Fix bad edge creation on shortestPaths function

Author: krm35

src/index.ts

@@ -397,9 +397,14 @@ export function Graph(serialized?: Serialized) {
       removedEdges = [],
       weight = path.weight;
     while (weight) {
-      removeEdge(path[0], path[1]);
-      removeEdge(path[1], path[0]);
-      removedEdges.push([path[0], path[1]]);
+      if (hasEdge(path[0], path[1])) {
+        removeEdge(path[0], path[1]);
+        removedEdges.push([path[0], path[1]]);
+      }
+      if (hasEdge(path[1], path[0])) {
+        removeEdge(path[1], path[0]);
+        removedEdges.push([path[1], path[0]]);
+      }
       try {
         path = shortestPath(source, destination);
         if (!path.weight || weight < path.weight) break;
@@ -408,10 +413,7 @@ export function Graph(serialized?: Serialized) {
         break;
       }
     }
-    for (const [u, v] of removedEdges) {
-      addEdge(u, v);
-      addEdge(v, u);
-    }
+    for (const [u, v] of removedEdges) addEdge(u, v);
     return paths;
   }
 

test.js

@@ -427,7 +427,7 @@ describe("Graph", function () {
       );
     });
 
-    it("Should compute shortest paths on six edges.", function () {
+    it("Should compute shortest paths.", function () {
       var graph = Graph()
         .addEdge("a", "b")
         .addEdge("b", "c")
@@ -444,6 +444,9 @@ describe("Graph", function () {
       const nodes = ["a", "b", "c", "d", "e", "f"];
       assert.equal(graph.nodes().length, nodes.length);
       nodes.forEach((node) => assert(contains(graph.nodes(), node)));
+      // check edges are still there and no new have been added
+      assert.deepEqual(graph.hasEdge("a", "b"), true);
+      assert.deepEqual(graph.hasEdge("b", "a"), false);
     });
   });
 
@@ -458,11 +461,7 @@ describe("Graph", function () {
 });
 
 function contains(arr, item) {
-  return (
-    arr.filter(function (d) {
-      return d === item;
-    }).length > 0
-  );
+  return arr.includes(item);
 }
 
 function comesBefore(arr, a, b) {