Testing And Benchmarking in CLIPS

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. JUnit is a popular testing framework for Java that provides the tools we need to write unit 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 test class file.

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.*;

class IntUtils {
    // 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
    void testIntMinBasic() {
        int ans = IntUtils.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 to a single test method.
    @ParameterizedTest
    @CsvSource({
        "0, 1, 0",
        "1, 0, 0",
        "2, -2, -2",
        "0, -1, -1",
        "-1, 0, -1"
    })
    void testIntMinParameterized(int a, int b, int expected) {
        int ans = IntUtils.intMin(a, b);
        assertEquals(expected, ans, 
            String.format("IntMin(%d, %d) should be %d", a, b, expected));
    }
}

For benchmarking in Java, we typically use a dedicated benchmarking framework like JMH (Java Microbenchmark Harness). Here’s a simple example of how you might set up a benchmark:

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() {
        IntUtils.intMin(1, 2);
    }

    // To run the benchmark, you would typically use the JMH runner
    public static void main(String[] args) throws Exception {
        org.openjdk.jmh.Main.main(args);
    }
}

To run the tests, you would typically use a build tool like Maven or Gradle, or you could run them directly from your IDE. Here’s an example of what the output might look like when running tests:

JUnit Jupiter > IntUtilsTest > testIntMinBasic() PASSED
JUnit Jupiter > IntUtilsTest > testIntMinParameterized(int, int, int) PASSED
    [1] 0, 1, 0
    [2] 1, 0, 0
    [3] 2, -2, -2
    [4] 0, -1, -1
    [5] -1, 0, -1

Test run finished after 123 ms
[         3 containers found      ]
[         0 containers skipped    ]
[         3 containers started    ]
[         0 containers aborted    ]
[         3 containers successful ]
[         0 containers failed     ]
[         6 tests found           ]
[         0 tests skipped         ]
[         6 tests started         ]
[         0 tests aborted         ]
[         6 tests successful      ]
[         0 tests failed          ]

For benchmarks, the output would depend on your specific JMH configuration, but it might look something like this:

Benchmark                        Mode  Cnt   Score   Error  Units
IntUtilsBenchmark.benchmarkIntMin  avgt    5   2.275 ± 0.083  ns/op

This indicates that the intMin method took an average of about 2.275 nanoseconds per operation.

Remember to always use appropriate benchmarking techniques and interpret results carefully, as micro-benchmarks can be misleading due to factors like JIT compilation and garbage collection.

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Testing And Benchmarking in CLIPS