RFR: 8254013: gradle test should run all test classes even if they don't end with "Test"

[Kevin Rushforth]

The test targets in `build.gradle` are set up to run only classes whose name ends with exactly `Test`. A test class named `RunMyTest.java` will be run, but a test called `CheckSomething.java` will not be. This was done because gradle's built-in scanner for test classes was buggy in earlier versions of gradle. It seems to have been fixed in the gradle 3.x time frame from what I can tell.

The current approach leads to two problems. The first is that gradle will try to execute  all classes named `XxxxxTest.java` whether or not it should. Attempting to execute utility classes without test methods (meaning without at least one method annotated with `@Test`) or `abstract` classes (whether or not there are any test methods) will fail.

The second is that a test class that isn't named `XxxxxTest.java` will not be run, even if it contains `@Test` methods. This can (and has) lead to tests being skipped when they should be run.

The solution is to enable gradle's built-in scanning for test classes which works exactly like you would expect it to: it runs any concrete class that has at least one `@Test` method or whose parent class has such a method. This means that a class with no test methods that subclasses an abstract class with `@Test` methods will be run correctly.

I ran a full test on all three platforms. The following test classes which were formerly not run are now run:

modules/javafx.base: test.javafx.collections.ObservableListWithExtractor : 52 tests
modules/javafx.base: test.javafx.event.EventSerializationEventExists 0 tests (*)
modules/javafx.controls:. test.javafx.scene.control.MiscellaneousTests : 3 tests
tests/system: test.com.sun.javafx.application.SwingNoExit : 1 test

They pass on all three platforms.

(*) - There is only one test in this class and it is currently `@Ignore`d

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Commit messages:
 - 8254013: gradle test should run all test classes even if they don't end with "Test"

Changes: https://git.openjdk.java.net/jfx/pull/329/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=329&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254013
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jfx/pull/329.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/329/head:pull/329

PR: https://git.openjdk.java.net/jfx/pull/329