Tests for 2991

Author: Olivier Nicodemi

packages/test-data/css/_main/css-3.css

@@ -136,8 +136,6 @@ body > .shadow {
   symbols: ‣;
   suffix: " ";
 }
-@-ms-viewport {
-}
 @unknown foo 42 (bar) {
   x {
     y: z;

packages/test-data/less/_main/import-reference-issues.less

@@ -5,6 +5,7 @@
 // * #2716 - A file imported by reference and then normally - multiple imports should be independent
 // * #1968 - When using an @import (reference), mixins that contain an & selector get added to the compiled output improperly
 // * #2162 - Cannot put import by reference inside of a mixin (also doubles #1896)
+// * #2991 - Empty @media queries generated through line comments when compiling less file with (reference)
 
 // #1878: extend inside referenced file should not extend outside selectors
 @import (reference) "import-reference-issues/global-scope-import.less";
@@ -48,3 +49,5 @@ show-all-content {
 call-mixin-with-import-by-reference-inside {
   .mixin-with-import-by-reference-inside();
 }
+
+@import (reference) "import-reference-issues/comments-2991.less";

packages/test-data/less/_main/import-reference-issues/comments-2991.less

@@ -0,0 +1,22 @@
+.referenced {
+    // line comment is enough to reproduce it
+    @media (hover) {
+        // sezam
+    }
+    // repeat to prove point
+    @media (hover) {
+        // sezam
+    }
+    // but block comment is not, huh
+    @media (hover) {
+        /* salabim */
+    }
+    // following block does not output, needs line comment
+    @media (hover) {
+        color: #000000;
+    }
+}
+// needs to be nested to fail
+@media (hover) {
+    // sezam
+}