JUnit und Testdesign

<?xml version="1.0" encoding="UTF-8"?>
        <project xmlns="http://maven.apache.org/POM/4.0.0"
                 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
            <modelVersion>4.0.0</modelVersion>
            <parent>
                <groupId>at.aydin.academy</groupId>
                <artifactId>19junittesting-pair</artifactId>
                <version>1.0.0</version>
                <relativePath>../pom.xml</relativePath>
            </parent>
            <artifactId>junit5-modern</artifactId>
            <packaging>jar</packaging>
            <name>JUnit 5 Modern</name>

            <dependencies>

<dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter</artifactId>
    <scope>test</scope>
</dependency>
<dependency><groupId>org.junit.jupiter</groupId><artifactId>junit-jupiter-params</artifactId><scope>test</scope></dependency>
            </dependencies>
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.apache.maven.plugins</groupId>
                        <artifactId>maven-compiler-plugin</artifactId>
                    </plugin>

                </plugins>
            </build>
        </project>

package at.aydin.lab.testing.modern;

// Design Pattern: Stateless Service – hält die Berechnung zustandsfrei und isoliert testbar.
public final class VatCalculator {
    public double gross(double net, double rate) {
        if (net < 0 || rate < 0) throw new IllegalArgumentException();
        return Math.round(net * (1 + rate) * 100.0) / 100.0;
    }
}

package at.aydin.lab.testing.modern;

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

// Design Pattern: Parameterized Test
// Zweck: Ein fachliches Verhalten wird mit mehreren repräsentativen Datenkombinationen geprüft.
class VatCalculatorTest {
    @ParameterizedTest
    @CsvSource({
        "100,0.2,120", "50,0.1,55", "0,0.2,0"
    }) void calculates(double net, double rate, double expected) {
        assertEquals(expected, new VatCalculator().gross(net, rate));
    }
}