Fix delete schema when actual collection does not exist

spec/schemas.spec.js

@@ -744,4 +744,75 @@ describe('schemas', () => {
       done();
     });
   });
+
+  it('deletes schema when actual collection does not exist', done => {
+    request.post({
+      url: 'http://localhost:8378/1/schemas/NewClassForDelete',
+      headers: masterKeyHeaders,
+      json: true,
+      body: {
+        className: 'NewClassForDelete'
+      }
+    }, (error, response, body) => {
+      expect(error).toEqual(null);
+      expect(response.body.className).toEqual('NewClassForDelete');
+      request.del({
+        url: 'http://localhost:8378/1/schemas/NewClassForDelete',
+        headers: masterKeyHeaders,
+        json: true,
+      }, (error, response, body) => {
+        expect(response.statusCode).toEqual(200);
+        expect(response.body).toEqual({});
+        config.database.loadSchema().then(schema => {
+          schema.hasClass('NewClassForDelete').then(exist => {
+            expect(exist).toEqual(false);
+            done();
+          });
+        })
+      });
+    });
+  });
+
+  it('deletes schema when actual collection exists', done => {
+    request.post({
+      url: 'http://localhost:8378/1/schemas/NewClassForDelete',
+      headers: masterKeyHeaders,
+      json: true,
+      body: {
+        className: 'NewClassForDelete'
+      }
+    }, (error, response, body) => {
+      expect(error).toEqual(null);
+      expect(response.body.className).toEqual('NewClassForDelete');
+      request.post({
+        url: 'http://localhost:8378/1/classes/NewClassForDelete',
+        headers: restKeyHeaders,
+        json: true
+      }, (error, response, body) => {
+        expect(error).toEqual(null);
+        expect(typeof response.body.objectId).toEqual('string');
+        request.del({
+          url: 'http://localhost:8378/1/classes/NewClassForDelete/' + response.body.objectId,
+          headers: restKeyHeaders,
+          json: true,
+        }, (error, response, body) => {
+          expect(error).toEqual(null);
+          request.del({
+            url: 'http://localhost:8378/1/schemas/NewClassForDelete',
+            headers: masterKeyHeaders,
+            json: true,
+          }, (error, response, body) => {
+            expect(response.statusCode).toEqual(200);
+            expect(response.body).toEqual({});
+            config.database.loadSchema().then(schema => {
+              schema.hasClass('NewClassForDelete').then(exist => {
+                expect(exist).toEqual(false);
+                done();
+              });
+            });
+          });
+        });
+      });
+    });
+  });
 });

src/Routers/SchemasRouter.js

@@ -151,14 +151,20 @@ function deleteSchema(req) {
     throw new Parse.Error(Parse.Error.INVALID_CLASS_NAME, Schema.invalidClassNameMessage(req.params.className));
   }
 
-  return req.config.database.adaptiveCollection(req.params.className)
-    .then(collection => {
-      return collection.count()
-        .then(count => {
-          if (count > 0) {
-            throw new Parse.Error(255, `Class ${req.params.className} is not empty, contains ${count} objects, cannot drop schema.`);
-          }
-          return collection.drop();
+  return req.config.database.collectionExists(req.params.className)
+    .then(exist => {
+      if (!exist) {
+        return Promise.resolve();
+      }
+      return req.config.database.adaptiveCollection(req.params.className)
+        .then(collection => {
+          return collection.count()
+            .then(count => {
+              if (count > 0) {
+                throw new Parse.Error(255, `Class ${req.params.className} is not empty, contains ${count} objects, cannot drop schema.`);
+              }
+              return collection.drop();
+            })
         })
     })
     .then(() => {