else path not taken on a try catch block - jestjs

Question

disclaimer: this is part of a course I am taking and a practice task. I am having quite hard time wrapping my head around the test chapter of a course I am taking. Given the following class, I have to write test to it but I see the error else path not taken on my return results; line. Which else is it talking about?
import DB from './DB';
import ErrorLogger from './ErrorLogger'; // ===> if path not taken here
class ChapterSevenJest {
constructor() {
if (!ChapterSevenJest.instance) {
ChapterSevenJest.instance = this;
}
return ChapterSevenJest.instance;
}
_db = new DB();
getData = async (gradeId, teamId) => {
let results = [];
try {
results = await this._db.getData(gradeId, teamId);
} catch (error) {
ErrorLogger.register(
error
);
}
return results; // else path not taken here
};
}
const JestPractice = new ChapterSevenJest();
export default JestPractice;
the test:
import DB from './DB';
import ErrorLogger from './ErrorLogger';
import JestPractice from './JestPractice';
describe('service', () => {
const gradeId = 11;
const teamId = 1;
let spyLogs;
beforeEach(() => {
spyLogs = jest.spyOn(ErrorLogger, 'register');
spyLogs.mockReturnValue(true);
});
afterEach(() => {
spyLogs.mockReset();
});
it('should return data ot a grade and team', async () => {
const spyDB = jest.spyOn(
DB.prototype,
'getData'
);
const stat = [
{
"score" : 100,
"rank": 2
}
]
spyDB.mockResolvedValue(stat);
const results = await JestPractice.getData(
gradeId,
teamId
);
expect(spyDB).toHaveBeenCalledWith(gradeId, teamId);
expect(results).toHaveLength(1);
expect(results[0].score).toStrictEqual(100);
expect(results[0].rank).toStrictEqual(2);
});
it('should return empty on error', async () => {
const spyDB = jest.spyOn(
DB.prototype,
'getData'
);
spyDB.mockRejectedValue('error');
const results = await JestPractice.getData(
gradeId,
teamId
);
expect(spyDB).toHaveBeenCalledWith(gradeId, teamId);
expect(results).toHaveLength(0);
expect(spyLogs).toHaveBeenCalledWith(
"error"
);
});
});

Answer 1

There is only 1 if statement which is
if (!ChapterSevenJest.instance) {
ChapterSevenJest.instance = this;
}
You need to have a test where ChapterSevenJest.instance is truthy so that the if block doesn't execute.