test: tests for paginate helper

Author: carlos3g

package.json

@@ -57,6 +57,7 @@
     "pug": "^3.0.3",
     "reflect-metadata": "^0.2.0",
     "rxjs": "^7.8.1",
+    "type-fest": "^4.25.0",
     "uuid": "^9.0.1"
   },
   "devDependencies": {
@@ -95,7 +96,6 @@
     "ts-loader": "^9.4.3",
     "ts-node": "^10.9.1",
     "tsconfig-paths": "^4.2.0",
-    "type-fest": "^4.25.0",
     "typescript": "^5.1.3"
   },
   "prisma": {

pnpm-lock.yaml

@@ -1,4 +1,11 @@
-import { calcSkip, getMeta } from '@app/lib/prisma/helpers/pagination';
+import { calcSkip, getMeta, paginate } from '@app/lib/prisma/helpers/pagination';
+import type { ModelDelegates } from '@app/lib/prisma/types';
+import type { ValueOf } from 'type-fest';
+
+const makeModelMock = () => ({
+  count: jest.fn(),
+  findMany: jest.fn(),
+});
 
 describe('calcSkip', () => {
   it('should return 0 when page is 1', () => {
@@ -82,3 +89,92 @@ describe('getMeta', () => {
     });
   });
 });
+
+describe('paginate', () => {
+  let model: {
+    count: jest.Mock;
+    findMany: jest.Mock;
+  };
+
+  beforeEach(() => {
+    model = makeModelMock();
+  });
+
+  it('should calculate skip correctly', () => {
+    expect(calcSkip(1, 20)).toBe(0);
+    expect(calcSkip(2, 20)).toBe(20);
+    expect(calcSkip(3, 20)).toBe(40);
+  });
+
+  it('should calculate metadata correctly', () => {
+    const meta = getMeta(100, 2, 20);
+    expect(meta).toEqual({
+      total: 100,
+      lastPage: 5,
+      currentPage: 2,
+      perPage: 20,
+      prev: 1,
+      next: 3,
+    });
+  });
+
+  it('should paginate results correctly', async () => {
+    model.count.mockResolvedValue(100);
+    model.findMany.mockResolvedValue(['item1', 'item2']);
+
+    const result = await paginate(model as unknown as ValueOf<ModelDelegates>, {}, { page: 2, perPage: 20 });
+
+    expect(model.count).toHaveBeenCalledWith({ where: undefined });
+    expect(model.findMany).toHaveBeenCalledWith({
+      take: 20,
+      skip: 20,
+    });
+    expect(result).toEqual({
+      data: ['item1', 'item2'],
+      meta: {
+        total: 100,
+        lastPage: 5,
+        currentPage: 2,
+        perPage: 20,
+        prev: 1,
+        next: 3,
+      },
+    });
+  });
+
+  it('should handle default values for page and perPage', async () => {
+    model.count.mockResolvedValue(50);
+    model.findMany.mockResolvedValue(['item1', 'item2', 'item3', 'item4']);
+
+    const result = await paginate(model as unknown as ValueOf<ModelDelegates>, {}, {});
+
+    expect(result.meta.currentPage).toBe(1);
+    expect(result.meta.perPage).toBe(20);
+  });
+
+  it('should handle pagination when there is only one page', async () => {
+    model.count.mockResolvedValue(10);
+    model.findMany.mockResolvedValue(['item1', 'item2']);
+
+    const result = await paginate(model as unknown as ValueOf<ModelDelegates>, {}, { page: 1, perPage: 10 });
+
+    expect(result.meta).toEqual({
+      total: 10,
+      lastPage: 1,
+      currentPage: 1,
+      perPage: 10,
+      prev: null,
+      next: null,
+    });
+  });
+
+  it('should return empty data if no items found', async () => {
+    model.count.mockResolvedValue(0);
+    model.findMany.mockResolvedValue([]);
+
+    const result = await paginate(model as unknown as ValueOf<ModelDelegates>, {}, { page: 1, perPage: 10 });
+
+    expect(result.data).toEqual([]);
+    expect(result.meta.total).toBe(0);
+  });
+});

src/lib/prisma/helpers/pagination.spec.ts

@@ -1,6 +1,7 @@
 /* eslint-disable @typescript-eslint/ban-ts-comment */
 /* eslint-disable @typescript-eslint/no-unsafe-assignment */
-import type { Prisma, PrismaClient } from '@prisma/client';
+import type { ModelDelegates } from '@app/lib/prisma/types';
+import type { Prisma } from '@prisma/client';
 
 export interface PaginatedResult<T> {
   data: T[];
@@ -14,11 +15,6 @@ export interface PaginatedResult<T> {
   };
 }
 
-// see: https://github.com/prisma/prisma/issues/6980
-type ModelDelegates = {
-  [K in Prisma.ModelName]: PrismaClient[Uncapitalize<K>];
-};
-
 export type PaginateOptions = { page?: number; perPage?: number };
 export type PaginateFunction = <T, K extends Prisma.ModelName>(
   model: ModelDelegates[K],

src/lib/prisma/helpers/pagination.ts

@@ -0,0 +1,6 @@
+import type { Prisma, PrismaClient } from '@prisma/client';
+
+// see: https://github.com/prisma/prisma/issues/6980
+export type ModelDelegates = {
+  [K in Prisma.ModelName]: PrismaClient[Uncapitalize<K>];
+};