Fix/jest memory leaks

[jpb06]

Huge leaking Issue with backend tests right there :

 PASS  src/modules/books/book/books.spec.ts (7.415 s, 208 MB heap size)
 PASS  src/modules/books/author/authors.spec.ts (265 MB heap size)
 PASS  src/modules/books/categories/categories.spec.ts (259 MB heap size)
 PASS  src/modules/books/book/books.service.test.ts (299 MB heap size)
 PASS  src/modules/books/categories/categories.service.test.ts (335 MB heap size)
 PASS  src/modules/books/author/authors.service.test.ts (355 MB heap size)
 PASS  src/modules/users/user/users.spec.ts (315 MB heap size)
 PASS  src/modules/users/auth/auth.service.test.ts (344 MB heap size)
 PASS  src/filters/fk-exception.filter.test.ts (366 MB heap size)
 PASS  src/modules/books/book/books.controller.test.ts (410 MB heap size)
 PASS  src/filters/fk-deletion-exception.filter.test.ts (420 MB heap size)
 PASS  src/modules/users/user/users.controller.test.ts (458 MB heap size)
 PASS  src/modules/users/auth/strategies/local.strategy.test.ts (362 MB heap size)
 PASS  src/pipes/validation.pipe.test.ts (385 MB heap size)
 PASS  src/modules/database/database.service.test.ts (419 MB heap size)
 PASS  src/bootstrap.test.ts (471 MB heap size)
 PASS  src/modules/users/user/users.service.test.ts (503 MB heap size)
 PASS  src/pipes/number-array.pipe.test.ts (513 MB heap size)
 PASS  src/main.test.ts (548 MB heap size)

ts-jest

kulshekhar/ts-jest#1967

 PASS  src/modules/books/book/books.spec.ts (5.07 s, 126 MB heap size)
 PASS  src/modules/books/author/authors.spec.ts (175 MB heap size)
 PASS  src/modules/books/categories/categories.spec.ts (232 MB heap size)
 PASS  src/modules/books/book/books.service.test.ts (161 MB heap size)
 PASS  src/modules/books/categories/categories.service.test.ts (183 MB heap size)
 PASS  src/modules/books/author/authors.service.test.ts (204 MB heap size)
 PASS  src/modules/users/user/users.spec.ts (241 MB heap size)
 PASS  src/modules/users/auth/auth.service.test.ts (268 MB heap size)
 PASS  src/filters/fk-exception.filter.test.ts (287 MB heap size)
 PASS  src/modules/books/book/books.controller.test.ts (322 MB heap size)
 PASS  src/filters/fk-deletion-exception.filter.test.ts (340 MB heap size)
 PASS  src/modules/users/user/users.controller.test.ts (363 MB heap size)
 PASS  src/modules/users/auth/strategies/local.strategy.test.ts (389 MB heap size)
 PASS  src/pipes/validation.pipe.test.ts (412 MB heap size)
 PASS  src/modules/database/database.service.test.ts (285 MB heap size)
 PASS  src/bootstrap.test.ts (341 MB heap size)
 PASS  src/modules/users/user/users.service.test.ts (364 MB heap size)
 PASS  src/pipes/number-array.pipe.test.ts (373 MB heap size)
 PASS  src/main.test.ts (358 MB heap size)

node > v16.10

jestjs/jest#11956

Switching to v16.10.0 helps a lot (from v16.13.0) :

 PASS  src/modules/books/book/books.spec.ts (119 MB heap size)
 PASS  src/modules/books/author/authors.spec.ts (159 MB heap size)
 PASS  src/modules/books/categories/categories.spec.ts (193 MB heap size)
 PASS  src/modules/books/book/books.service.test.ts (206 MB heap size)
 PASS  src/modules/books/categories/categories.service.test.ts (217 MB heap size)
 PASS  src/modules/books/author/authors.service.test.ts (126 MB heap size)
 PASS  src/modules/users/user/users.spec.ts (145 MB heap size)
 PASS  src/modules/users/auth/auth.service.test.ts (125 MB heap size)
 PASS  src/filters/fk-exception.filter.test.ts (139 MB heap size)
 PASS  src/modules/books/book/books.controller.test.ts (173 MB heap size)
 PASS  src/filters/fk-deletion-exception.filter.test.ts (172 MB heap size)
 PASS  src/modules/users/user/users.controller.test.ts (193 MB heap size)
 PASS  src/modules/users/auth/strategies/local.strategy.test.ts (143 MB heap size)
 PASS  src/pipes/validation.pipe.test.ts (149 MB heap size)
 PASS  src/modules/database/database.service.test.ts (175 MB heap size)
 PASS  src/bootstrap.test.ts (203 MB heap size)
 PASS  src/modules/users/user/users.service.test.ts (147 MB heap size)
 PASS  src/pipes/number-array.pipe.test.ts (154 MB heap size)
 PASS  src/main.test.ts (183 MB heap size)

What did NOT help:

• add an afterEach/afterAll to close/flushlogs and garbage collect the INestApplication instance
• explicit garbage collector calls in afterAll
• moving prisma artifacts outside of node_modules
• moving deepmocks inside tests

[sonarcloud]

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