Upgrade immer to v2

package.json

@@ -17,7 +17,7 @@
     "test": "NODE_ENV=test ava"
   },
   "dependencies": {
-    "immer": "^1.3.0"
+    "immer": "^2.1.5"
   },
   "devDependencies": {
     "@babel/core": "^7.4.3",

src/duck.test.js

@@ -14,7 +14,7 @@ test('export methods', t => {
   t.is(typeof duck.createReducer, 'function', 'it should be a function');
 });
 
-test('Create action type', t => {
+test('create action type', t => {
   const TYPE_1 = duck.defineType('test1', 'TYPE'); // `test1` as prefix
   const TYPE_2 = duck.defineType('TYPE_2');
 
@@ -136,3 +136,39 @@ test('throw error if try to mutate reducer state', t => {
   );
   t.is(error2.message, 'Cannot add property id, object is not extensible');
 });
+
+// Test with Classes & Symbol
+test('support Classes & Symbol in reducer', t => {
+  class ClassA {}
+  class ClassB extends ClassA {}
+  const SymbolA = Symbol('a');
+
+  const UPDATE_CLASS_N_SYMBOL = duck.defineType('UPDATE_CLASS_N_SYMBOL');
+  const updateClassNSymbol = {
+    type: UPDATE_CLASS_N_SYMBOL,
+    payload: {
+      class: new ClassB(),
+      symbol: SymbolA,
+    },
+  };
+
+  const initState = {
+    class: new ClassA(),
+    symbol: undefined,
+  };
+  const testReducer = duck.createReducer(initState, {
+    [UPDATE_CLASS_N_SYMBOL]: (state, action) => {
+      return action.payload;
+    },
+  });
+  const testState = testReducer(initState, updateClassNSymbol);
+
+  t.deepEqual(
+    testState,
+    {
+      class: new ClassB(),
+      symbol: SymbolA,
+    },
+    'the reducer should work with Classes & Symbol'
+  );
+});

yarn.lock

@@ -2070,9 +2070,10 @@ ignore@^3.3.7:
   version "3.3.8"
   resolved "https://registry.yarnpkg.com/ignore/-/ignore-3.3.8.tgz#3f8e9c35d38708a3a7e0e9abb6c73e7ee7707b2b"
 
-immer@^1.3.0:
-  version "1.3.0"
-  resolved "https://registry.yarnpkg.com/immer/-/immer-1.3.0.tgz#b5c462dad2a129ad909eb4a180de63ffaa348d12"
+immer@^2.1.5:
+  version "2.1.5"
+  resolved "https://registry.yarnpkg.com/immer/-/immer-2.1.5.tgz#0389947455c5a2c7a47f1e6f415c9d1a62a1ebed"
+  integrity sha512-xyjQyTBYIeiz6jd02Hg12jV+9QISwF1crLcwTlzHpWH4e0ryNWj1kacpTwimK3bJV5NKKXw458G2vpqoB/inFA==
 
 import-fresh@^2.0.0:
   version "2.0.0"