add code for jgrapht image gen

algorithms-miscellaneous-2/src/test/java/com/baeldung/jgrapht/GraphImageGenerationUnitTest.java

@@ -0,0 +1,47 @@
+package com.baeldung.jgrapht;
+
+import static org.junit.Assert.assertTrue;
+import java.awt.Color;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+import javax.imageio.ImageIO;
+import org.jgrapht.ext.JGraphXAdapter;
+import org.jgrapht.graph.DefaultDirectedGraph;
+import org.jgrapht.graph.DefaultEdge;
+import org.junit.Before;
+import org.junit.Test;
+import com.mxgraph.layout.mxCircleLayout;
+import com.mxgraph.layout.mxIGraphLayout;
+import com.mxgraph.util.mxCellRenderer;
+
+public class GraphImageGenerationUnitTest {
+    static DefaultDirectedGraph<String, DefaultEdge> g;
+
+    @Before
+    public void createGraph() throws IOException {
+        File imgFile = new File("src/test/resources/graph.png");
+        imgFile.createNewFile();
+        g = new DefaultDirectedGraph<String, DefaultEdge>(DefaultEdge.class);
+        String x1 = "x1";
+        String x2 = "x2";
+        String x3 = "x3";
+        g.addVertex(x1);
+        g.addVertex(x2);
+        g.addVertex(x3);
+        g.addEdge(x1, x2);
+        g.addEdge(x2, x3);
+        g.addEdge(x3, x1);
+    }
+
+    @Test
+    public void givenAdaptedGraph_whenWriteBufferedImage_ThenFileShouldExist() throws IOException {
+        JGraphXAdapter<String, DefaultEdge> graphAdapter = new JGraphXAdapter<String, DefaultEdge>(g);
+        mxIGraphLayout layout = new mxCircleLayout(graphAdapter);
+        layout.execute(graphAdapter.getDefaultParent());
+        File imgFile = new File("src/test/resources/graph.png");
+        BufferedImage image = mxCellRenderer.createBufferedImage(graphAdapter, null, 2, Color.WHITE, true, null);
+        ImageIO.write(image, "PNG", imgFile);
+        assertTrue(imgFile.exists());
+    }
+}