no-invalid-template-strings: fix for escaped template expressions (#3116)

Author: aervin_

src/rules/noInvalidTemplateStringsRule.ts

@@ -50,10 +50,28 @@ function walk(ctx: Lint.WalkContext<void>) {
  });
 
  function check(node: ts.StringLiteral): void {
- const idx = node.text.search(/\$\{/);
- if (idx !== -1) {
+ /**
+ * Finds instances of '${'
+ */
+ const findTemplateString = new RegExp(/\$\{/);
+ 
+ const index = node.text.search(findTemplateString);
+ if (index !== -1) {
+ /**
+ * Support for ignoring case: '\${template-expression}'
+ */
+ const unescapedText = node.getFullText();
+ const preceedingCharacter = unescapedText.substr(unescapedText.search(findTemplateString) - 1, 1);
+ if (isBackslash(preceedingCharacter)) {
+ return;
+ }
+
  const textStart = node.getStart() + 1;
- ctx.addFailureAt(textStart + idx, 2, Rule.FAILURE_STRING);
+ ctx.addFailureAt(textStart + index, 2, Rule.FAILURE_STRING);
  }
  }
 }
+
+function isBackslash(character: string): boolean {
+ return character === "\\";
+}

test/rules/no-invalid-template-strings/test.ts.lint

@@ -1,3 +1,9 @@
+new (Tab.mixins.Controlled('MemberComments',Tab.mixins.Templated('<div mbr-comment-tab=\${which}></div>',Tab.mixins.AlwaysHasData())))
+
+new (Tab.mixins.Controlled('MemberComments',Tab.mixins.Templated('<div mbr-comment-tab=\${which}></div>',Tab.mixins.AlwaysHasData('\${which}'))))
+
+new (Tab.mixins.Controlled('MemberComments',Tab.mixins.Templated('<div mbr-comment-tab=\\\\\\${which}></div>',Tab.mixins.AlwaysHasData())))
+
 "One plus one is ${1 + 1}.";
  ~~ [0]