Update TESTING.asciidoc for recent REST test changes (#62841)

* Remove reference to Runner (no longer valid)
* Remove tests.rest (no longer valid)
* Add reference to javaRestTest
* Brief mention of qa tests

TESTING.asciidoc

@@ -308,20 +308,19 @@ The REST tests are run automatically when executing the "./gradlew check" comman
 YAML REST tests use the following command (modules and plugins may also include YAML REST tests):
 
 ---------------------------------------------------------------------------
-./gradlew :rest-api-spec:yamlRestTest
+./gradlew :rest-api-spec:yamlRestTest 
 ---------------------------------------------------------------------------
 
 A specific test case can be run with the following command:
 
 ---------------------------------------------------------------------------
-./gradlew ':rest-api-spec:yamlRestTestRunner' \
+./gradlew ':rest-api-spec:yamlRestTest' \
   --tests "org.elasticsearch.test.rest.ClientYamlTestSuiteIT" \
-  -Dtests.method="test {p0=cat.segments/10_basic/Help}"
+  -Dtests.method="test {p0=cat.segments/10_basic/Help}" 
 ---------------------------------------------------------------------------
 
-The REST tests support all the options provided by the randomized runner, plus the following:
+The YAML REST tests support all the options provided by the randomized runner, plus the following:
 
-* `tests.rest[true|false]`: determines whether the REST tests need to be run (default) or not.
 * `tests.rest.suite`: comma separated paths of the test suites to be run
 (by default loaded from /rest-api-spec/test). It is possible to run only a subset
 of the tests providing a sub-folder or even a single yaml file (the default
@@ -331,6 +330,27 @@ e.g. -Dtests.rest.suite=index,get,create/10_with_id
 blacklisted and need to be skipped
 e.g. -Dtests.rest.blacklist=index/*/Index document,get/10_basic/*
 
+Java REST tests can be run with the "javaRestTest" task.
+
+For example :
+---------------------------------------------------------------------------
+./gradlew :modules:mapper-extras:javaRestTest 
+---------------------------------------------------------------------------
+
+A specific test case can be run with the following syntax (fqn.test {params}):
+
+---------------------------------------------------------------------------
+./gradlew ':modules:mapper-extras:javaRestTest' \
+  --tests "org.elasticsearch.index.mapper.TokenCountFieldMapperIntegrationIT.testSearchByTokenCount {storeCountedFields=true loadCountedFields=false}" 
+---------------------------------------------------------------------------
+
+yamlRestTest's and javaRestTest's are easy to identify, since they are found in a
+respective source directory. However, there are some more specialized REST tests
+that use custom task names. These are usually found in "qa" projects commonly
+use the "integTest" task.
+
+If in doubt about which command to use, simply run <gradle path>:check
+
 == Testing packaging
 
 The packaging tests use Vagrant virtual machines or cloud instances to verify