stub ADD_FEATURE reducer action

src/reducers/stateReducer.features.test.js

@@ -5,7 +5,7 @@ describe('Features', () => {
     features: [
       'low', 'high','back', 'rounded', 'sonorant', 
       'nasal', 'obstruent', 'occlusive', 'plosive', 
-      'prenasalized', 'aspirated', 'coronal', 'anterior'
+      'prenasalized', 'aspirated', 'coronal'
     ]
   };
   
@@ -14,4 +14,9 @@ describe('Features', () => {
     expect(stateReducer(state, action)).toBe(state);
   });
 
+  it('feature addition returns new feature list', () => {
+    const action = {type: 'ADD_FEATURE', value: {feature: 'anterior'}};
+    expect(stateReducer(state, action)).toEqual({...state, features:[...state.features, action.value.feature]})
+  })
+
 });

src/reducers/stateReducer.js

@@ -24,6 +24,11 @@ const stateReducer = (state, action) => {
       return {...state, lexicon: newLexicon}
     }
 
+    case 'ADD_FEATURE': {
+      let newFeature = action.value.feature;
+      return {...state, features:[...state.features, newFeature]}
+    }
+
     default:
       return state;
   }