Add get_edge_id test

test/graph_test.cpp

@@ -8,16 +8,18 @@
 // Example 1.
 TEST_CASE("GraphStructureTest") {
 
-    // Petersen Graph
     std::vector<std::vector<unsigned int>> adjacencies {
-        {2, 3, 4}, {1, 3, 7},
-        {2, 4, 8}, {3, 5, 9},
-        {1, 4, 10}, {1, 8, 9},
-        {2, 9, 10}, {3, 6, 10},
-        {4, 6, 7}, {5, 7, 8}
+		{2, 3}, 	//1
+		{1, 3, 4},	//2
+		{1, 2},		//3
+		{2}			//4
     };
     
     graph g = graph(adjacencies);
 
-    REQUIRE(g.num_nodes() == 10);
-}
\ No newline at end of file
+    REQUIRE(g.num_nodes() == 4);
+	REQUIRE(g.get_edge_id(1,2) == g.get_edge_id(2,1));
+	REQUIRE(g.get_edge_id(1,3) == g.get_edge_id(3,1));
+	REQUIRE(g.get_edge_id(2,4) == g.get_edge_id(4,2));
+
+}