diff --git a/tests/tutorials.js b/tests/tutorials.js
index cd3d10969b..aac0eab890 100644
--- a/tests/tutorials.js
+++ b/tests/tutorials.js
@@ -58,14 +58,25 @@ describe('tutorials', function () {
               tut$.when.apply(tut$, deferreds).fail(function () {
                 throw new Error('Idle functions were rejected');
               }).then(function () {
+                var subtestDeferreds = [];
                 test.data('tests').forEach(function (testExp) {
-                  var result = targetWindow.eval(testExp);
-                  /* If the result isn't truthy, make sure our expect has a
-                   * description telling which test block and specific test
-                   * failed. */
-                  expect(result).toBeTruthy(test.data('description') + ' -> ' + testExp);
+                  /* The test expression can return a value or a promise.  We
+                   * use jQuery's when to generically get the results in a
+                   * resolution function.  A rejection is a failure. */
+                  var testResult = targetWindow.eval(testExp);
+                  var subtestDefer = tut$.when(testResult).done(function (result) {
+                    /* If the result isn't truthy, make sure our expect has a
+                     * description telling which test block and specific test
+                     * failed. */
+                    expect(result).toBeTruthy(test.data('description') + ' -> ' + testExp);
+                  }).fail(function () {
+                    expect(false).toBeTruthy(test.data('description') + ' promise failed -> ' + testExp);
+                  });
+                  subtestDeferreds.push(subtestDefer);
+                });
+                tut$.when.apply(tut$, subtestDeferreds).then(function () {
+                  testDefer.resolve();
                 });
-                testDefer.resolve();
               });
             };
             /* If we have already run the specific codeblock, don't run it
diff --git a/tutorials/basic/thumb.jpg b/tutorials/basic/thumb.jpg
new file mode 100755
index 0000000000..1892cbbbfc
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diff --git a/tutorials/tile_source/thumb.jpg b/tutorials/tile_source/thumb.jpg
new file mode 100755
index 0000000000..9f3af56a96
Binary files /dev/null and b/tutorials/tile_source/thumb.jpg differ
diff --git a/tutorials/wms/index.pug b/tutorials/wms/index.pug
index 0d959dd246..da0e0acf40 100644
--- a/tutorials/wms/index.pug
+++ b/tutorials/wms/index.pug
@@ -18,43 +18,46 @@ block mainTutorial
     });
     // place a base tile layer on the map
     map.createLayer('osm');
+
+    // define a function that, given a tile location, returns a URL with
+    // appropriate parameters for a WMS server
+    function getWMSURL(x, y, zoom) {
+      var service = 'NWS_Observations';
+      var observation = 'radar_base_reflectivity';
+      // get data from NOAA
+      var baseUrl = 'https://idpgis.ncep.noaa.gov/arcgis/rest/services/' + service + '/' + observation + '/MapServer/export';
+      // Get the bounding box of the tile in the desired projection
+      var bb = this.gcsTileBounds({x: x, y: y, level: zoom}, projection);
+      // Set the WMS server parameters
+      var params = {
+        transparent: true,
+        format: 'png32',
+        bbox: bb.left + ',' + bb.bottom + ',' + bb.right + ',' + bb.top,
+        bboxSR: projection.split(':')[1],
+        imageSR: projection.split(':')[1],
+        size: '256,256',
+        layers: 'show:3',
+        f: 'image'
+      }
+      // construct the url for a tile.  We can use jQuery's $.param function.
+      var url =  baseUrl + '?' + $.param(params);
+      return url;
+    }
+
     // create a tile layer with the WMS data
     map.createLayer('osm', {
-      attribution: null,
+      attribution: 'Data from <a href="https://idpgis.ncep.noaa.gov/arcgis/rest/services/NWS_Observations/">NOAA</a>',
       // the tiles are transparent, so don't keep the lower level ones; they
       // would build up
       keepLower: false,
-      // the map tile URL can be generated from a function
-      url: function (x, y, zoom) {
-        var service = 'NWS_Observations';
-        var observation = 'radar_base_reflectivity';
-        // get data from NOAA
-        var baseUrl = 'https://idpgis.ncep.noaa.gov/arcgis/rest/services/' + service + '/' + observation + '/MapServer/export';
-
-        // Get the bounding box of the tile in the desired projection
-        var bb = this.gcsTileBounds({x: x, y: y, level: zoom}, projection);
-        // make a string which the WMS server requires for the bounding box
-        var bbSpec = bb.left + ',' + bb.bottom + ',' + bb.right + ',' + bb.top;
-
-        // Set the WMS server parameters
-        var params = {
-          transparent: true,
-          format: 'png32',
-          bbox: bbSpec,
-          bboxSR: projection.split(':')[1],
-          imageSR: projection.split(':')[1],
-          size: '256,256',
-          layers: 'show:3',
-          f: 'image'
-        }
-        // construct the url for a tile.  We can use jQuery's $.param function.
-        var url =  baseUrl + '?' + $.param(params);
-        return url;
-      }
+      // the map tile URL is generated from a function
+      url: getWMSURL
     });
   +codeblock_test('map has two osm layers, one from a WMS server', [
       'map.layers().length === 2',
       'map.layers()[0] instanceof geo.osmLayer',
       'map.layers()[1] instanceof geo.osmLayer',
-      'geo.util.isFunction(map.layers()[1].url())'
+      'geo.util.isFunction(map.layers()[1].url())',
+      /* Test that the WMS server responds with a PNG */
+      '$.ajax({url: getWMSURL.call(map.layers()[1], 3, 6, 4), dataFilter: function (resp) { return resp.substr(1, 3) == "PNG"; }})'
       ])
diff --git a/tutorials/wms/thumb.jpg b/tutorials/wms/thumb.jpg
new file mode 100755
index 0000000000..7598fbed0b
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