test: add core unit tests

- Add JUnit 5 Jupiter dependencies to pom.xml
- Add maven-surefire-plugin for test execution
- Add AbstractShapeTest for base class methods
- Add SCircleTest, SRectangleTest, STriangleTest, STextTest

Tests cover: creation, bounds, clone, resize (AbstractShape)

pom.xml

@@ -6,8 +6,9 @@
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <maven.compiler.source>1.10</maven.compiler.source>
-        <maven.compiler.target>1.10</maven.compiler.target>
+        <maven.compiler.source>16</maven.compiler.source>
+        <maven.compiler.target>16</maven.compiler.target>
+        <maven.testSourceDirectory>test/java</maven.testSourceDirectory>
     </properties>
     <build>
         <plugins>
@@ -19,6 +20,11 @@
                     <target>16</target>
                 </configuration>
             </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.2.5</version>
+            </plugin>
         </plugins>
     </build>
 
@@ -38,5 +44,19 @@
             <artifactId>logback-classic</artifactId>
             <version>RELEASE</version>
         </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>5.10.0</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>5.10.0</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
-</project>
+</project>