Support adding students to a cohort via the instructor dashboard.

TNL-163

common/static/js/spec/string_utils_spec.js

@@ -0,0 +1,15 @@
+describe('interpolate_ntext', function () {
+    it('replaces placeholder values', function () {
+        expect(interpolate_ntext('contains {count} student',  'contains {count} students', 1, {count: 1})).
+            toBe('contains 1 student');
+        expect(interpolate_ntext('contains {count} student',  'contains {count} students', 5, {count: 2})).
+            toBe('contains 2 students');
+    });
+});
+
+describe('interpolate_text', function () {
+    it('replaces placeholder values', function () {
+        expect(interpolate_text('contains {adjective} students', {adjective: 'awesome'})).
+            toBe('contains awesome students');
+    });
+});