Migrate win32 unit tests to JUnit 5 and reduce test visibility #1298

[HeikoKlare]

This migrates the unit tests placed in the SWT win32 production fragments to JUnit 5. The visibility of the test classes is reduced to packaged protected as allowed by JUnit 5.

This resolves the API errors as reported in #1298.

Fixes #1298

[github-actions]

Test Results

   470 files  ±0     470 suites  ±0   7m 59s ⏱️ - 1m 10s
 4 135 tests ±0   4 127 ✅ ±0   8 💤 ±0  0 ❌ ±0 
16 336 runs  ±0  16 244 ✅ ±0  92 💤 ±0  0 ❌ ±0 

Results for commit 36cab26. ± Comparison against base commit f40502d.

[vogella]

LGTM

[HeikoKlare]

Tests are still properly executed, even with reduced test class visibility after JUnit 5 migration:

[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.422 s -- in org.eclipse.swt.graphics.GCWin32Tests
[INFO] Running org.eclipse.swt.graphics.PathWin32Tests
[INFO] Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.031 s -- in org.eclipse.swt.graphics.PathWin32Tests
[INFO] Running org.eclipse.swt.graphics.TextLayoutWin32Tests
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.031 s -- in org.eclipse.swt.graphics.TextLayoutWin32Tests
[INFO] Running org.eclipse.swt.graphics.TransformWin32Tests
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.015 s -- in org.eclipse.swt.graphics.TransformWin32Tests
[INFO] Running org.eclipse.swt.internal.DefaultSWTFontRegistryTests
[INFO] Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.016 s -- in org.eclipse.swt.internal.DefaultSWTFontRegistryTests
[INFO] Running org.eclipse.swt.internal.ScalingSWTFontRegistryTests
[INFO] Tests run: 5, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.015 s -- in org.eclipse.swt.internal.ScalingSWTFontRegistryTests
[INFO] Running org.eclipse.swt.widgets.ControlWin32Tests
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.016 s -- in org.eclipse.swt.widgets.ControlWin32Tests
[INFO] Running org.eclipse.swt.widgets.WidgetWin32Tests
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.078 s -- in org.eclipse.swt.widgets.WidgetWin32Tests

[HeikoKlare]

@merks are you fine with merging this as it subsumes your proposal #1303?

[merks]

@HeikoKlare

Of course that's fine. I only created the other PR because I already had it in my workspace for testing the effect.