From ce5c0e53241c131f7787844c21fc69e898aa5c17 Mon Sep 17 00:00:00 2001
From: "Simen A. W. Olsen" <so@bjerk.io>
Date: Wed, 5 Apr 2023 03:40:55 +0200
Subject: [PATCH] Allow support for extra inspectables (#206)

---
 src/middleware.ts        | 15 ++++++++++++---
 src/types.ts             |  9 +++++++++
 tests/middleware.test.ts | 13 ++++++++++++-
 3 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/src/middleware.ts b/src/middleware.ts
index d90535c..2287e21 100644
--- a/src/middleware.ts
+++ b/src/middleware.ts
@@ -1,6 +1,11 @@
-import { CleanedEnvAccessors } from './types'
+import { CleanedEnvAccessors, StrictProxyMiddlewareOptions } from './types'
 
-export const strictProxyMiddleware = <T extends object>(envObj: T, rawEnv: unknown) => {
+export const strictProxyMiddleware = <T extends object>(
+  envObj: T,
+  rawEnv: unknown,
+  options: StrictProxyMiddlewareOptions = {},
+) => {
+  const { extraInspectables = [] } = options
   const inspectables = [
     'length',
     'inspect',
@@ -29,7 +34,11 @@ export const strictProxyMiddleware = <T extends object>(envObj: T, rawEnv: unkno
       // proxy that throws crashes the entire process. This permits access on
       // the necessary properties for `console.log(envObj)`, `envObj.length`,
       // `envObj.hasOwnProperty('string')` to work.
-      if (inspectables.includes(name) || inspectSymbolStrings.includes(name.toString())) {
+      if (
+        inspectables.includes(name) ||
+        inspectSymbolStrings.includes(name.toString()) ||
+        extraInspectables.includes(name)
+      ) {
         // @ts-expect-error TS doesn't like symbol types as indexers
         return target[name]
       }
diff --git a/src/types.ts b/src/types.ts
index ebfe6c5..291adc5 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -136,3 +136,12 @@ export interface CleanOptions<T> {
    */
   reporter?: ((opts: ReporterOptions<T>) => void) | null
 }
+
+export interface StrictProxyMiddlewareOptions {
+  /**
+   * A list of extra inspectable properties to add to the middleware.
+   *
+   * This is useful if you want to add support for framework-specific values.
+   */
+  extraInspectables?: string[]
+}
diff --git a/tests/middleware.test.ts b/tests/middleware.test.ts
index c0254db..857428c 100644
--- a/tests/middleware.test.ts
+++ b/tests/middleware.test.ts
@@ -1,5 +1,5 @@
 import { cleanEnv, customCleanEnv, str } from '../src'
-import { accessorMiddleware } from '../src/middleware'
+import { accessorMiddleware, strictProxyMiddleware } from '../src/middleware'
 
 describe('customCleanEnv middleware type inference', () => {
   test('allows access to properties on the output object', () => {
@@ -158,3 +158,14 @@ describe('proxy middleware', () => {
     expect(JSON.stringify(env)).toEqual('{"FOO":"foo"}')
   })
 })
+
+describe('strictProxyMiddleware', () => {
+  test('proxy allows extra inspectables applied through options', () => {
+    const env = customCleanEnv({ FOO: 'bar' }, { FOO: str() }, (cleaned, raw) =>
+      strictProxyMiddleware(cleaned, raw, { extraInspectables: ['hello'] }),
+    )
+
+    // @ts-expect-error This invalid usage should trigger a type error
+    expect(() => env.hello).not.toThrow()
+  })
+})