Database version in features (#5627)

* adding database.version in the serverInfo (only MongoDB, it gives undefined when using Postgres)

* . correction of old 'features' tests
. adding engine and database in the StorageAdapter interface and implementations

* . version retrieval done in performInitialization
. PostgreSQL version

* performInitialization now returns a Promise

spec/features.spec.js

@@ -3,20 +3,41 @@
 const request = require('../lib/request');
 
 describe('features', () => {
-  it('requires the master key to get features', done => {
-    request({
+  it('should return the serverInfo', async () => {
+    const response = await request({
       url: 'http://localhost:8378/1/serverInfo',
       json: true,
       headers: {
         'X-Parse-Application-Id': 'test',
         'X-Parse-REST-API-Key': 'rest',
+        'X-Parse-Master-Key': 'test',
       },
-    }).then(fail, response => {
-      expect(response.status).toEqual(403);
-      expect(response.data.error).toEqual(
-        'unauthorized: master key is required'
-      );
-      done();
     });
+    const data = response.data;
+    expect(data).toBeDefined();
+    expect(data.features).toBeDefined();
+    expect(data.parseServerVersion).toBeDefined();
+    expect(data.database).toBeDefined();
+    expect(['MongoDB', 'PostgreSQL']).toContain(data.database.engine);
+  });
+
+  it('requires the master key to get features', async done => {
+    try {
+      await request({
+        url: 'http://localhost:8378/1/serverInfo',
+        json: true,
+        headers: {
+          'X-Parse-Application-Id': 'test',
+          'X-Parse-REST-API-Key': 'rest',
+        },
+      });
+      done.fail(
+        'The serverInfo request should be rejected without the master key'
+      );
+    } catch (error) {
+      expect(error.status).toEqual(403);
+      expect(error.data.error).toEqual('unauthorized: master key is required');
+      done();
+    }
   });
 });