fix: camelCase assertion for single letter (#1735)

.changeset/fresh-cheetahs-love.md

@@ -0,0 +1,6 @@
+---
+"@redocly/openapi-core": patch
+"@redocly/cli": patch
+---
+
+Fixed `camelCase` assertion for single-letter values.

packages/core/src/rules/common/assertions/__tests__/asserts.test.ts

@@ -317,6 +317,14 @@ describe('oas3 assertions', () => {
         expect(asserts.casing(['testExample', 'fooBar'], 'camelCase', assertionProperties)).toEqual(
           []
         );
+        expect(asserts.casing(['f'], 'camelCase', assertionProperties)).toEqual([]);
+        expect(asserts.casing(['Q'], 'camelCase', assertionProperties)).toEqual([
+          {
+            message: '"Q" should use camelCase',
+            location: baseLocation.child('Q').key(),
+          },
+        ]);
+        expect(asserts.casing(['fQ'], 'camelCase', assertionProperties)).toEqual([]);
         expect(asserts.casing(['testExample', 'FooBar'], 'camelCase', assertionProperties)).toEqual(
           [
             {

packages/core/src/rules/common/assertions/asserts.ts

@@ -243,7 +243,7 @@ export const asserts: Asserts = {
     if (typeof value === 'undefined' || isPlainObject(value)) return []; // property doesn't exist or is an object, no need to lint it with this assert
     const values = Array.isArray(value) ? value : [value];
     const casingRegexes: Record<string, RegExp> = {
-      camelCase: /^[a-z][a-zA-Z0-9]+$/g,
+      camelCase: /^[a-z][a-zA-Z0-9]*$/g,
       'kebab-case': /^([a-z][a-z0-9]*)(-[a-z0-9]+)*$/g,
       snake_case: /^([a-z][a-z0-9]*)(_[a-z0-9]+)*$/g,
       PascalCase: /^[A-Z][a-zA-Z0-9]+$/g,