Enable running jni test during gradle build

[navneet1v]

Description

Earlier the jni tests were not running as part of ./gradlew build, with this change the tests will run as part of ./gradlew build.

To enable the tests I added a new gradle task jniTest, which can be run via ./gradlew jniTest. I also added the dependency of check task of gradle on this test. As check already runs integTest and test so it make sense to run jni test as part of check.

check task is already a dependency of build task.

Also validated that on doing ./gradlew build --dry-run I can see jniTest task.

How to run jni test with gradle?

# To run all tests
./gradlew jniTest
# To run nmslib tests
./gradlew jniTest -Dgtest_filter=Nmslib*
# To run faiss tests
./gradlew jniTest -Dgtest_filter=Faiss*

Same is added in docs.

Why Jni Test is not added as part of test task?

The test task currently runs all the Java unit test. My initial plan was to do that only, but what it will lead to is if a user just want to run specific unit test via --tests, then also the jni test will run. We can add a parameter that can skip the tests if explicitly passed but this also creates a huddle as on failure of unit test we cannot just copy paste the command provided by gradle to run the failed unit test.

Issues Resolved

#1453

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed as per the DCO using --signoff

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