fix: use dynamic import() to load Prisma client (fixes #22)

src/contest.test.ts

@@ -1,3 +1,5 @@
+import { resolve } from 'node:path';
+import { pathToFileURL } from 'node:url';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 import {
   type PrismaClient as PrismaClientStub,
@@ -19,9 +21,9 @@ const makeContext = async (
     | 'transactionPending'
     | 'transactionStarted'
     | 'transactionEnded' = 'transactionPending',
-): Promise<[ReturnType<typeof createContext>, PrismaClientStub]> => {
-  const context = createContext({
-    clientPath: '../test/prisma-client-stub.js',
+): Promise<[Awaited<ReturnType<typeof createContext>>, PrismaClientStub]> => {
+  const context = await createContext({
+    clientPath: './test/prisma-client-stub.js',
     databaseUrl: 'postgres://fake',
     log: ['query'],
     transactionOptions: { timeout: 123 },
@@ -53,6 +55,24 @@ describe('createContext', () => {
     await ctx.teardown();
   });
 
+  it('accepts an absolute file:// URL as clientPath', async () => {
+    vi.stubEnv('DATABASE_URL', 'postgres://fake');
+    const fileUrl = pathToFileURL(resolve('./test/prisma-client-stub.js')).href;
+    const ctx = await createContext({
+      clientPath: fileUrl,
+      databaseUrl: 'postgres://fake',
+      log: ['query'],
+      transactionOptions: { timeout: 123 },
+    });
+    await ctx.setup();
+
+    expect(PrismaPgMock).toHaveBeenCalledWith({
+      connectionString: 'postgres://fake',
+    });
+
+    await ctx.teardown();
+  });
+
   it('throws when client is accessed outside of a test transaction', async () => {
     const [transactionPendingContext] = await makeContext('transactionPending');
     const [transactionEndedContext] = await makeContext('transactionEnded');

src/context.ts

@@ -1,20 +1,19 @@
-import { createRequire } from 'node:module';
+import { isAbsolute, resolve } from 'node:path';
+import { pathToFileURL } from 'node:url';
 import { PrismaPg } from '@prisma/adapter-pg';
 import type {
   PrismaClientLike,
   PrismaPostgresEnvironmentOptions,
 } from './dts/index.js';
 
-const require = createRequire(import.meta.url);
-
 /**
  * Creates the test context used by the `prisma-postgres` Vitest environment.
  *
  * @param options PrismaPostgresEnvironmentOptions
  * @returns The test context object used by both the Vitest environment and the
  * user's Prisma client mock.
  */
-export function createContext(options: PrismaPostgresEnvironmentOptions) {
+export async function createContext(options: PrismaPostgresEnvironmentOptions) {
   let savePointCounter = 0;
 
   /**
@@ -31,7 +30,17 @@ export function createContext(options: PrismaPostgresEnvironmentOptions) {
    */
   let internalEndTestTransaction: (() => void) | null = null;
 
-  const { PrismaClient } = require(options.clientPath);
+  // Normalize clientPath so relative/absolute filesystem paths resolve against
+  // the consuming project's CWD instead of this module's location. Leave bare
+  // module specifiers (e.g. '@prisma/client') and existing file:// URLs
+  // untouched so ESM resolution handles them as-is.
+  const isPathLike =
+    options.clientPath.startsWith('.') || isAbsolute(options.clientPath);
+  const clientImportPath = isPathLike
+    ? pathToFileURL(resolve(options.clientPath)).href
+    : options.clientPath;
+
+  const { PrismaClient } = await import(clientImportPath);
   const originalClient: PrismaClientLike = new PrismaClient({
     adapter: new PrismaPg({ connectionString: process.env.DATABASE_URL }),
     log: options.log,

src/index.test.ts

@@ -24,7 +24,7 @@ import environment from '../src/index.js';
 describe('prisma-postgres environment', () => {
   const global: any = {};
   const options = {
-    clientPath: '../test/prisma-client-stub.js',
+    clientPath: './test/prisma-client-stub.js',
   };
 
   beforeEach(() => {

src/index.ts

@@ -17,7 +17,7 @@ const environment: Environment = {
       throw new Error('no DATABASE_URL defined!');
     }
 
-    const ctx = createContext(options);
+    const ctx = await createContext(options);
     await ctx.setup();
 
     // make context available globally for setupFiles.