test: Add samples unit test

[AlexanderYastrebov]

This is just a fun excersise, the real validator should use shell script like in #82 since many implementations depend on different jdks and command line arguments.

For #61

[filiphr]

Cool idea @AlexanderYastrebov. An alternative for something like this might also be to use Dynamic Tests with a @TestFactory

The classes could be dynamically found. e.g. using CLassGraph

adding dependency

    <dependency>
      <groupId>io.github.classgraph</groupId>
      <artifactId>classgraph</artifactId>
      <version>4.8.165</version>
      <scope>test</scope>
    </dependency>

We can have a test that does something like:

    @TestFactory
    Stream<DynamicTest> testSamples() {
        String pkg = "dev.morling.onebrc";
        try (ScanResult scanResult =
                     new ClassGraph()
                             .enableClassInfo()
                             .acceptPackages(pkg)     // Scan com.xyz and subpackages (omit to scan all packages)
                             .scan()) {               // Start the scan
            return scanResult.getAllClasses()
                    .stream()
                    .filter(classInfo -> classInfo.getSimpleName().startsWith("CalculateAverage"))
                    .map(classInfo -> DynamicTest.dynamicTest(classInfo.getSimpleName(),
                            () -> TestSamples(TestCalculateAverage.class.getClassLoader().loadClass(classInfo.getName()))));
        }
    }

() -> TestSamples(TestCalculateAverage.class.getClassLoader().loadClass(classInfo.getName()))) is calling the test method that is already in there.

Side note, using something like a @TestFactory we could even lookup the calculate_average_<username>.sh files and invoke test.sh.

[gunnarmorling]

Do we still need this actually? Feel like the current shell test set-up is good enough for what we need?