Add quotemark type validation to allow early return (#4310)

src/rules/quotemarkRule.ts

@@ -37,6 +37,10 @@ interface Options {
     avoidTemplate: boolean;
 }
 
+function isQuoteMark(value: QUOTE_MARK | string): value is QUOTE_MARK {
+    return ["'", '"', "`"].indexOf(value) > -1;
+}
+
 export class Rule extends Lint.Rules.AbstractRule {
     /* tslint:disable:object-literal-sort-keys */
     public static metadata: Lint.IRuleMetadata = {
@@ -120,7 +124,7 @@ function walk(ctx: Lint.WalkContext<Options>) {
                     : options.quoteMark;
             const actualQuoteMark = sourceFile.text[node.end - 1];
 
-            if (actualQuoteMark === expectedQuoteMark) {
+            if (actualQuoteMark === expectedQuoteMark || !isQuoteMark(actualQuoteMark)) {
                 return;
             }
 

test/rules/quotemark/double/test.ts.fix

@@ -4,6 +4,7 @@ var singleWithinDouble = "'singleWithinDouble'";
 var doubleWithinSingle = "\"doubleWithinSingle\"";
 var tabNewlineWithinSingle = "tab\tNewline\nWithinSingle";
 "escaped'quotemark";
+var unbalancedSingle = ('a)
 
 // "avoid-template" option is not set.
 `foo`;

test/rules/quotemark/double/test.ts.lint

@@ -8,6 +8,7 @@ var tabNewlineWithinSingle = 'tab\tNewline\nWithinSingle';
                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~  [' should be "]
 'escaped\'quotemark';
 ~~~~~~~~~~~~~~~~~~~~ [' should be "]
+var unbalancedSingle = ('a)
 
 // "avoid-template" option is not set.
 `foo`;