Throw parse ex on invalid quoted selector

Author: jhy

src/main/java/org/jsoup/select/Evaluator.java

@@ -426,8 +426,10 @@ public AttributeKeyPair(String key, String value) {
             this.key = normalize(key);
             boolean quoted = value.startsWith("'") && value.endsWith("'")
                 || value.startsWith("\"") && value.endsWith("\"");
-            if (quoted)
+            if (quoted) {
+                Validate.isTrue(value.length() > 1, "Quoted value must have content");
                 value = value.substring(1, value.length() - 1);
+            }
 
             this.value = lowerCase(value); // case-insensitive match
         }

src/test/java/org/jsoup/select/SelectorTest.java

@@ -1768,7 +1768,7 @@ public void testAncestorChain() {
         assertSelectedIds(doc.select("div[data*='']"), "1", "2", "3");
     }
 
-    @Test void parseExceptionOnEmptyUrl() {
+    @Test void parseExceptionOnEmptyAbsKey() {
         // was previously firing at match time, not eval time
         String q = "[abs:!=]";
         boolean threw = false;
@@ -1781,4 +1781,17 @@ public void testAncestorChain() {
         assertTrue(threw);
     }
 
+    @Test void parseExceptionOnEmptyKeyVal() {
+        // was previously firing at match time, not eval time
+        String q = "[\"=\"]";
+        boolean threw = false;
+        try {
+            Evaluator e = Selector.evaluatorOf(q);
+        } catch (Selector.SelectorParseException ex) {
+            threw = true;
+            assertEquals("Quoted value must have content", ex.getMessage());
+        }
+        assertTrue(threw);
+    }
+
 }