Add tests for listings redux module

src/redux/modules/listings.js

@@ -24,7 +24,7 @@ const initialState = {
   entries: {},
 };
 
-const entries = (state = initialState.entries, action) => {
+export const entries = (state = initialState.entries, action) => {
   switch (action.type) {
     case ADD_ENTRY:
       return {

src/redux/modules/listings.test.js

@@ -0,0 +1,87 @@
+import {
+  entries as entriesReducer,
+  addEntry,
+  modifyEntry,
+  deleteEntry,
+} from './listings';
+
+describe('listings modules test', () => {
+  describe('entries reducer test', () => {
+    it('should return the initial state', () => {
+      expect(entriesReducer(undefined, {})).toEqual({});
+    });
+
+    it('should add an entry correctly', () => {
+      expect(
+        entriesReducer(
+          {
+            init: {
+              code: '1234',
+              name: 'revan',
+            },
+          },
+          addEntry('id', 'malak', '1412')
+        )
+      ).toEqual({
+        init: {
+          code: '1234',
+          name: 'revan',
+        },
+        id: {
+          code: '1412',
+          name: 'malak',
+        },
+      });
+    });
+
+    it('should modify (the code) an entry correctly', () => {
+      expect(
+        entriesReducer(
+          {
+            init: {
+              code: '1234',
+              name: 'revan',
+            },
+            id: {
+              code: '1412',
+              name: 'malak',
+            },
+          },
+          modifyEntry('init', '9999')
+        )
+      ).toEqual({
+        init: {
+          code: '9999',
+          name: 'revan',
+        },
+        id: {
+          code: '1412',
+          name: 'malak',
+        },
+      });
+    });
+
+    it('should delete an entry correctly', () => {
+      expect(
+        entriesReducer(
+          {
+            init: {
+              code: '1234',
+              name: 'revan',
+            },
+            id: {
+              code: '1412',
+              name: 'malak',
+            },
+          },
+          deleteEntry('init')
+        )
+      ).toEqual({
+        id: {
+          code: '1412',
+          name: 'malak',
+        },
+      });
+    });
+  });
+});