add tests for chain selector support

Author: btamas

test/fixtures/chained-selector.css

@@ -0,0 +1,30 @@
+button {
+    --width-small: 50px;
+}
+
+button.custom {
+    --width-small: 100px;
+    --width-medium: 200px;
+    --width-large: 300px;
+    --font-size: 12px;
+}
+
+button.rounded.small {
+    width: var(--width-small);
+}
+
+button.custom.large {
+    width: var(--width-large);
+}
+
+button.rounded.custom.medium {
+    width: var(--width-medium);
+}
+
+button#id.rounded.custom.medium {
+    width: var(--width-medium);
+}
+
+button.small.pill.custom {
+    width: var(--width-small);
+}

test/fixtures/chained-selector.expected.css

@@ -0,0 +1,19 @@
+button.rounded.small {
+    width: 50px;
+}
+
+button.custom.large {
+    width: 300px;
+}
+
+button.rounded.custom.medium {
+    width: 200px;
+}
+
+button#id.rounded.custom.medium {
+    width: 200px;
+}
+
+button.small.pill.custom {
+    width: 100px;
+}

test/test.js

@@ -129,6 +129,7 @@ describe('postcss-css-variables', function() {
 
 	test('should work with `!important` variable declarations', 'important-variable-declaration');
 
+	test('should work with chained selectors', 'chained-selector');
 
 
 	describe('with at-rules', function() {