preserve transient traits, add test

Author: khvn26

flagsmith-core.ts

@@ -112,7 +112,8 @@ const Flagsmith = class {
                 };
             });
             traits.forEach(trait => {
-                userTraits[trait.trait_key.toLowerCase().replace(/ /g, '_')] = trait.trait_value
+                userTraits[trait.trait_key.toLowerCase().replace(/ /g, '_')] = trait.transient ? 
+                    {transient: true, value: trait.trait_value} : trait.trait_value
             });
 
             this.oldFlags = { ...this.flags };

test/cache.test.ts

@@ -8,6 +8,7 @@ import {
     testIdentity,
 } from './test-constants';
 import SyncStorageMock from './mocks/sync-storage-mock';
+import { promises as fs } from 'fs'
 
 describe('Cache', () => {
 
@@ -282,4 +283,34 @@ describe('Cache', () => {
             },
         );
     });
+    test('should cache transient traits correctly', async () => {
+        const onChange = jest.fn();
+        const testIdentityWithTransientTraits = 'test_identity_with_transient_traits'
+        const { flagsmith, initConfig, AsyncStorage, mockFetch } = getFlagsmith({
+            cacheFlags: true,
+            identity: testIdentityWithTransientTraits,
+            traits: {
+                transient_trait: {
+                    value: 'Example',
+                    transient: true,
+                }
+            },
+            onChange,
+        });
+        mockFetch.mockResolvedValueOnce({status: 200, text: () => fs.readFile(`./test/data/identities_${testIdentityWithTransientTraits}.json`, 'utf8')})
+        await flagsmith.init(initConfig);
+        expect(onChange).toHaveBeenCalledTimes(1);
+        expect(mockFetch).toHaveBeenCalledTimes(1);
+        expect(getStateToCheck(flagsmith.getState())).toEqual({
+            ...identityState,
+            identity: testIdentityWithTransientTraits,
+            traits: {
+                ...identityState.traits,
+                transient_trait: {
+                    transient: true,
+                    value: 'Example',
+                }
+            }
+        })
+    });
 });

test/data/identities_test_identity_with_transient_traits.json

@@ -55,6 +55,11 @@
         {
             "trait_key": "string_trait",
             "trait_value": "Example"
+        },
+        {
+            "trait_key": "transient_trait",
+            "trait_value": "Example",
+            "transient": true
         }
     ]
 }

test/test-constants.ts

@@ -44,16 +44,6 @@ export const identityState = {
         off_value: { id: 80319, enabled: false, value: null },
     },
 };
-export const identityLocalState = {
-    ...identityState,
-    'traits': {
-        ...identityState.traits,
-        'transient_trait': {
-            'value': 'Example',
-            'transient': true,
-        }
-    }
-};
 export const defaultStateAlt = {
     ...defaultState,
     flags: {

types.d.ts

@@ -112,6 +112,7 @@ export interface IFlagsmithResponse {
     traits?: {
         trait_key: string;
         trait_value: IFlagsmithValue;
+        transient?: boolean;
     }[];
     flags?: {
         enabled: boolean;