FIX: word boundary regex (\b) not working in Unicode languages. (#9163)

test/javascripts/lib/highlight-search-test.js.es6

@@ -0,0 +1,48 @@
+import highlightSearch, { CLASS_NAME } from "discourse/lib/highlight-search";
+import { fixture } from "helpers/qunit-helpers";
+
+QUnit.module("lib:highlight-search");
+
+QUnit.test("highlighting text", assert => {
+  fixture().html(
+    `
+    <p>This is some text to highlight</p>
+    `
+  );
+
+  highlightSearch(fixture(), "some text");
+
+  const terms = [];
+
+  fixture(`.${CLASS_NAME}`).each((_, elem) => {
+    terms.push(elem.textContent);
+  });
+
+  assert.equal(
+    terms.join(" "),
+    "some text",
+    "it should highlight the terms correctly"
+  );
+});
+
+QUnit.test("highlighting unicode text", assert => {
+  fixture().html(
+    `
+    <p>This is some தமிழ் and русский text to highlight</p>
+    `
+  );
+
+  highlightSearch(fixture(), "தமிழ் русский");
+
+  const terms = [];
+
+  fixture(`.${CLASS_NAME}`).each((_, elem) => {
+    terms.push(elem.textContent);
+  });
+
+  assert.equal(
+    terms.join(" "),
+    "தமிழ் русский",
+    "it should highlight the terms correctly"
+  );
+});