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- Lecture on Thursday, 5th, 2026.
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‎2026-02-05-Retro_Copilot/README.md‎

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# Retrospective, Evaluation, with a grain of AI
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## Retrospective, Evaluation
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* [Use Evaluation Link](https://lehreval.psy.uni-osnabrueck.de/evasys/online.php?pswd=PHACT)
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* Or scan QR code below:<br><img src="src/main/resources/QRCode_PHACT.png" width="400"/>
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## Feedback

‎2026-02-05-Retro_Copilot/pom.xml‎

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<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<version>1.0.0-SNAPSHOT</version>
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<groupId>de.hilling.intro-to-coding</groupId>
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<artifactId>samples</artifactId>
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</parent>
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<artifactId>retro-copilot</artifactId>
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<name>Retrospective, Evaluation, with a grain of AI</name>
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<dependencies>
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<dependency>
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<groupId>org.jspecify</groupId>
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<artifactId>jspecify</artifactId>
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</dependency>
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</dependencies>
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</project>

‎2026-02-05-Retro_Copilot/src/main/java/de/hilling/chess/Position.java‎

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package de.hilling.chess;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.regex.Pattern;
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import org.jspecify.annotations.NonNull;
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/**
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* Represents a position on the board.
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* Objects of this class are immutable, correct coordinates are checked when the constructor is called.
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*/
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public class Position extends Object {
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private static final char[] X_CHARACTERS = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'};
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private static final Map<String, Position> VALID_POSITIONS = new HashMap<>();
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public final int x;
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public final int y;
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public final String formattedPosition;
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static {
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for (int x = 0; x < 8; x++) {
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for (int y = 0; y < 8; y++) {
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Position position = new Position(x, y);
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VALID_POSITIONS.put(position.formattedPosition, position);
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}
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}
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}
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private Position(int x, int y) {
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validatePosition(x, y);
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this.x = x;
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this.y = y;
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formattedPosition = String.format("%c%d", X_CHARACTERS[x], y + 1);
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}
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private static void validatePosition(int x, int y) {
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if (x < 0 || y < 0 || x > 7 || y > 7) {
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throw new IllegalArgumentException("x and y need to be between 0 and 7");
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}
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}
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/**
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* Access Position object via position string (chess notation).
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*
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* @param positionString position between "a1 and h8".
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* @return Position element
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* @throws IllegalArgumentException if positionString is invalid.
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*/
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public static @NonNull Position of(@NonNull String positionString) {
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Position position = VALID_POSITIONS.get(positionString);
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if (position == null) {
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throw new IllegalArgumentException("Illegal position: " + positionString);
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}
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return position;
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}
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/**
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* Access Position object via offset.
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*
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* @param x x-offset, starting at 0.
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* @param y y-offset, starting at 0
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* @return Position element
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* @throws IllegalArgumentException if x or y are not between 0 and 7.
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*/
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public static @NonNull Position of(int x, int y) {
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validatePosition(x, y);
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return of(String.format("%c%d", X_CHARACTERS[x], y + 1));
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}
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@Override
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public String toString() {
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return formattedPosition;
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}
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}

‎2026-02-05-Retro_Copilot/src/main/java/de/hilling/chess/Sort.java‎

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package de.hilling.chess;
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import java.util.List;
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import org.jspecify.annotations.NonNull;
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/**
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* Provide the static {@link Sort#sort(List)} function.
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*/
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public class Sort {
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private static boolean debug;
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// Never instantiated.
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private Sort() {}
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public static void setDebug(boolean debug) {
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Sort.debug = debug;
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}
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/**
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* Sort the given List inplace.
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*
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* @param elements comparable non-null Objects.
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* @param <T> Type implementing {@link Comparable}.
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* @return
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*
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*/
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public static @NonNull <T extends Comparable<T>> List<@NonNull T> sort(@NonNull List<@NonNull T> elements) {
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print(elements);
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quickSort(elements, 0, elements.size() -1);
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return elements;
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}
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private static <T extends Comparable<T>> void quickSort(@NonNull List<@NonNull T> elements, int left, int right) {
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if(unsorted(elements, left, right)) {
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print("quicksort: " + (left+1) + ", " + (right+1));
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int partitionIndex = partition(elements, left, right);
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quickSort(elements, left, partitionIndex - 1);
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quickSort(elements, partitionIndex + 1, right);
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}
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}
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private static <T extends Comparable<T>> boolean unsorted(@NonNull List<T> elements, int left, int right) {
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if(left >= right) {
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return false;
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}
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for(int index = left; index <= right; index++) {
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if(elements.get(index).compareTo(elements.get(right)) > 0) {
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return true;
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}
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}
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return false;
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}
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private static <T extends Comparable<T>> int partition(@NonNull List<@NonNull T> elements, int left, int right) {
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T pivot = elements.get(right);
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print("piv " + pivot + " " + elements);
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int i = (left - 1);
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for (int j = left; j < right; j++) {
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if(elements.get(j).compareTo(pivot) <= 0) {
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i++;
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swap(elements, i, j);
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}
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}
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print("move pivot element to " + (i + 1));
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swap(elements, i + 1, right);
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return i + 1;
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}
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private static <T extends Comparable<T>> void swap(@NonNull List<T> elements, int i, int j) {
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T temp = elements.get(i);
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elements.set(i, elements.get(j));
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elements.set(j, temp);
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print((i+1) + "<->" + (j+1) + " " + elements);
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}
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private static void print(Object output) {
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if(debug) {
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System.out.println(output);
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}
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}
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}

‎2026-02-05-Retro_Copilot/src/main/resources/QRCode_PHACT.png‎

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‎2026-02-05-Retro_Copilot/src/test/java/de/hilling/chess/PositionGenericsTest.java‎

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package de.hilling.chess;
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import static org.junit.jupiter.api.Assertions.*;
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import java.util.Arrays;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.List;
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import org.junit.jupiter.api.BeforeEach;
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import org.junit.jupiter.api.Test;
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class PositionGenericsTest {
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static final Position A1 = Position.of("a1");
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static final Position A2 = Position.of("a2");
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static final Position B1 = Position.of("b1");
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static final Position B2 = Position.of("b2");
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List<Position> positionList;
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List<Position> randomPositionList;
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Collection<Position> randomCollection;
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List<Integer> sortedIntegerList;
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List<Integer> unsortedIntegerList;
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@BeforeEach
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void setUp() {
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positionList = Arrays.asList(A1, A2, B1, B2);
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randomPositionList = Arrays.asList(A2, B1, A1, B2, A1);
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randomCollection = Arrays.asList(A1, B1, A2, B2);
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sortedIntegerList = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
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unsortedIntegerList = Arrays.asList(4, 7, 9, 10, 5, 3, 1, 2, 8, 6);
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}
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@Test
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void compareDifferentPositions() {
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Collection<Position> positions = randomPositionList;
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List bareList = randomPositionList;
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List<Object> objectList = bareList;
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// List<Object> objectList = randomPositionList;
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}
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@Test
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void sortIntegerList() {
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Collections.sort(unsortedIntegerList);
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assertEquals(1, unsortedIntegerList.getFirst());
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assertEquals(sortedIntegerList, unsortedIntegerList);
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}
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}

‎2026-02-05-Retro_Copilot/src/test/java/de/hilling/chess/PositionTest.java‎

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package de.hilling.chess;
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import org.junit.jupiter.api.Test;
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import static org.junit.jupiter.api.Assertions.*;
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class PositionTest {
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@Test
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void setUpValidPositions() {
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assertEquals("a1", Position.of(0, 0).toString());
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assertEquals("e5", Position.of(4, 4).toString());
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assertEquals("h8", Position.of(7, 7).toString());
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}
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@Test
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void compareDifferentPositions() {
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Position p1 = Position.of(0, 0);
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Position p2 = Position.of(1, 0);
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assertNotEquals(p1, p2);
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}
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@Test
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void compareEqualPositions() {
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Position p1 = Position.of(0, 0);
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Position p2 = Position.of(0, 0);
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assertEquals(p1, p2);
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}
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@Test
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void compareDifferentPositionHash() {
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assertNotEquals(Position.of(0, 1).hashCode(), Position.of(0, 0).hashCode());
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}
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@Test
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void accessPositionObject() {
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Position positionA = Position.of("a1");
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assertSame(positionA, Position.of("a1"));
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}
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@Test
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void denyNegativePositions() {
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try {
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Position.of(-1, 0);
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fail("IllegalArgumentException expected");
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} catch (IllegalArgumentException ile) {
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// success
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}
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}
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@Test
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void denyOverflowPositions() {
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try {
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Position.of(0, 8);
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fail("IllegalArgumentException expected");
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} catch (IllegalArgumentException ile) {
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// success
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}
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}
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@Test
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void denyIllegalStringPositions() {
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try {
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Position.of("a9");
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fail("IllegalArgumentException expected");
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} catch (IllegalArgumentException ile) {
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// success
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}
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}
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}

‎2026-02-05-Retro_Copilot/src/test/java/de/hilling/chess/SortTest.java‎

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package de.hilling.chess;
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import static org.junit.jupiter.api.Assertions.*;
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import java.util.Arrays;
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import java.util.List;
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import org.junit.jupiter.api.BeforeEach;
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import org.junit.jupiter.api.Test;
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class SortTest {
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List<Integer> sortedIntegerList;
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List<Integer> unsortedIntegerList;
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@BeforeEach
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void setUp() {
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Sort.setDebug(true);
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sortedIntegerList = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
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unsortedIntegerList = Arrays.asList(4, 7, 9, 10, 5, 3, 1, 2, 8, 6);
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}
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@Test
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void compareDifferentPositionsSort() {
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assertEquals(sortedIntegerList, Sort.sort(unsortedIntegerList));
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}
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}

‎pom.xml‎

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<module>2026-01-16-CommonPropertiesOfAnObject</module>
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<module>2026-01-23-Private_Constructors</module>
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<module>2026-01-30-Generics_Sorting</module>
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<module>2026-02-05-Retro_Copilot</module>
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</modules>
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<properties>

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