feat: solution for 'Повторный экзамен #2: Граф с рефлексией на код'

tests/graph.test.js

@@ -0,0 +1,55 @@
+const Graph = require('../src/index');
+
+describe('Graph with reflexivity', () => {
+  let g;
+
+  beforeEach(() => {
+    g = new Graph();
+  });
+
+  test('adding a node creates reflexive edge', () => {
+    g.addNode('A');
+    expect(g.nodes()).toContain('A');
+    expect(g.hasEdge('A', 'A')).toBe(true);
+  });
+
+  test('adding an edge between existing nodes', () => {
+    g.addNode('A');
+    g.addNode('B');
+    g.addEdge('A', 'B');
+    expect(g.hasEdge('A', 'B')).toBe(true);
+    expect(g.hasEdge('B', 'A')).toBe(false);
+  });
+
+  test('adding an edge automatically adds missing nodes', () => {
+    g.addEdge('X', 'Y');
+    expect(g.nodes()).toEqual(expect.arrayContaining(['X', 'Y']));
+    expect(g.hasEdge('X', 'Y')).toBe(true);
+    // reflexive edges for both nodes
+    expect(g.hasEdge('X', 'X')).toBe(true);
+    expect(g.hasEdge('Y', 'Y')).toBe(true);
+  });
+
+  test('getNeighbors returns correct neighbors', () => {
+    g.addNode('1');
+    g.addNode('2');
+    g.addEdge('1', '2');
+    expect(g.getNeighbors('1')).toEqual(expect.arrayContaining(['1', '2']));
+    expect(g.getNeighbors('2')).toEqual(['2']);
+  });
+
+  test('edges method returns all edges', () => {
+    g.addNode('A');
+    g.addNode('B');
+    g.addEdge('A', 'B');
+    const edges = g.edges();
+    expect(edges).toEqual(
+      expect.arrayContaining([
+        ['A', 'A'],
+        ['B', 'B'],
+        ['A', 'B']
+      ])
+    );
+    expect(edges.length).toBe(3);
+  });
+});