Update feasible-tree-test.js

test/rank/feasible-tree-test.js

@@ -1,29 +1,29 @@
-var expect = require("../chai").expect;
-var Graph = require("@dagrejs/graphlib").Graph;
-var feasibleTree = require("../../lib/rank/feasible-tree");
+let expect = require("../chai").expect;
+let Graph = require("@dagrejs/graphlib").Graph;
+let feasibleTree = require("../../lib/rank/feasible-tree");
 
 describe("feasibleTree", () => {
   it("creates a tree for a trivial input graph", () => {
-    var g = new Graph()
+    let g = new Graph()
       .setNode("a", { rank: 0 })
       .setNode("b", { rank: 1 })
       .setEdge("a", "b", { minlen: 1 });
 
-    var tree = feasibleTree(g);
+    let tree = feasibleTree(g);
     expect(g.node("b").rank).to.equal(g.node("a").rank + 1);
     expect(tree.neighbors("a")).to.eql(["b"]);
   });
 
   it("correctly shortens slack by pulling a node up", () => {
-    var g = new Graph()
+    let g = new Graph()
       .setNode("a", { rank: 0 })
       .setNode("b", { rank: 1 })
       .setNode("c", { rank: 2 })
       .setNode("d", { rank: 2 })
       .setPath(["a", "b", "c"], { minlen: 1 })
       .setEdge("a", "d", { minlen: 1 });
 
-    var tree = feasibleTree(g);
+    let tree = feasibleTree(g);
     expect(g.node("b").rank).to.eql(g.node("a").rank + 1);
     expect(g.node("c").rank).to.eql(g.node("b").rank + 1);
     expect(g.node("d").rank).to.eql(g.node("a").rank + 1);
@@ -34,7 +34,7 @@ describe("feasibleTree", () => {
   });
 
   it("correctly shortens slack by pulling a node down", () => {
-    var g = new Graph()
+    let g = new Graph()
       .setNode("a", { rank: 2 })
       .setNode("b", { rank: 0 })
       .setNode("c", { rank: 2 })