Added testclass and implemented methods

test/search/breadthfirstsearch/EightPuzzleNodeTest.java

@@ -0,0 +1,87 @@
+package search.breadthfirstsearch;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class EightPuzzleNodeTest
+{
+    @Test
+    public void shouldThrowExceptionWhileStateHasDuplicateNumbers()
+    {
+        int[][] state = {
+                {1, 1, 3},
+                {4, 5, 6},
+                {7, 8, 0}
+        };
+
+        Assertions.assertThrows(IllegalArgumentException.class, () -> new EightPuzzleNode(state));
+    }
+
+    @Test
+    public void shouldThrowExceptionWhileStateHasNumbersOutOfRange()
+    {
+        int[][] state = {
+                {1, 2, 3},
+                {4, 5, 6},
+                {7, 8, 9}
+        };
+
+        Assertions.assertThrows(IllegalArgumentException.class, () -> new EightPuzzleNode(state));
+    }
+
+    @Test
+    public void shouldReturnTrueWhenTargetReached()
+    {
+        int[][] state = {
+                {1, 2, 3},
+                {4, 5, 6},
+                {7, 8, 0}
+        };
+
+        var node = new EightPuzzleNode(state);
+        var target = new EightPuzzleNode(state);
+
+        Assertions.assertTrue(node.isTargetReached(target));
+    }
+
+    @Test
+    public void shouldReturnFalseWhenTargetNotReached()
+    {
+        int[][] actualState = {
+                {7, 1, 6},
+                {0, 4, 2},
+                {3, 5, 8}
+        };
+
+        int[][] targetState = {
+                {1, 2, 3},
+                {4, 5, 6},
+                {7, 8, 0}
+        };
+
+        var node = new EightPuzzleNode(actualState);
+        var target = new EightPuzzleNode(targetState);
+
+        Assertions.assertFalse(node.isTargetReached(target));
+    }
+
+    @Test
+    public void shouldReturnNonEmptyListOfSuccessors()
+    {
+        int[][] state = {
+                {7, 1, 6},
+                {0, 4, 2},
+                {3, 5, 8}
+        };
+
+        var node = new EightPuzzleNode(state);
+        var successors = node.generateSuccessors();
+
+        Assertions.assertFalse(successors.isEmpty());
+    }
+
+}