Way to set the default behavior globally

README.md

@@ -170,6 +170,21 @@ try {
 }
 ```
 
+To define the **default behavior** globally you can call the function `setUnknownFeatureState`
+
+```js
+import { isEnabled, setEnabledFeatures, setUnknownFeatureState } from 'vue-feature-flipping'
+setUnknownFeatureState(true);
+
+setEnabledFeatures(['FF1', 'FF3'])
+
+isEnabled('FF1') // returns true cause the flag is here
+isEnabled('FF1', false) // returns true the flag is here
+isEnabled('FF2') // returns true cause the default behavior is true du to the previous setUnknownFeatureState calls
+isEnabled('FF2', false) // returns false cause the default behavior is passed as second argument
+
+```
+
 ### `not`: reversed rendering
 
 In some cases, we have to define a behavior when the feature is disabled.

src/service.ts

@@ -1,18 +1,25 @@
 import {ref, watch} from 'vue';
 
+const unknownFeatureState = ref<boolean>(false);
+
 const enabledFeatures = ref<string[] | null>(null);
 
-export function isEnabled(key: string, defaut = false) {
+export function isEnabled(key: string, defaut?: boolean) {
     const keys = enabledFeatures.value
-    return keys === null ? defaut : keys.includes(key)
+    const defaultValue = defaut === undefined ? unknownFeatureState.value : defaut;
+    return keys === null ? defaultValue : keys.includes(key)
+}
+
+export function setUnknownFeatureState(value: boolean) {
+    unknownFeatureState.value = value
 }
 
 export function setEnabledFeatures(features: string[] | null) {
     enabledFeatures.value = features
 }
 
 export function onFeaturesChanged(handler: () => void) {
-    return watch(enabledFeatures, (from, to) => {
+    return watch([enabledFeatures, unknownFeatureState], (from, to) => {
         handler()
     })
 }

tests/service.spec.ts

@@ -1,5 +1,5 @@
 import {isEnabled, setEnabledFeatures} from '../src'
-import {onFeaturesChanged} from "../src/service";
+import {onFeaturesChanged, setUnknownFeatureState} from "../src/service";
 import {nextTick} from "vue";
 
 describe('service', () => {
@@ -23,6 +23,21 @@ describe('service', () => {
         })
     })
 
+    describe('Unknown flag should return unknownFeatureState value', () => {
+        beforeEach(() => setEnabledFeatures(null))
+
+        it('Should return "default" value', () => {
+            setUnknownFeatureState(true)
+            expect(isEnabled('KEY', true)).toEqual(true)
+            expect(isEnabled('KEY', false)).toEqual(false)
+        })
+
+        it('Default "default" value is "true"', () => {
+            setUnknownFeatureState(true)
+            expect(isEnabled('KEY')).toEqual(true)
+        })
+    })
+
     describe('onFeaturesChanged', () => {
         it('Should call handler when features list updated', async () => {
             const handler = jest.fn()
@@ -44,6 +59,24 @@ describe('service', () => {
             expect(handler).toHaveBeenCalledTimes(3)
         })
 
+        it('Should call handler when unknownFeatureState updated', async () => {
+            setUnknownFeatureState(false)
+            const handler = jest.fn()
+            onFeaturesChanged(handler)
+
+            setUnknownFeatureState(false)
+            await nextTick()
+            expect(handler).toHaveBeenCalledTimes(0)
+
+            setUnknownFeatureState(true)
+            await nextTick()
+            expect(handler).toHaveBeenCalledTimes(1)
+
+            setUnknownFeatureState(false)
+            await nextTick()
+            expect(handler).toHaveBeenCalledTimes(2)
+        })
+
         it('Should return function to unsubscribe', async () => {
             const handler = jest.fn()
             const unsubscriber = onFeaturesChanged(handler)