fix: Decode HTML entities in the test output (#111)

packages/learn/utils/decodeHTMLEntities.js

@@ -0,0 +1,27 @@
+/*
+ * Converts HTML entity codes in a string to the characters they represent.
+ *
+ * Example:
+ * `decodeHTMLEntities('Beets & carrots');`
+ * will return "Beets & carrots".
+ *
+ * The regex makes sure we only replace the HTML entities in the string.
+ * For example, the regex would match "<" as well as ":".
+ * The decoding works by setting the innerHTML of a dummy element and then
+ * retrieving the innerText. Per the spec, innerText is a property that
+ * represents the "rendered" text content of an element.
+ *
+ * See:
+ * https://developer.mozilla.org/en-US/docs/Web/API/Node/innerText
+ * https://developer.mozilla.org/en-US/docs/Glossary/Entity
+ *
+ */
+const decodeHTMLEntities = str => {
+  const el = document.createElement('div');
+  return str.replace(/\&[#0-9a-z]+;/gi, enc => {
+    el.innerHTML = enc;
+    return el.innerText;
+  });
+};
+
+export default decodeHTMLEntities;