feat(proxy-state-tree): don't allow nesting proxies in state tree

Author: FWeinb

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

@@ -66,6 +66,19 @@ describe('OBJECTS', () => {
         tree.get().foo = 'bar2'
       }).toThrow()
     })
+    test('should throw if parts of state are nested', () => {
+      const state = {
+        foo: {
+          nested: 'bar',
+        },
+      }
+      const tree = new ProxyStateTree(state)
+      expect(() => {
+        tree.startMutationTracking()
+        tree.get().foo = tree.get().foo
+        tree.clearMutationTracking()
+      }).toThrowError(/exists in the state tree on path "foo"/i)
+    })
     test('should track SET mutations', () => {
       const state = {
         foo: 'bar',
@@ -228,6 +241,23 @@ describe('ARRAYS', () => {
         tree.get().foo.push('foo')
       }).toThrow()
     })
+    test('should throw if parts of state are nested', () => {
+      const state = {
+        foo: [undefined],
+        bar: {
+          nested: 'baz',
+        },
+      }
+      const tree = new ProxyStateTree(state)
+      tree.startMutationTracking()
+
+      // Property mutation
+      expect(() => {
+        tree.get().foo[0] = tree.get().bar
+      }).toThrowError(/exists in the state tree on path "bar"/i)
+
+      tree.clearMutationTracking()
+    })
     test('should track PUSH mutations', () => {
       const state = {
         foo: [],

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

@@ -84,7 +84,13 @@ function createArrayProxy(tree, value, path) {
           `proxy-state-tree - You are mutating the path "${nestedPath}", but it is not allowed`
         )
       }
-
+      if (value[IS_PROXY] === true) {
+        throw new Error(
+          `proxy-state-tree - You are trying to insert a value that already exists in the state tree on path "${
+            value[PATH]
+          }"`
+        )
+      }
       tree.currentMutations.push({
         method: 'set',
         path: nestedPath,
@@ -131,6 +137,13 @@ function createObjectProxy(tree, value, path) {
           `proxy-state-tree - You are mutating the path "${nestedPath}", but it is not allowed`
         )
       }
+      if (value[IS_PROXY] === true) {
+        throw new Error(
+          `proxy-state-tree - You are trying to insert a value that already exists in the state tree on path "${
+            value[PATH]
+          }"`
+        )
+      }
       if (shouldTrackMutations(tree, nestedPath)) {
         if (!(prop in target)) {
           tree.objectChanges.add(path)