test: added test with css custom properties

Add test for CSS custom properties and fix spelling mistakes

Author: MoltenCoffee

test/duplicated-properties.js

@@ -8,7 +8,7 @@ const plugin = require('../src');
  */
 
 /**
- * Take string literals are remove newlines and extra spacing so results print
+ * Take string literals and remove newlines and extra spacing so results print
  * as expected in logs
  * @return {string} string without newlines and tabs
  */
@@ -23,7 +23,7 @@ const removeDuplicates = testFactory(
 );
 
 test(
-    'remove duplicated properties when combine selectors',
+    'remove duplicated properties when combining selectors',
     removeDuplicates,
     '.a {height: 10px; color: black;} .a {color: blue; width: 20px;}',
     '.a {height: 10px;color: blue; width: 20px;}',
@@ -54,7 +54,7 @@ const keepDuplicates = testFactory(
 );
 
 test(
-    'maintain duplicated properties when combine selectors',
+    'maintain duplicated properties when combining selectors',
     keepDuplicates,
     '.a {height: 10px; color: black;} .a {color: blue; width: 20px;}',
     '.a {height: 10px; color: black;color: blue; width: 20px;}',
@@ -86,7 +86,7 @@ const removeExactDuplicates = testFactory(
 );
 
 test(
-    'remove duplicated properties with matching values when combine selectors',
+    'remove duplicated properties with matching values with combined selectors',
     removeExactDuplicates,
     '.a {height: 10px; color: red;} .a {color: red; color: blue; width: 20px;}',
     '.a {height: 10px;color: red; color: blue; width: 20px;}',
@@ -111,3 +111,23 @@ test(
 }
 `,
 );
+
+test(
+    'remove duplicate property with matching value, allow fallback',
+    removeExactDuplicates,
+    minify`
+.a {
+  height: 10px;
+}
+.a {
+  height: 10px;
+  height: var(--linkHeight);
+}
+`,
+    minify`
+.a {
+  height: 10px;
+  height: var(--linkHeight);
+}
+`,
+);