test: check replaced iff translatable comment

All translatable comments should be replaced, but nothing else.

curriculum/test/utils/extract-jsx-comments.test.js

@@ -0,0 +1,29 @@
+/* global expect */
+const extractJSXComments = require('./extract-jsx-comments');
+
+const someJSX = `<Link
+className='btn-invert'
+to='/username'
+>
+Show me my public portfolio
+{/* JSX comment */}
+</Link>
+// single line comment
+
+{/* JSX comment */}
+
+/*
+a multiline comment
+*/
+`;
+
+describe('extractJSXComments', () => {
+  it('should return an object with comment keys and count values', () => {
+    const commentCounts = {
+      'JSX comment': 2,
+      'single line comment': 1,
+      'a multiline comment': 1
+    };
+    expect(extractJSXComments(someJSX)).toEqual(commentCounts);
+  });
+});