RFR: 8255561: add tests to check binary compatibility rules for records

[Jonathan Gibbons]

On Thu, 5 Nov 2020 18:55:12 GMT, Vicente Romero <vromero at openjdk.org> wrote:

> Hi all,
> 
> Please review this change. It is providing compatibility tests for records. The tests are covering the assertions at section: [13.4.27 Evolution of Record Classes](http://cr.openjdk.java.net/~gbierman/8246771/8246771-20200928/specs/records-jls.html#jls-13.4.27).
> 
> Thanks,
> Vicente

A coupe of suggestions, one more significant that the other

test/langtools/tools/javac/records/RecordsBinaryCompatibilityTests.java line 277:

> 275: 
> 276:         // let's first check that it runs wo issues
> 277:         if (!output.contains("0")) {

This is a very weak test that may easily fail for the wrong reasons.  Can you make the reference value more distinctive, like 12345, or "Hello World" that could never appear accidentally

test/langtools/tools/javac/records/RecordsBinaryCompatibilityTests.java line 251:

> 249:             String clientCode,
> 250:             boolean shouldFail,
> 251:             String expectedError) throws Exception {

Since the expected error always seems to be the name of a class, you could make the type of the parameter be `Class<?>` and then pass class literals as arguments. Inside the method, you get use `getName()` to get the name you expect to see.

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PR: https://git.openjdk.java.net/jdk/pull/1082