RFR(L): 8229186: Improve error messages for TestStringIntrinsics failures

[Evgeny Nikitin]

Forwarding to the compiler mailing list as this changes a test in the 
Compiler area.

On 2020-05-18 16:46, Evgeny Nikitin wrote:
> Hi,
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8229186
> Webrev: http://cr.openjdk.java.net/~enikitin/8229186/webrev.00/
> 
> Error reporting was improved by writing a C-style escaped string 
> representations for the variables passed to the methods being tested. 
> For array comparisons, a dedicated diff-formatter was implemented.
> 
> Sample output for comparing byte arrays (with artificial failure):
> ----------System.err:(21/1553)----------
> Result: (false) of 'arrayEqualsB' is not equal to expected (true)
> Arrays differ starting from [index: 7]:
> ... 5, 6,   7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 
> 23, ...
> ... 5, 6, 125, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 
> 23, ...
>           ^^^^
> java.lang.RuntimeException: Result: (false) of 'arrayEqualsB' is not 
> equal to expected (true)
>          at 
> compiler.intrinsics.string.TestStringIntrinsics.invokeAndCheckArrays(TestStringIntrinsics.java:273) 
> 
>          at ... stack trace continues - E.N.
> 
> Sample output for comparing char arrays:
> ----------System.err:(21/1579)*----------
> Result: (false) of 'arrayEqualsC' is not equal to expected (true)
> Arrays differ starting from [index: 7]:
> ... \\u0005, \\u0006, \\u0007, \\u0008, \\u0009, \\n, \\u000B, \\u000C, 
> \\r, \\u000E, ...
> ... \\u0005, \\u0006,      }, \\u0008, \\u0009, \\n, \\u000B, \\u000C, 
> \\r, \\u000E, ...
>                     ^^^^^^^
> java.lang.RuntimeException: Result: (false) of 'arrayEqualsC' is not 
> equal to expected (true)
>          at 
> compiler.intrinsics.string.TestStringIntrinsics.invokeAndCheckArrays(TestStringIntrinsics.java:280) 
> 
>          at
> ... and so on - E.N.
> 
> Please review.
> Thanks in advance,
> /Evgeny Nikitin.