Testing And Benchmarking in Fortress

Here’s the translation of the Go testing and benchmarking example to Java, formatted in Markdown suitable for Hugo:

Unit testing is an important part of writing principled Java programs. The JUnit framework provides the tools we need to write unit tests, and we can use build tools like Maven or Gradle to run tests.

For the sake of demonstration, this code is in a single file, but it could be split into separate files. Testing code typically lives in a separate directory from the main code, often under a src/test/java directory.

import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.CsvSource;
import static org.junit.jupiter.api.Assertions.*;

public class IntUtilsTest {

    // We'll be testing this simple implementation of an integer minimum.
    public static int intMin(int a, int b) {
        return a < b ? a : b;
    }

    // A test is created by writing a method with @Test annotation.
    @Test
    public void testIntMinBasic() {
        int ans = intMin(2, -2);
        // assertEquals will report test failures
        assertEquals(-2, ans, "IntMin(2, -2) should be -2");
    }

    // Writing tests can be repetitive, so it's idiomatic to use
    // parameterized tests, where test inputs and expected outputs
    // are provided as parameters.
    @ParameterizedTest
    @CsvSource({
        "0, 1, 0",
        "1, 0, 0",
        "2, -2, -2",
        "0, -1, -1",
        "-1, 0, -1"
    })
    public void testIntMinParameterized(int a, int b, int expected) {
        int ans = intMin(a, b);
        assertEquals(expected, ans, 
            String.format("IntMin(%d, %d) should be %d", a, b, expected));
    }
}

For benchmarking in Java, we typically use frameworks like JMH (Java Microbenchmark Harness). Here’s a simple example:

import org.openjdk.jmh.annotations.*;
import java.util.concurrent.TimeUnit;

@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Thread)
public class IntUtilsBenchmark {

    @Benchmark
    public void benchmarkIntMin() {
        IntUtilsTest.intMin(1, 2);
    }
}

To run the tests, you would typically use a build tool like Maven or Gradle. With Maven, you might run:

$ mvn test

This would output something like:

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running IntUtilsTest
Tests run: 6, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.068 s

To run benchmarks with JMH, you would typically set up your project to use the JMH plugin, then run:

$ mvn clean install
$ java -jar target/benchmarks.jar

This would output detailed benchmark results, including operations per second and average time per operation.

In Java, the process of running tests and benchmarks is typically more involved than in some other languages, often requiring the use of build tools and additional setup. However, this approach provides a lot of flexibility and power for complex projects.

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