test: migrate GetBinaryFilesTest to JUnit 5

[MartinWitt]

#3919

Change Log

The following bad smells are refactored:

JUnit4-@test

The JUnit 4 @Test annotation should be replaced with JUnit 5 @Test annotation.

JUnit4Assertion

The JUnit4 assertion should be replaced with JUnit5 Assertions.

The following has changed in the code:

JUnit4-@test

• Replaced junit 4 test annotation with junit 5 test annotation in testSingleBinary
• Replaced junit 4 test annotation with junit 5 test annotation in testExistingButNotBuiltBinary
• Replaced junit 4 test annotation with junit 5 test annotation in testMultiClassInSingleFile
• Replaced junit 4 test annotation with junit 5 test annotation in testNestedTypes
• Replaced junit 4 test annotation with junit 5 test annotation in testAnonymousClasses

JUnit4Assertion

• Transformed junit4 assert to junit 5 assertion in testSingleBinary
• Transformed junit4 assert to junit 5 assertion in testExistingButNotBuiltBinary
• Transformed junit4 assert to junit 5 assertion in testMultiClassInSingleFile
• Transformed junit4 assert to junit 5 assertion in testNestedTypes
• Transformed junit4 assert to junit 5 assertion in testAnonymousClasses

[slarse]

Weird annotation.

[slarse]

This looks strange?

[MartinWitt]

Sadly, JUnit 5 has no longer the @Rule annotations but extensions, see https://junit.org/junit5/docs/current/user-guide/#migrating-from-junit4-rule-support. The replacement for the old temporary folder concept is https://junit.org/junit5/docs/5.4.2/api/org/junit/jupiter/api/io/TempDir.html, https://www.baeldung.com/junit-5-temporary-directory.
Personally, I hate the new temporary folder concept and hope someone writes a clean extension for it.

[slarse]

Maybe I'm dense here, but where does @BeforeEach come into the picture?

I actuall quite like the new @TempDir construct, allows you to remove the field (ugh, fields!) and do something like this:

@Test
void testSomething(@TempDir workdir) {
    // use injected temporary directory
}

[MartinWitt]

Oh the @BeforeEach should be removed you are right

[MartinWitt]

I actuall quite like the new @tempdir construct, allows you to remove the field (ugh, fields!) and do something like this:

Yes, if you use this style it's nice, but then the whole codebase should do it this way and not mix of different styles

[slarse]

Yes, if you use this style it's nice, but then the whole codebase should do it this way and not mix of different styles

Good practices have to start somewhere :). That's kind of the thing with legacy, good practices have to be adopted gradually. And often, they are never fully adopted, but we can be watchful for future PRs.

If someone were to submit a PR with a JUnit5 test that had a field like this, I'd request a change. In this case, it's already there, so it's ok.