add simple mocking demo

MvnDemo/pom.xml

@@ -27,6 +27,13 @@
 			<scope>test</scope>
 		</dependency>
 
+		<dependency>
+			<groupId>org.mockito</groupId>
+			<artifactId>mockito-core</artifactId>
+			<version>5.17.0</version>
+			<scope>test</scope>
+		</dependency>
+
 		<dependency>
 			<groupId>org.apache.logging.log4j</groupId>
 			<artifactId>log4j-core</artifactId>
@@ -66,7 +73,8 @@
 							<transformers>
 								<transformer
 									implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
-									<mainClass>de.hs_mannheim.informatik.mvn.Main</mainClass>
+									<mainClass>
+										de.hs_mannheim.informatik.mvn.Main</mainClass>
 								</transformer>
 							</transformers>
 						</configuration>
@@ -120,7 +128,8 @@
 
 	<reporting>
 		<plugins>
-			<!-- generate Javadocs via "mvn site" and find them in the site folder-->
+			<!-- generate Javadocs via "mvn site" and find them in the site
+			folder-->
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-javadoc-plugin</artifactId>

MvnDemo/src/main/java/de/hs_mannheim/informatik/mvn/mocking/CountWords.java

@@ -0,0 +1,28 @@
+package de.hs_mannheim.informatik.mvn.mocking;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class CountWords {
+
+	public static void main(String[] args) {
+		var cnt = new CountWords().countWords("Der schnelle braune Fuchs springt über den mueden Hund. Der Hund liegt nur muede herum.");
+		cnt.entrySet().stream().forEach(e -> System.out.println(e.getKey() + ": " + e.getValue()));
+	}
+	
+	public Map<String, Integer> countWords(String text) {
+		var words = text.toLowerCase().split("\\W+");
+		var cnt = new HashMap<String, Integer>();
+		
+		for (String w : words) {
+			cnt.put(w, cnt.getOrDefault(w, 0) + 1);
+		}
+		
+		return cnt;
+	}
+	
+	public Map<String, Integer> countWordsFromFile(TextExtractor te, String path) {
+		return this.countWords(te.extractText(path));
+	}
+
+}

MvnDemo/src/main/java/de/hs_mannheim/informatik/mvn/mocking/TextExtractor.java

@@ -0,0 +1,5 @@
+package de.hs_mannheim.informatik.mvn.mocking;
+
+public abstract class TextExtractor {	
+	public abstract String extractText(String path);
+}

MvnDemo/src/test/java/de/hs_mannheim/informatik/mvn/mocking/TextExtractorTest.java

@@ -0,0 +1,37 @@
+package de.hs_mannheim.informatik.mvn.mocking;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+class TextExtractorTest {
+
+	@Test
+	void testCountWords() {
+		CountWords cw = new CountWords();
+		var cnt = cw.countWords("hallo welt");
+		
+		assertEquals(1, cnt.get("hallo"));
+		assertEquals(1, cnt.get("welt"));
+		
+		assertEquals(null, cnt.get("unbekannt"));
+	}
+	
+	@Test
+	void testCountWordsFromFile() {
+		CountWords cw = new CountWords();
+		
+		TextExtractor teMock = Mockito.mock(TextExtractor.class);
+		when(teMock.extractText("/tmp/test.pdf")).thenReturn("hallo welt");
+		
+		var cnt = cw.countWordsFromFile(teMock, "/tmp/test.pdf");
+		
+		assertEquals(1, cnt.get("hallo"));
+		assertEquals(1, cnt.get("welt"));
+		
+		assertEquals(null, cnt.get("unbekannt"));
+	}
+
+}