test: add support for gl2d in compare pixel test routine

- warn when gl2d are ran batch
- skip over multiple subplot test on CI, see
  #980
  for details

Author: etpinard

test/image/compare_pixels_test.js

@@ -51,6 +51,7 @@ var QUEUE_WAIT = 10;
 var pattern = process.argv[2];
 var mockList = getMockList(pattern);
 var isInQueue = (process.argv[3] === '--queue');
+var isCI = process.env.CIRCLECI;
 
 if(mockList.length === 0) {
     throw new Error('No mocks found with pattern ' + pattern);
@@ -60,7 +61,19 @@ if(mockList.length === 0) {
 if(!pattern) {
     console.log('Filtering out untestable mocks:');
     mockList = mockList.filter(untestableFilter);
-    console.log('\n');
+}
+
+// gl2d have limited image-test support
+if(pattern === 'gl2d_*') {
+
+    if(!isInQueue) {
+        console.log('WARN: Running gl2d image tests in batch may lead to unwanted results\n');
+    }
+
+    if(isCI) {
+        console.log('Filtering out multiple-subplot gl2d mocks:');
+        mockList = mockList.filter(untestableGL2DonCIfilter);
+    }
 }
 
 // main
@@ -93,11 +106,30 @@ function untestableFilter(mockName) {
     return cond;
 }
 
+/* gl2d mocks that have multiple subplots
+ * can't be generated properly on CircleCI
+ * at the moment.
+ *
+ * For more info see:
+ * https://github.com/plotly/plotly.js/pull/980
+ *
+ */
+function untestableGL2DonCIfilter(mockName) {
+    var cond = [
+        'gl2d_multiple_subplots',
+        'gl2d_simple_inset',
+        'gl2d_stacked_coupled_subplots',
+        'gl2d_stacked_subplots'
+    ].indexOf(mockName) === -1;
+
+    if(!cond) console.log(' -', mockName);
+
+    return cond;
+}
+
 function runInBatch(mockList) {
     var running = 0;
 
-    // remove mapbox mocks if circle ci
-
     test('testing mocks in batch', function(t) {
         t.plan(mockList.length);