Rename the file and add the first test.

src/load-student.js → src/load-student.spec.js

@@ -7,3 +7,11 @@ export const loadStudent = ({ studentId }) => {
   }
   return cache[studentId];
 };
+
+describe('Load a student', () => {
+  it('from the cache', () => {
+    cache[42] = 'student 42';
+    const student = loadStudent({ studentId: 42 });
+    assertThat(student, equalTo('student 42'));
+  });
+});