From c0bf0fc13da70e2bde923cd1746119d2e7ac4b2f Mon Sep 17 00:00:00 2001
From: Stephen Haberman <stephen.haberman@gmail.com>
Date: Wed, 19 Jan 2022 08:41:47 -0600
Subject: [PATCH] fix: Have snakeToCamel leave existing mixed case. (#482)

Fixes #478
---
 src/case.ts        | 3 ++-
 tests/case-test.ts | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/case.ts b/src/case.ts
index 5e57b5fa7..4cd770126 100644
--- a/src/case.ts
+++ b/src/case.ts
@@ -2,12 +2,13 @@ import { Options } from './options';
 
 export function maybeSnakeToCamel(s: string, options: Pick<Options, 'snakeToCamel'>): string {
   if (options.snakeToCamel.includes('keys') && s.includes('_')) {
+    const hasLowerCase = !!s.match(/[a-z]/);
     return s
       .split('_')
       .map((word, i) => {
         if (i === 0) {
           // if first symbol is "_" then skip it
-          return word ? word[0] + word.substring(1).toLowerCase() : '';
+          return word ? word[0] + (hasLowerCase ? word.substring(1) : word.substring(1).toLowerCase()) : '';
         } else {
           return capitalize(word.toLowerCase());
         }
diff --git a/tests/case-test.ts b/tests/case-test.ts
index 15c2536cf..1e5a55764 100644
--- a/tests/case-test.ts
+++ b/tests/case-test.ts
@@ -16,6 +16,10 @@ describe('case', () => {
     expect(maybeSnakeToCamel('FOO_BAR', keys)).toEqual('FooBar');
   });
 
+  it('leaves existing mixed cases', () => {
+    expect(maybeSnakeToCamel('clientI_d', keys)).toEqual('clientID');
+  });
+
   it('leaves the first character as it was', () => {
     expect(maybeSnakeToCamel('Foo_Bar', keys)).toEqual('FooBar');
   });