Support for non-public @Parameter

[vorburger]

Hello JUnit!

This patch makes it possible to have @parameter fields in @RunWith(Parameterized.class) tests non-public.

I'm not sure if my change to ParameterizedTestTest is really an appropriate and sufficient test for this minor extension. (But the patch does work and achieve what it should, of course.)

BTW: As I've also found that @parameter was not yet documented on https://github.com/junit-team/junit/wiki/Parameterized-tests, I've taken the liberty of going ahead and directly adding a section about it (incl. ref. to this) - hope that's OK.

Regards,
Michael

[kcooney]

Thanks for the contribution

Field.setAccessible(true) can fail if a security manager is installed, which can be the case in some environments, so JUnit requires fields and methods that need to be accessed reflectively to be public.

[dsaff]

@kcooney's explanation is correct.

[DirkyJerky]

Couldnt you just check the Security manager check before hand, mark a flag, and if the flag is marked skip the Field.setAccessible(true) call?

Going to make a PR

[geertschuring]

Hey guys, im still getting the following exception when running a parameterized test with @parameter on private members:

java.lang.IllegalAccessException: Cannot set parameter 'expectedOutputFile'. Ensure that the field 'expectedOutputFile' is public.
	at org.junit.runners.parameterized.BlockJUnit4ClassRunnerWithParameters.createTestUsingFieldInjection(BlockJUnit4ClassRunnerWithParameters.java:77)
	at org.junit.runners.parameterized.BlockJUnit4ClassRunnerWithParameters.createTest(BlockJUnit4ClassRunnerWithParameters.java:48)
	at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:260)
	at org.junit.runners.BlockJUnit4ClassRunner$2.runReflectiveCall(BlockJUnit4ClassRunner.java:309)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:306)
	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
	at org.junit.runners.Suite.runChild(Suite.java:128)
	at org.junit.runners.Suite.runChild(Suite.java:27)
	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:89)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:41)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:542)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:770)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:464)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:210)
Caused by: java.lang.IllegalAccessException: Class org.junit.runners.parameterized.BlockJUnit4ClassRunnerWithParameters can not access a member of class MessageConverterParameterizedTest with modifiers "private"
	at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:102)
	at java.lang.reflect.AccessibleObject.slowCheckMemberAccess(AccessibleObject.java:296)
	at java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:288)
	at java.lang.reflect.Field.set(Field.java:761)
	at org.junit.runners.parameterized.BlockJUnit4ClassRunnerWithParameters.createTestUsingFieldInjection(BlockJUnit4ClassRunnerWithParameters.java:75)
	... 30 more

Did this PR not get merged somehow?

[marcphilipp]

No, it was rejected with the rationale explained in #737 (comment).