From 315531ad53d0625e9c8230a1b27c8390e754edfb Mon Sep 17 00:00:00 2001
From: Alex McHardy <alexmchardy@gmail.com>
Date: Tue, 13 Jul 2021 02:55:34 -0600
Subject: [PATCH] fix: Respect user-defined prefix/suffix when looking for
 default NS (#1248)

* fix: Respect user-defined prefix/suffix when looking for default NS

* Add test

Co-authored-by: Isaac Hinman <isaac@isaachinman.com>
---
 src/config/createConfig.test.ts | 22 +++++++++++++++++++---
 src/config/createConfig.ts      |  4 +++-
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/config/createConfig.test.ts b/src/config/createConfig.test.ts
index 966a3147..bb6c9f04 100644
--- a/src/config/createConfig.test.ts
+++ b/src/config/createConfig.test.ts
@@ -116,15 +116,31 @@ describe('createConfig', () => {
       })
     })
 
-    describe('when filesystem is missing defaultNS', () => {
-      it('throws an error', () => {
+    describe('defaultNS validation', () => {
+      it('when filesystem is missing defaultNS throws an error', () => {
         (fs.existsSync as jest.Mock).mockReturnValueOnce(false)
 
         const config = createConfig.bind(null, {
           lng: 'en',
-        } as any)
+        } as UserConfig)
+
+        expect(config).toThrow('Default namespace not found at public/locales/en/common.json')
+      })
+
+      it('uses user provided prefix/suffix with localeStructure', () => {
+        (fs.existsSync as jest.Mock).mockReturnValueOnce(false)
+
+        const config = createConfig.bind(null, {
+          interpolation: {
+            prefix: '^^',
+            suffix: '$$',
+          },
+          lng: 'en',
+          localeStructure: '^^lng$$/^^ns$$',
+        } as UserConfig)
 
         expect(config).toThrow('Default namespace not found at public/locales/en/common.json')
+        expect(fs.existsSync).toHaveBeenCalledWith('public/locales/en/common.json')
       })
     })
 
diff --git a/src/config/createConfig.ts b/src/config/createConfig.ts
index 46fc0411..5c72a312 100644
--- a/src/config/createConfig.ts
+++ b/src/config/createConfig.ts
@@ -55,7 +55,9 @@ export const createConfig = (userConfig: UserConfig): InternalConfig => {
       // https://github.com/isaachinman/next-i18next/issues/358
       //
       if (typeof defaultNS === 'string' && typeof lng !== 'undefined') {
-        const defaultLocaleStructure = localeStructure.replace('{{lng}}', lng).replace('{{ns}}', defaultNS)
+        const prefix = userConfig?.interpolation?.prefix ?? '{{'
+        const suffix = userConfig?.interpolation?.suffix ?? '}}'
+        const defaultLocaleStructure = localeStructure.replace(`${prefix}lng${suffix}`, lng).replace(`${prefix}ns${suffix}`, defaultNS)
         const defaultFile = `/${defaultLocaleStructure}.${localeExtension}`
         const defaultNSPath = path.join(localePath, defaultFile)
         const defaultNSExists = fs.existsSync(defaultNSPath)