Selectors: Add areAllSitesSingleUser

client/state/selectors/are-all-sites-single-user.js

@@ -0,0 +1,16 @@
+/**
+ * Internal dependencies
+ */
+import createSelector from 'lib/create-selector';
+import { isSingleUserSite } from 'state/sites/selectors';
+
+/**
+ * Returns true if every site of the current user is a single user site
+ *
+ * @param  {Object}  state Global state tree
+ * @return {Boolean}       True if all sites are single user sites
+ */
+export default createSelector( ( state ) => {
+	const siteIds = Object.keys( state.sites.items );
+	return siteIds && siteIds.every( ( siteId ) => isSingleUserSite( state, siteId ) );
+}, ( state ) => ( state.sites.items ) );

client/state/selectors/index.js

@@ -13,6 +13,7 @@
  * to its individual file.
  */
 
+export areAllSitesSingleUser from './are-all-sites-single-user';
 export areSitePermalinksEditable from './are-site-permalinks-editable';
 export canCurrentUser from './can-current-user';
 export countPostLikes from './count-post-likes';

client/state/selectors/test/are-all-sites-single-user.js

@@ -0,0 +1,51 @@
+/**
+ * External dependencies
+ */
+import { expect } from 'chai';
+
+/**
+ * Internal dependencies
+ */
+import { areAllSitesSingleUser } from '../';
+
+describe( 'areAllSitesSingleUser()', () => {
+	it( 'should return false if single_user_site isn\'t true for all sites', () => {
+		const state = {
+			sites: {
+				items: {
+					2916284: {
+						ID: 2916284,
+						single_user_site: true
+					},
+					2916285: {
+						ID: 2916285,
+						single_user_site: false
+					}
+				}
+			}
+		};
+
+		const allAreSingleUser = areAllSitesSingleUser( state );
+		expect( allAreSingleUser ).to.be.false;
+	} );
+
+	it( 'should return true if single_user_site is true for all sites', () => {
+		const state = {
+			sites: {
+				items: {
+					2916284: {
+						ID: 2916284,
+						single_user_site: true
+					},
+					2916285: {
+						ID: 2916285,
+						single_user_site: true
+					}
+				}
+			}
+		};
+
+		const allAreSingleUser = areAllSitesSingleUser( state );
+		expect( allAreSingleUser ).to.be.true;
+	} );
+} );