Add edge only once (#4)

* package: improve format

* graph: addEdge does nothing if edges already exists

* package: bump version to 0.1.4

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@okcontract/graph",
-  "version": "0.1.3",
+  "version": "0.1.4",
   "description": "Directed graph library",
   "private": false,
   "main": "dist/graph.umd.cjs",
@@ -32,7 +32,7 @@
     "definitions": "tsc --project tsconfig.build.json",
     "prepublishOnly": "npm run check && npm test && npm run build && npm run definitions",
     "check": "npx @biomejs/biome check src",
-    "format": "npx @biomejs/biome format src --write",
+    "format": "npx @biomejs/biome format src --write && npx @biomejs/biome check src --apply",
     "formatReadme": "prettier README.md --prose-wrap always --print-width 78 -w"
   },
   "repository": {
@@ -41,4 +41,4 @@
   },
   "author": "Henri Binsztok",
   "license": "MIT"
-}
+}

src/graph.test.ts

@@ -17,6 +17,15 @@ test("should add edges correctly", () => {
   expect(graph.get("a")).toEqual(["b"]);
 });
 
+test("does not add the same edge twice", () => {
+  const graph = new Graph<string>();
+  graph.addNode("a");
+  graph.addNode("b");
+  graph.addEdge("a", "b");
+  graph.addEdge("a", "b");
+  expect(graph.get("a")).toEqual(["b"]);
+});
+
 test("should return topological sort correctly", () => {
   const graph = new Graph<string>();
   graph.addNode("a");

src/graph.ts

@@ -51,6 +51,7 @@ export class Graph<T extends NodeId> {
   }
 
   addEdge(node1: T, node2: T): void {
+    if (this._adjacencyList.get(node1)?.includes(node2)) return;
     this._check(node1);
     this._check(node2);
     this._adjacencyList.get(node1)?.push(node2);