Add unit tests (#10)

* Flatten submodule structure

* Initial "findRandom" test suite

* findManyRandom tests

* Add to CI

* Add back "packageManager" field in package.json

Discovered that this is used in github actions

.github/workflows/CI.yml

@@ -47,12 +47,11 @@ jobs:
       - name: Generate prisma schema
         run: npx prisma generate
 
-      # If we ever add ESLint, uncomment this
-      # - name: Run ESLint
-      #   run: pnpm lint
-
       - name: Build
         run: pnpm build
 
+      - name: Test
+        run: pnpm test
+
       - name: Run Prettier
         run: pnpm format --list-different

example/db.test.ts

@@ -0,0 +1,75 @@
+import { prisma } from './db';
+import { assert, beforeEach, test } from 'vitest';
+
+const POPULATION = 1000;
+const NUM_TRIALS = 10000;
+
+const STD_RATIO = 3.4641016151377544;
+
+beforeEach(async () => {
+  await prisma.user.deleteMany();
+  for (let i = 1; i <= POPULATION; ++i) {
+    await prisma.user.create({
+      data: {
+        firstName: 'User' + (i % 2),
+        lastName: i.toString(),
+      },
+    });
+  }
+});
+
+test('empty findRandom', async () => {
+  await prisma.user.deleteMany();
+  const user = await prisma.user.findRandom();
+  assert.isNull(user);
+});
+
+test('empty findManyRandom', async () => {
+  await prisma.user.deleteMany();
+  const users = await prisma.user.findManyRandom(10000);
+  assert.isEmpty(users);
+});
+
+test('findRandom distribution', async () => {
+  const results: Record<string, number> = {};
+  let sum = 0;
+  for (let i = 0; i < NUM_TRIALS; ++i) {
+    const user = await prisma.user.findRandom();
+    if (!user) assert.fail('findRandom returned null');
+    sum += +user.lastName;
+    results[user.lastName] = (results[user.lastName] ?? 0) + 1;
+  }
+
+  // Make sure that every user was hit
+  for (let i = 1; i <= POPULATION; ++i) {
+    assert.property(results, i.toString());
+  }
+
+  const mean = sum / NUM_TRIALS;
+  const std = Math.sqrt(
+    Object.keys(results)
+      .map((idx) => results[idx] * Math.pow(+idx - mean, 2))
+      .reduce((a, b) => a + b) / NUM_TRIALS,
+  );
+  console.log({ mean, std });
+
+  // Expected (based on a standard uniform distribution)
+  const expectedMean = POPULATION / 2;
+  const expectedStd = POPULATION / STD_RATIO;
+
+  assert.isBelow(mean, expectedMean * 1.02);
+  assert.isAbove(mean, expectedMean * 0.98);
+
+  assert.isBelow(std, expectedStd * 1.01);
+  assert.isAbove(std, expectedStd * 0.99);
+});
+
+test('findManyRandom', async () => {
+  const users1 = await prisma.user.findManyRandom(POPULATION, {
+    where: { firstName: 'User0' },
+  });
+  assert.lengthOf(users1, POPULATION / 2);
+
+  const users2 = await prisma.user.findManyRandom(POPULATION + 10009);
+  assert.lengthOf(users2, POPULATION);
+});

example/db.ts

@@ -0,0 +1,4 @@
+import { PrismaClient } from '@prisma/client';
+import prismaRandom from '../dist';
+
+export const prisma = new PrismaClient().$extends(prismaRandom());

example/index.ts

@@ -1,4 +1,20 @@
-import { PrismaClient } from '@prisma/client';
-import prismaRandom from '../dist';
+import { prisma } from './db';
 
-export const prisma = new PrismaClient().$extends(prismaRandom());
+const main = async () => {
+  const user = await prisma.user.findRandom();
+
+  const post = await prisma.post.findManyRandom(10, {
+    select: { id: true, title: true },
+    where: {
+      OR: [
+        { title: { contains: 'prisma' } },
+        { content: { contains: 'prisma' } },
+      ],
+      published: true,
+    },
+  });
+
+  console.log({ user, post });
+};
+
+main();