fix(mutation): create a new state instead of mutating initialValues t…

…o prevent readonly errors

src/examples/index.tsx

@@ -6,18 +6,27 @@ import Geschichte, { factoryParameters, pm, serializers } from '../index'
 const history = createBrowserHistory()
 
 const config = {
+  abc: {
+    test: pm('z', serializers.string)
+  },
   arg: pm('arg', serializers.string),
   test: pm('foo', serializers.string)
 }
 
 const { useQuery } = factoryParameters(config, {
+  abc: {
+    test: 'arg'
+  },
   arg: 'blub',
   test: 'haha'
 })
 
 const { useQuery: useAnotherQuery } = factoryParameters(
   config,
   {
+    abc: {
+      test: 'arg'
+    },
     arg: 'xyz',
     test: 'another'
   },
@@ -59,7 +68,7 @@ const DifferentApp = () => {
 export const App = () => (
   <>
     <Geschichte history={history}>
-      <h3>A sample Applications</h3>
+      <h3>A sample Appliations</h3>
       <InnerApp />
       <DifferentApp />
     </Geschichte>

src/geschichte.stories.mdx

@@ -34,4 +34,6 @@ export const App = () => (
 
 ## Test
 
-<App />
+<Preview>
+    <App />
+</Preview>

src/lib/store.ts

@@ -1,7 +1,7 @@
 /* tslint:disable:no-expression-statement readonly-array no-shadowed-variable */
 import { History } from 'history'
 import LocationState = History.LocationState
-
+import produce from 'immer'
 import memoizeOne from 'memoize-one'
 import { stringify } from 'query-string'
 import {
@@ -79,18 +79,23 @@ export const factoryParameters = <T = object>(
   const initBlank = (initialQueries: object) => {
     // thisValues will be mutated by applyFlatConfigToState, that's why we init it with a copy of
     // the initial state.
-    const thisValues = { ...defaultInitialValues }
-    const thisQuery = applyFlatConfigToState(
-      flatConfig,
-      initialQueries,
-      ns,
-      thisValues,
-      defaultInitialValues
-    )
+    // tslint:disable-next-line:no-let
+    let thisQuery = {}
+    // We produce a new state here instead of mutating defaultInitialValues.
+    // Otherwise it's possible that it get's reused across executions and that will yield to readonly errors.
+    const values = produce(defaultInitialValues, draft => {
+      thisQuery = applyFlatConfigToState(
+        flatConfig,
+        initialQueries,
+        ns,
+        draft as T,
+        defaultInitialValues as T
+      )
+    })
     return {
       initialValues: defaultInitialValues,
       query: thisQuery,
-      values: thisValues
+      values
     }
   }