I have a simple function to fetch values from the Postgres database. I need to test the method by mocking the database. I have tried various approaches provided but none of them worked. Some errors always occur. I have tried the below solutions:
Below are my files.
db.ts
import { Pool } from 'pg'
const pool = new Pool({
user: `${process.env.POSTGRES_USER}`,
database: `${process.env.POSTGRES_DB}`,
password: `${process.env.POSTGRES_PASSWORD}`,
port: `${process.env.POSTGRES_PORT}`,
host: `${process.env.POSTGRES_HOST}`,
})
export default pool;
fetch.ts
import pool from "./db";
import {SO} from "./s2l";
export async function fetch(code: string): Promise<SO[]>{
let socalls: SO[] =[]
const sql = 'Select sg.v1,sg.v2,sg.v3,sg.v4 from table1 sg where code = $1 and sg.r_code not in(\'ABC\', \'XYZ\', \'PQR\') order by sg.datetime asc'
const values = [code]
const client = await pool.connect()
await client.query(sql, values).then(res => {
const data = res.rows;
let so
data.forEach(row => {
so ={
service: {
code: row["v1"]
},
rCode: row["v2"],
dVo: row["v3"],
aVo: row["v4"],
};
socalls.push(so)
});
}).catch(e => console.error(e))
.then(() => client.release())
return Promise.all(socalls);
}
Also, I need to pass the list in the query dynamically.
The below approach worked for me
fetch.test.ts
import { fetch } from "./fetch";
import pool from "./db";
describe("Test fetch of so calls from database", () => {
afterAll(() => {
jest.resetAllMocks();
});
it("Happy case", async () => {
(pool as any).connect = jest.fn().mockReturnThis();
(pool as any).query = jest.fn().mockReturnThis();
(pool as any).release = jest.fn().mockReturnThis();
(pool as any).query.mockResolvedValueOnce({
rows: [
{
v2: "EHRBFK76TGSMD",
v3: "355GG",
v4: "355GG",
v1: "Q923892GT",
},
],
});
const result = await fetchSiteCalls("Y2K");
expect(result).toEqual([
{
rCode: "EHRBFK76TGSMD",
dVo: "355GG",
aVo: "355GG",
service: { code: "Q923892GT" },
},
]);
});
});
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