refactor: make cwd required in EngineConfig (#18052)

It was already de facto required for `LibraryEngine` (`BinaryEngine`
did handle the missing `cwd`) but it was marked as optional in the
`EngineConfig` interface. There were two places which would break if
`cwd` wasn't passed to the engine constructor:

1. In `DefaultLibraryLoader` it was assumed that `config.cwd` was
   non-nullable.  TypeScript did not raise an error because another
   element in the same array was `any`, which caused the whole array
   to silently be `any[]` and assignable to `string[]`. Fixing that
   issue immediately uncovered a type error in `this.config.cwd` array
   item.

2. In `LibraryEngine` `this.config.cwd` was forcibly converted to a
   non-nullable string with the `!` operator and passed to the query
   engine constructor. This would trigger an error on the Rust side.

Tests in `LibraryEngine.test.ts` didn't have a `cwd` in the engine
config, but they still passed because they used a mock engine and
library loader which didn't rely on `cwd`. They would fail with real
implementations though.

A missing `logEmitter` was added along the way in
`BinaryEngine.test.ts`. TypeScript did flag that as an error, but we
don't type check the old tests.

Ref: https://github.com/prisma/client-planning/issues/103

packages/client/src/__tests__/binaryEngine.test.ts

@@ -1,5 +1,6 @@
 import { BinaryEngine } from '@prisma/engine-core'
 import { ClientEngineType, getClientEngineType } from '@prisma/internals'
+import { EventEmitter } from 'events'
 import path from 'path'
 
 describe('BinaryEngine', () => {
@@ -16,6 +17,8 @@ describe('BinaryEngine', () => {
         datamodelPath: path.join(__dirname, './runtime-tests/blog/schema.prisma'),
         tracingConfig: { enabled: false, middleware: false },
         env: {},
+        cwd: process.cwd(),
+        logEmitter: new EventEmitter(),
       })
       await engine.start()
     } catch (e) {

packages/engine-core/src/__tests__/LibraryEngine.test.ts

@@ -43,6 +43,7 @@ function setupMockLibraryEngine() {
         middleware: false,
       },
       env: {},
+      cwd: process.cwd(),
     },
     loader,
   )
@@ -109,6 +110,7 @@ test('responds to initialization error with PrismaClientInitializationError', as
         middleware: false,
       },
       env: {},
+      cwd: process.cwd(),
     },
     loader,
   )

packages/engine-core/src/binary/BinaryEngine.ts

@@ -256,8 +256,8 @@ You may have to run ${chalk.greenBright('prisma generate')} for your changes to
     }
   }
 
-  private resolveCwd(cwd?: string): string {
-    if (cwd && fs.existsSync(cwd) && fs.lstatSync(cwd).isDirectory()) {
+  private resolveCwd(cwd: string): string {
+    if (fs.existsSync(cwd) && fs.lstatSync(cwd).isDirectory()) {
       return cwd
     }
 

packages/engine-core/src/common/Engine.ts

@@ -102,7 +102,7 @@ export interface DatasourceOverwrite {
 }
 
 export interface EngineConfig {
-  cwd?: string
+  cwd: string
   dirname?: string
   datamodelPath: string
   enableDebugLogs?: boolean

packages/engine-core/src/library/DefaultLibraryLoader.ts

@@ -144,7 +144,7 @@ Read more about deploying Prisma Client: https://pris.ly/d/client-generator`
       return { enginePath, searchedLocations }
     }
 
-    const dirname = eval('__dirname')
+    const dirname = eval('__dirname') as string
     const searchLocations: string[] = [
       // TODO: why hardcoded path? why not look for .prisma/client upwards?
       path.resolve(dirname, '../../../.prisma/client'), // Dot Prisma Path

packages/engine-core/src/library/LibraryEngine.ts

@@ -256,7 +256,7 @@ You may have to run ${chalk.greenBright('prisma generate')} for your changes to
             ignoreEnvVarErrors: true,
             datasourceOverrides: this.datasourceOverrides,
             logLevel: this.logLevel,
-            configDir: this.config.cwd!,
+            configDir: this.config.cwd,
           },
           (log) => {
             weakThis.deref()?.logger(log)