Improve data model & fix tests

backend/src/Model/spec/Edge.spec.ts

@@ -1,14 +1,27 @@
-import { Edge, TreeNode } from '../'
-import { expect } from 'chai';
-import 'mocha';
+import { Edge, TreeNode, TreeNodeFactory } from '../'
+import { expect } from 'chai'
+import 'mocha'
 
 describe('Edge', () => {
-
   it('should contain a name', () => {
       let e = new Edge('foo')
       expect(e.name).to.equal('foo')
   });
 
+  it('firstEdge should retireve the first edge', () => {
+    const topics = 'foo/bar/baz'.split('/')
+    const leaf = TreeNodeFactory.fromEdgesAndValue(topics, 5)
+    let bazEdge = leaf.sourceEdge
+
+    if (!bazEdge) {
+      expect.fail('should not be undefined')
+      return;
+    }
+
+    expect(bazEdge.name).to.eq('baz')
+    expect(bazEdge.firstEdge().name).to.eq('foo')
+  });
+
   it('hash should not be empty', () => {
       let e = new Edge('bar')
       expect(e.hash().length).to.be.gt(0)
@@ -20,12 +33,17 @@ describe('Edge', () => {
       expect(e.hash()).to.eq(previousHash)
   });
 
-  it('hash should change when parent is present', () => {
-      let foo = new Edge('foo')
-      let bar = new Edge('bar')
+  it('hash should include change if parents are different', () => {
+    const topics1 = 'foo/bar/baz'.split('/')
+    const bazEdge1 = TreeNodeFactory.fromEdgesAndValue(topics1, 5).sourceEdge
 
-      var previousHash = bar.hash()
-      bar.source = new TreeNode(foo, undefined)
-      expect(bar.hash()).to.not.eq(previousHash)
+    const topics2 = 'foo/foo/baz'.split('/')
+    const bazEdge2 = TreeNodeFactory.fromEdgesAndValue(topics2, 5).sourceEdge
+
+    if (!bazEdge1 || !bazEdge2) {
+      throw Error('should not happen')
+    }
+
+    expect(bazEdge1.hash()).to.not.eq(bazEdge2.hash())
   });
 });