fix: key ending in number

RossWilliams · RossWilliams · commit f9e828fed3ec · 2024-01-15T10:47:41.000Z
resolves #64
diff --git a/src/caseConvert.ts b/src/caseConvert.ts
@@ -192,7 +192,12 @@ export type ToSnake<S extends string | number | symbol> = S extends string
         ? Caps extends CapitalChars
           ? Head extends Lowercase<Head> /* 'abcD' */
             ? Caps extends Numbers
-              ? never /* stop union type forming */
+              ? // Head exists and is lowercase, tail does not, Caps is a number, we may be in a sub-select
+                // if head ends with number, don't split head an Caps, keep contiguous numbers together
+                Head extends `${string}${Numbers}`
+                ? never
+                : // head does not end in number, safe to split. 'abc2' -> 'abc_2'
+                  `${ToSnake<Head>}_${Caps}`
               : `${ToSnake<Head>}_${ToSnake<Caps>}` /* 'abcD' 'abc25' */
             : never /* stop union type forming */
           : never
diff --git a/test/caseConvert.bugs.test.ts b/test/caseConvert.bugs.test.ts
@@ -141,6 +141,15 @@ describe('bug fixes', () => {
     console.log(convertedSnakeObj.array);
     expect(convertedSnakeObj.array[0] instanceof Date).toBeTruthy();
   });
+
+  it('#64 - camel to snake missing property name ending in a number', () => {
+    const camelObject = {
+      aaaBbb1: 'a',
+    };
+    const snakeObject = objectToSnake(camelObject);
+    expect(snakeObject.aaa_bbb_1).toEqual('a');
+    expect(Object.keys(snakeObject)).toHaveLength(1);
+  });
 });
 
 // Bug #50
diff --git a/test/caseConvert.test.ts b/test/caseConvert.test.ts
@@ -313,6 +313,8 @@ type T23 = ToSnake<'abc25A50'>;
 const _s23: AssertEqual<T23, 'abc_25_a50'> = true;
 type T25 = ToSnake<'a'>;
 const _s25: AssertEqual<T25, 'a'> = true;
+type T36 = ToSnake<'abc1'>;
+const _s36: AssertEqual<T36, 'abc_1'> = true;
 
 interface I24 {
   optionalObject?: {
