[#757] Add validator that detects the cyclic imports. Change API for printBF

Author: opatrascoiu

dmn-core/src/main/java/com/gs/dmn/Graph.java

@@ -15,7 +15,6 @@
 import com.gs.dmn.runtime.Pair;
 
 import java.io.IOException;
-import java.io.StringWriter;
 import java.io.Writer;
 import java.util.*;
 import java.util.function.Function;
@@ -156,18 +155,18 @@ public void printNodes(Writer writer, Function<T, String> nodeInfo) throws IOExc
         }
     }
 
-    public void printBF(T rootNode, StringWriter writer, Function<T, String> nodeInfo) {
+    public void printBF(T rootNode, Writer writer, Function<T, String> nodeInfo) throws IOException {
         printBF(rootNode, writer, nodeInfo, x -> true);
     }
 
-    public void printBF(T rootNode, StringWriter writer, Function<T, String> nodeInfo, Predicate<T> filter) {
+    public void printBF(T rootNode, Writer writer, Function<T, String> nodeInfo, Predicate<T> filter) throws IOException {
         Set<T> visited = new LinkedHashSet<>();
         if (filter.test(rootNode)) {
             printBF(rootNode, writer, nodeInfo, filter, 0, visited);
         }
     }
 
-    private void printBF(T node, StringWriter writer, Function<T, String> nodeInfo, Predicate<T> filter, int level, Set<T> visited) {
+    private void printBF(T node, Writer writer, Function<T, String> nodeInfo, Predicate<T> filter, int level, Set<T> visited) throws IOException {
         String indent = "\t".repeat(level);
         writer.write(indent + nodeInfo.apply(node) + "\n");
         if (!visited.contains(node)) {

dmn-core/src/test/java/com/gs/dmn/GraphTest.java

@@ -148,11 +148,11 @@ void testPrintNodes() throws IOException {
         StringWriter writer = new StringWriter();
         graph.printNodes(writer, this::nodeInfo);
         String expectedNodes = "1\n2\n3\n4\n";
-        assertEquals(expectedNodes, writer.getBuffer().toString());
+        assertEquals(expectedNodes, writer.toString());
     }
 
     @Test
-    void testPrintTree() {
+    void testPrintTree() throws IOException {
         Graph<Integer> graph = new Graph<>();
         graph.addEdge(1, 2);
         graph.addEdge(2, 3);
@@ -171,7 +171,7 @@ void testPrintTree() {
                         \t\t\t4
                         \t\t\t\t2
                         """;
-        assertEquals(expectedNodes, writer.getBuffer().toString());
+        assertEquals(expectedNodes, writer.toString());
     }
 
     private String nodeInfo(Integer node) {