feat(proxy-state-tree): now supports getters which are tracked

Author: christianalfoni

packages/node_modules/proxy-state-tree/src/Proxyfier.ts

@@ -197,6 +197,12 @@ export class Proxifier {
             if (typeof prop === 'symbol' || prop in Object.prototype)
               return target[prop]
 
+            const descriptor = Object.getOwnPropertyDescriptor(target, prop)
+
+            if (descriptor && 'get' in descriptor) {
+              return descriptor.get.call(proxifier.getProxyFromCache(path))
+            }
+
             const trackingTree = proxifier.getTrackingTree()
             const targetValue = target[prop]
             const nestedPath = proxifier.concat(path, prop)

packages/node_modules/proxy-state-tree/src/index.test.ts

@@ -887,3 +887,33 @@ describe('RESCOPING', () => {
     expect(tree.state.foo).toBe('bar2')
   })
 })
+
+describe('GETTER', () => {
+  it('should be able to define and track getters in the tree', () => {
+    let renderCount = 0
+    const tree = new ProxyStateTree({
+      user: {
+        firstName: 'Bob',
+        lastName: 'Goodman',
+        get fullName() {
+          return this.firstName + ' ' + this.lastName
+        },
+      },
+    })
+
+    const accessTree = tree.getTrackStateTree()
+    const mutationTree = tree.getMutationTree()
+
+    function render() {
+      accessTree.track(render)
+      accessTree.state.user.fullName
+      renderCount++
+    }
+
+    render()
+
+    mutationTree.state.user.firstName = 'Bob2'
+    tree.flush()
+    expect(renderCount).toBe(2)
+  })
+})