Improve test coverage (just a tiny bit)

src/libs/middlewares/id2str.js

@@ -37,5 +37,8 @@ module.exports = {
     transform,
     gender,
     period,
-    schoolYear
+    schoolYear,
+    admDependency,
+    location,
+    ethnicGroup
 };

src/test/enrollment.js

@@ -180,7 +180,7 @@ describe('request enrollments', () => {
 
     it('should list enrollments with valid dimensions', (done) => {
         chai.request(server)
-            .get('/api/v1/enrollment?dims=region,state,adm_dependency,location&filter=min_year:2014,region:4')
+            .get('/api/v1/enrollment?dims=region,state,adm_dependency,location,gender,period,education_level,location,ethnic_group')
             .end((err, res) => {
                 res.should.have.status(200);
                 res.should.be.json;