Fix existsIn not working for symbols attached to arrays

src/utils/immutabilityHelpers.js

@@ -287,12 +287,5 @@ export function existsIn (json, path) {
     return true
   }
 
-  if (Array.isArray(json)) {
-    // index of an array
-    return existsIn(json[parseInt(path[0], 10)], path.slice(1))
-  }
-  else { // Object
-    // object property. find the index of this property
-    return existsIn(json[path[0]], path.slice(1))
-  }
+  return existsIn(json[path[0]], path.slice(1))
 }

src/utils/immutabilityHelpers.test.js

@@ -72,7 +72,7 @@ describe('immutabilityHelpers', () => {
     assert.throws(() => setIn(obj, ['a', 'b', 'c'], 4), /Path does not exist/)
   })
 
-  it.only('setIn non existing path with createPath=true', () => {
+  it('setIn non existing path with createPath=true', () => {
     const obj = {}
 
     assert.deepStrictEqual(setIn(obj, ['a', 'b', 'c'], 4, true), {
@@ -366,4 +366,25 @@ describe('immutabilityHelpers', () => {
     assert.deepStrictEqual(existsIn(json, ['obj', 'foo', 'bar']), false)
     assert.deepStrictEqual(existsIn(json, []), true)
   })
+  
+  it('existsIn should find symbols', () => {
+    const json = {
+      "obj": {
+        "arr": [1,2, {"first":3,"last":4}]
+      },
+      "str": "hello world",
+      "nill": null,
+      "bool": false
+    }
+
+    const symbol = Symbol('mySymbol')
+
+    const arrWithSymbol = [1, 2, 3]
+    arrWithSymbol[symbol] = 'yes'
+
+    assert.deepStrictEqual(existsIn(arrWithSymbol, [symbol]), true)
+    assert.deepStrictEqual(existsIn([1, 2, 3], [symbol]), false)
+    assert.deepStrictEqual(existsIn({ a: 1, [symbol]: 2 }, [symbol]), true)
+    assert.deepStrictEqual(existsIn({ a: 1 }, [symbol]), false)
+  })
 })