RFR: 8255449: Improve the exception message of MethodHandles::permuteArguments [v3]

[Chris Hegarty]

On Wed, 28 Oct 2020 14:30:30 GMT, Chris Hegarty <chegar at openjdk.org> wrote:

>> I've added some negative tests that test for the different failure conditions.
>
> Thanks for adding additional test coverage @JornVernee.
> 
> Writing a tight implementation of assertThrows is non-trivial - I'm not sure that the version you have will fail if the exception is not thrown?  Either way maybe we can reuse some of the junit machinery for this purpose, e.g.:
> 
> static final Class<IllegalArgumentException> IAE = IllegalArgumentException.class;
> 
> public void testReorderTypeMismatch() throws Throwable {
>     MethodHandle mh = MethodHandles.empty(MethodType.methodType(void.class, int.class, int.class, String.class));
>     MethodType newType = MethodType.methodType(void.class, double.class, String.class);
>     var exception = expectThrows(IAE, () -> MethodHandles.permuteArguments(mh, newType, 0, 0, 1));
>     assertMatches(exception.getMessage(), ".*parameter types do not match after reorder.*");
> }
> 
> private static void assertMatches(String str, String pattern) {
>     if (!str.matches(pattern)) {
>         throw new AssertionError("'" + str + "' did not match the pattern '" + pattern + "'.");
>     }
> }

My last comment, that suggested to use expectThrows was not appropriate for this junit test ( I mistakenly assumed that that functional was available, but it is not ) - withdrawn.

Thanks for adding the extra check in assertThrows. LGTM.

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PR: https://git.openjdk.java.net/jdk/pull/878