knex-mock-client
v3.0.2
Published
A mock client for knex which allows you to write tests with DB interactions
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knex-mock-client
A mock client for Knex which allows you to write unit tests with DB interactions with a breeze.
Installation
To use this lib, first you will have to install it:
npm i --save-dev knex-mock-client
or
yarn add --dev knex-mock-client
Example
Mocking an insert
statement
// my-cool-controller.ts
import { db } from '../common/db-setup';
export async function addUser(user: User): Promise<{ id }> {
const [insertId] = await db.insert(user).into('users');
return { id: insertId };
}
// my-cool-controller.spec.ts
import { expect } from '@jest/globals';
import { createTracker, MockClient } from 'knex-mock-client';
import { faker } from '@faker-js/faker';
import { db } from '../common/db-setup';
jest.mock('../common/db-setup', () => {
const knex = require('knex');
return {
db: knex({ client: MockClient }),
};
});
describe('my-cool-controller tests', () => {
let tracker: Tracker;
beforeAll(() => {
tracker = createTracker(db);
});
afterEach(() => {
tracker.reset();
});
it('should add new user', async () => {
const insertId = faker.number.int();
tracker.on.insert('users').response([insertId]);
const newUser = { name: 'foo bar', email: '[email protected]' };
const data = await addUser(newUser);
expect(data.id).toEqual(insertId);
const insertHistory = tracker.history.insert;
expect(insertHistory).toHaveLength(1);
expect(insertHistory[0].method).toEqual('insert');
expect(insertHistory[0].bindings).toEqual([newUser.name, newUser.email]);
});
});
Each one of on
methods (select
, insert
,update
, delete
, any
) are accepting a query matcher.
There are 3 kind of matchers:
String
- will match part of the givensql
usingString.includes
tracker.on.select('select * from users where `id`=?').response([]);
RegEx
- will match the givensql
with the given regextracker.on.update(/update users where .*/).response([]);
Function
- you can specify a custom matcher by providing a function. This function will acceptRawQuery
as an argument and should return aboolean
value.tracker.on .insert( ({ method, sql, bindings }: RawQuery) => method === 'insert' && /^insert into `users`/.test(sql) && bindings.includes('secret-token') ) .response([]);
Query handlers
You can specify the db response by calling:
response<T = any>(data: T | ((rawQuery: RawQuery) => (T | Promise<T>)))
- This will register a permanent query handler.If a value is provided, it will be returned directly. If a callback is passed, it will be called with the
RawQuery
and should return a value for the tracker to return.tracker.on.select('select * from users where `id`=?').response([{ id: 1, name: 'foo' }]);
tracker.on .select('select * from users where `id`=?') .response((rawQuery) => [{ id: 1, name: 'foo' }]);
responseOnce<T = any>(data: T | ((rawQuery: RawQuery) => (T | Promise<T>)))
- This will register a one-time query handler, which will be removed from handlers list after the first usage.If a value is provided, it will be returned directly. If a callback is passed, it will be called with the
RawQuery
and should return a value for the tracker to return.tracker.on.select('select * from users where `id`=?').responseOnce([{ id: 1, name: 'foo' }]);
tracker.on .select('select * from users where `id`=?') .responseOnce((rawQuery) => Promise.resolve([{ id: 1, name: 'foo' }]));
simulateError(errorMessage: string)
- will register a permanent failure handler for the matched querytracker.on.select('select * from users where `id`=?').simulateError('Connection lost');
simulateErrorOnce(errorMessage: string)
- will register a one-time failure handler, after the first usage it will be removed from handlers list.tracker.on.select('select * from users where `id`=?').simulateErrorOnce('Connection lost');
You can reset handlers by calling tracker.resetHandlers()
which will remove all handlers for all
query methods.
History Calls
Each db request that your app makes throughout knex
will be registered in a scoped (by query
method) history call list. It will also be registered in tracker.history.all
.
Each call is an object with the interface of RawQuery
.
interface RawQuery {
method: 'select' | 'insert' | 'update' | 'delete';
sql: string;
bindings: any[];
options: Record<string, any>;
timeout: boolean;
cancelOnTimeout: boolean;
__knexQueryUid: string;
queryContext: any;
}
Specific dialects
Some DB's (like postgress) has specific dialects, for the mockClient build the proper query you must pass the dialect
property.
db = knex({
client: MockClient,
dialect: 'pg', // can be any Knex valid dialect name.
});
const givenData = [{ id: faker.number.int() }];
tracker.on.select('table_name').response(givenData);
const data = await db('table_name').distinctOn('age');
You can reset all history calls by calling tracker.resetHistory()
.
You can reset queryHandlers
& history
by calling tracker.reset()
.
This lib got inspiration from axios-mock-adapter
api️.