test coverage for existing class

src/main/java/com/rusefi/pcb/PcbMergeTool.java

@@ -84,7 +84,7 @@ public class PcbMergeTool {
         return null;
     }
 
-    static void mergePcb(PcbNode destNode, PcbNode source) throws IOException {
+    static void mergePcb(PcbNode destNode, PcbNode source) {
         /**
          * original local net name > new net name in combined PCB
          */
@@ -219,13 +219,17 @@ public class PcbMergeTool {
             net.setString(1, globalName);
     }
 
-    private static class Networks {
+    public static class Networks {
         /**
          * Net name > Net Id
          */
-        private Map<String, Integer> networks = new HashMap<>();
-        private Map<Integer, String> nameById = new HashMap<>();
+        private final Map<String, Integer> networks = new HashMap<>();
+        private final Map<Integer, String> nameById = new HashMap<>();
 
+        /**
+         * @param name current name
+         * @return new name for local network
+         */
         public String registerNetworkIfPcbSpecific(String name) {
             if (isLocalNetwork(name)) {
                 String newName = "F-0000" + networks.size();

src/main/java/com/rusefi/pcb/nodes/AddNetNode.java

@@ -1,7 +1,5 @@
 package com.rusefi.pcb.nodes;
 
-import com.rusefi.pcb.nodes.PcbNode;
-
 import java.util.List;
 
 /**

src/test/java/com/rusefi/pcb/NetworksTest.java

@@ -0,0 +1,40 @@
+package com.rusefi.pcb;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class NetworksTest {
+
+    private static final String GND = "GND";
+
+    @Test(expected = NullPointerException.class)
+    public void testNonExistent() {
+        PcbMergeTool.Networks n = new PcbMergeTool.Networks();
+
+        n.getId(GND);
+    }
+
+    @Test
+    public void testRegister() {
+        PcbMergeTool.Networks n = new PcbMergeTool.Networks();
+
+        n.registerNetworkIfPcbSpecific(GND);
+        assertEquals(0, n.getId(GND));
+
+        n.registerNetworkIfPcbSpecific(GND);
+        assertEquals(0, n.getId(GND));
+    }
+
+    @Test
+    public void testLocalNetwork() {
+        PcbMergeTool.Networks n = new PcbMergeTool.Networks();
+        n.registerNetworkIfPcbSpecific(GND);
+
+        String newName = n.registerNetworkIfPcbSpecific("N-00239");
+        assertEquals("F-00001", newName);
+        assertEquals(1, n.getId(newName));
+    }
+
+}