From eccc3597aa68113cf9d69c24caac7f63af8a8f41 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Garc=C3=ADa=20Aubert?=
 <danielgarciaaubert@gmail.com>
Date: Mon, 17 Jul 2017 19:43:59 +0200
Subject: [PATCH] Respond with 204 when vector tile is empty

---
 lib/cartodb/controllers/base.js |  4 +++
 test/acceptance/mvt.js          | 58 +++++++++++++++++++++++++++++++++
 test/support/test-client.js     | 16 ++++++---
 3 files changed, 73 insertions(+), 5 deletions(-)
 create mode 100644 test/acceptance/mvt.js

diff --git a/lib/cartodb/controllers/base.js b/lib/cartodb/controllers/base.js
index ab6587c2..7cdd0713 100644
--- a/lib/cartodb/controllers/base.js
+++ b/lib/cartodb/controllers/base.js
@@ -201,6 +201,10 @@ BaseController.prototype.sendError = function(req, res, err, label) {
 
     var statusCode = findStatusCode(err);
 
+    if (err.message === 'Tile does not exist' && req.params.format === 'mvt') {
+        statusCode = 204;
+    }
+
     debug('[%s ERROR] -- %d: %s, %s', label, statusCode, err, err.stack);
 
     // If a callback was requested, force status to 200
diff --git a/test/acceptance/mvt.js b/test/acceptance/mvt.js
new file mode 100644
index 00000000..17653d1d
--- /dev/null
+++ b/test/acceptance/mvt.js
@@ -0,0 +1,58 @@
+require('../support/test_helper');
+
+var assert = require('../support/assert');
+var TestClient = require('../support/test-client');
+
+function createMapConfig (sql) {
+    sql = sql || [
+        'select',
+        '   *',
+        'from',
+        '   populated_places_simple_reduced',
+    ].join('\n');
+
+    return {
+        version: '1.6.0',
+        layers: [{
+            type: "cartodb",
+            options: {
+                sql: sql,
+                cartocss: TestClient.CARTOCSS.POINTS,
+                cartocss_version: '2.3.0',
+                interactivity: 'cartodb_id'
+            }
+        }]
+    };
+}
+
+
+describe('mvt', function () {
+    const testCases = [
+        {
+            desc: 'should get empty mvt with code 204 (no content)',
+            coords: { z: 0, x: 0, y: 0 },
+            format: 'mvt',
+            mapConfig: createMapConfig('select 1 as cartodb_id, null::geometry as the_geom_webmercator')
+        }
+    ];
+
+    testCases.forEach(function (test) {
+        it(test.desc, done => {
+            const testClient = new TestClient(test.mapConfig, 1234);
+            const { z, x, y } = test.coords;
+            const options = {
+                format: test.format,
+                status: 204
+            };
+
+            testClient.getTile(z, x, y, options, (err, res) => {
+                assert.ifError(err);
+
+                assert.ifError(err);
+                assert.equal(res.statusCode, 204);
+                assert.equal(res.body, '');
+                testClient.drain(done);
+            });
+        });
+    });
+});
\ No newline at end of file
diff --git a/test/support/test-client.js b/test/support/test-client.js
index 659d6686..72a6eca9 100644
--- a/test/support/test-client.js
+++ b/test/support/test-client.js
@@ -525,7 +525,7 @@ TestClient.prototype.getTile = function(z, x, y, params, callback) {
             };
 
             var expectedResponse = {
-                status: 200,
+                status: params.status || 200,
                 headers: {
                     'Content-Type': 'application/json; charset=utf-8'
                 }
@@ -542,7 +542,12 @@ TestClient.prototype.getTile = function(z, x, y, params, callback) {
 
             if (isMvt) {
                 request.encoding = 'binary';
-                expectedResponse.headers['Content-Type'] = 'application/x-protobuf';
+
+                if (expectedResponse.status === 200) {
+                    expectedResponse.headers['Content-Type'] = 'application/x-protobuf';
+                } else if (expectedResponse.status === 204) {
+                    expectedResponse.headers['Content-Type'] = undefined;
+                }
             }
 
             var isGeojson = format.match(/geojson$/);
@@ -561,15 +566,16 @@ TestClient.prototype.getTile = function(z, x, y, params, callback) {
 
             assert.response(server, request, expectedResponse, function(res, err) {
                 assert.ifError(err);
-
                 var obj;
 
                 if (isPng) {
                     obj = mapnik.Image.fromBytes(new Buffer(res.body, 'binary'));
                 }
                 else if (isMvt) {
-                    obj = new mapnik.VectorTile(z, x, y);
-                    obj.setDataSync(new Buffer(res.body, 'binary'));
+                    if (res.body) {
+                        obj = new mapnik.VectorTile(z, x, y);
+                        obj.setDataSync(new Buffer(res.body, 'binary'));
+                    }
                 }
                 else {
                     obj = JSON.parse(res.body);