Added errors store with tests

frontend/stores/ErrorsStore.test.js

@@ -0,0 +1,27 @@
+/* eslint-disable */
+import ErrorsStore from './ErrorsStore';
+
+// Actions
+describe('ErrorsStore', () => {
+  let store;
+
+  beforeEach(() => {
+    store = new ErrorsStore();
+  });
+
+  test('#add should add errors', () => {
+    expect(store.errors.length).toBe(0);
+    store.add('first error');
+    store.add('second error');
+    expect(store.errors.length).toBe(2);
+  });
+
+  test('#remove should remove errors', () => {
+    store.add('first error');
+    store.add('second error');
+    expect(store.errors.length).toBe(2);
+    store.remove(0);
+    expect(store.errors.length).toBe(1);
+    expect(store.errors[0]).toBe('second error');
+  });
+});