acceptance test for each jdbc gfsh commands.

[dschneider-pivotal]

Jinmei, this test is only to catch when we remove a command class that still has its name in the CommandMarker file. With what is currently checked in, all the open side tests pass even though a user of gfsh will get a warning about that command class not existing.
We have verified that this new test fails if the CommandMarker file contains a class name that does not exist. And that is all this test attempting to verify.

[jinmeiliao]

@dschneider-pivotal now I see that this test is to make sure all commands defined in the commandMarker file is able to load, then you don't need to scan the packages to get a list of all the commands at all, you can just get the list of commands loaded by service loader and make sure they exists in the command manager, this can make your test a lot shorter. Something like this:

ServiceLoader loader =
ServiceLoader.load(CommandMarker.class, ClassPathLoader.getLatest().asClassLoader());
loader.reload();
Iterator iterator = loader.iterator();

List<Class>
    allCommandClass = commandManager.getCommandMarkers().stream().map(CommandMarker::getClass).collect(
    Collectors.toList());
while (iterator.hasNext()) {
  Class<? extends CommandMarker> commandClass = iterator.next().getClass();
  assertThat(allCommandClass).contains(commandClass);
}