Add tests.

src/test/java/de/tudresden/inf/mci/brailleplot/configparser/JavaPropertiesConfigurationParserTest.java

+package de.tudresden.inf.mci.brailleplot.configparser;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.NoSuchElementException;
+import java.util.Set;
+
+
+public class JavaPropertiesConfigurationParserTest {
+
+    public static Printer mPrinterConfig;
+    public static Format mFormatConfig;
+
+    public static File getResource(String fileName) {
+        ClassLoader classLoader = ClassLoader.getSystemClassLoader();
+        File resourceFile = new File(classLoader.getResource(fileName).getFile());
+        return resourceFile;
+    }
+
+    // Correct use testcases
+    @Test @BeforeAll
+    public static void testSuccessfulParsing() {
+        String defaultConfigPath = getResource("defaultConfig.properties").getAbsolutePath();
+        String configPath = getResource("dummyPrinterConfig.properties").getAbsolutePath();
+        Assertions.assertDoesNotThrow(() -> {
+            // Parse defaults
+            ConfigurationParser defaultPropertyParser = new JavaPropertiesConfigurationParser(defaultConfigPath);
+            Printer defaultPrinterConfig = defaultPropertyParser.getPrinter();
+            Format defaultFormatConfig = defaultPropertyParser.getFormat("default");
+
+            // Parse actual properties with defaults set
+            ConfigurationParser parser = new JavaPropertiesConfigurationParser(configPath, defaultPrinterConfig, defaultFormatConfig);
+            mPrinterConfig = parser.getPrinter();
+            Set<String> properties = mPrinterConfig.getPropertyNames();
+            Set<String> formats = parser.getFormatNames();
+            mFormatConfig = parser.getFormat("B5");
+        });
+    }
+    @Test
+    public void testCorrectValues() {
+        // default values - not overwritten
+        Assertions.assertEquals(35, mPrinterConfig.getProperty("max.charsPerLine").toInt());
+        Assertions.assertEquals(29, mPrinterConfig.getProperty("max.linesPerPage").toInt());
+
+        Assertions.assertEquals(10, mFormatConfig.getProperty("margin.left").toInt());
+
+        // overwritten values
+        Assertions.assertEquals(true, mPrinterConfig.getProperty("equidistantSupport").toBool());
+        Assertions.assertEquals(2.5, mPrinterConfig.getProperty("max.characterDistance").toDouble());
+
+        Assertions.assertEquals(176, mFormatConfig.getProperty("page.width").toInt());
+        Assertions.assertEquals(250, mFormatConfig.getProperty("page.height").toInt());
+
+        // values without default
+        Assertions.assertEquals("Index Everest-D V4", mPrinterConfig.getProperty("name").toString());
+
+        Assertions.assertEquals(false, mFormatConfig.getProperty("isPortrait").toBool());
+    }
+    @Test
+    public void testCompatibleTypeConversion() {
+        Assertions.assertEquals("35", mPrinterConfig.getProperty("max.charsPerLine").toString());
+        Assertions.assertEquals(false, mPrinterConfig.getProperty("max.characterDistance").toBool());
+
+        Assertions.assertEquals(250.0, mFormatConfig.getProperty("page.height").toDouble());
+    }
+    @Test
+    public void testFallbackProperties() {
+
+        String specifiedByConfig[] = {"name", "max.characterDistance", "equidistantSupport"};
+        String specifiedByFallback[] = {"max.charsPerLine", "max.linesPerPage"};
+
+        // config shall extend the fallback
+        HashSet<String> expectedPropertyNames = new HashSet<>(Arrays.asList(specifiedByConfig));
+        expectedPropertyNames.addAll(new HashSet<>(Arrays.asList(specifiedByFallback)));
+
+        HashSet<String> propertyNames = mPrinterConfig.getPropertyNames();
+        Assertions.assertEquals(expectedPropertyNames, propertyNames);
+    }
+
+
+    // Incorrect use testcases
+    @Test
+    public void testIllegalFile() {
+        Assertions.assertThrows(
+                ConfigurationParsingException.class,
+                () -> new JavaPropertiesConfigurationParser("nonexistent.properties")
+        );
+    }
+    @Test
+    public void testIllegalProperty() {
+        String configPath = getResource("illegalPropertyNameExample.properties").getAbsolutePath();
+        Assertions.assertThrows(
+                ConfigurationValidationException.class,
+                () -> new JavaPropertiesConfigurationParser(configPath)
+        );
+    }
+    @Test
+    public void testIllegalValue() {
+        String configPath = getResource("illegalPropertyValueExample.properties").getAbsolutePath();
+        Assertions.assertThrows(
+                ConfigurationValidationException.class,
+                () -> new JavaPropertiesConfigurationParser(configPath)
+        );
+    }
+    @Test
+    public void testNonexistentFormat() {
+        String configPath = getResource("defaultConfig.properties").getAbsolutePath();
+        Assertions.assertThrows(NoSuchElementException.class, () -> {
+            ConfigurationParser parser = new JavaPropertiesConfigurationParser(configPath);
+            parser.getFormat("B5");
+        });
+    }
+    @Test
+    public void testNonexistentProperties() {
+        String configPath = getResource("defaultConfig.properties").getAbsolutePath();
+        Assertions.assertThrows(NoSuchElementException.class, () -> {
+            ValidProperty spooderman = mPrinterConfig.getProperty("spooderman");
+        });
+        Assertions.assertThrows(NoSuchElementException.class, () -> {
+            ValidProperty doge = mFormatConfig.getProperty("doge");
+        });
+    }
+    @Test
+    public void testIncompatibleTypeConversion() {
+        Assertions.assertThrows(NumberFormatException.class, () -> mPrinterConfig.getProperty("equidistantSupport").toInt());
+        Assertions.assertThrows(NumberFormatException.class, () -> mPrinterConfig.getProperty("max.characterDistance").toInt());
+        Assertions.assertThrows(NumberFormatException.class, () -> mPrinterConfig.getProperty("name").toDouble());
+
+        Assertions.assertThrows(NumberFormatException.class, () -> mFormatConfig.getProperty("isPortrait").toDouble());
+    }
+
+}

src/test/resources/defaultConfig.properties

+# Default Printer Properties
+printer.max.charsPerLine=35
+printer.max.linesPerPage=29
+printer.equidistantSupport=false
+printer.max.characterDistance=2.5
+
+# Default Format Definition (assume A4 portrait)
+format.default.page.width=210
+format.default.page.height=297
+format.default.margin.left=10
+format.default.margin.top=10
+format.default.margin.right=10
+format.default.margin.bottom=10
\ No newline at end of file

src/test/resources/dummyPrinterConfig.properties

+# General Printer Properties
+printer.name=Index Everest-D V4
+printer.max.characterDistance=2.5
+printer.equidistantSupport=true
+
+# A4 Format
+format.A4.page.width=210
+format.A4.page.height=297
+
+# B5 Format
+format.B5.page.width=176
+format.B5.page.height=250
+format.B5.isPortrait=false
\ No newline at end of file

src/test/resources/illegalPropertyNameExample.properties

+# Default Printer Properties
+printer.max.charsPerLine=35
+printer.max.linesPerPage=29
+printer.equidistantSupport=false
+printer.max.characterDistance=2.5
+
+# Default Format Definition (assume A4 portrait)
+format.default.page.width=210
+fomrat.default.page.height=140
\ No newline at end of file

src/test/resources/illegalPropertyValueExample.properties

+# Default Printer Properties
+printer.max.charsPerLine=35
+printer.max.linesPerPage=29
+printer.equidistantSupport=false
+printer.max.characterDistance=2.5
+
+# Default Format Definition (assume A4 portrait)
+format.default.page.width=210
+format.default.page.height=abc
\ No newline at end of file