@redocly/openapi-core/src/rules/common/required-string-property-missing-min-length.ts

See https://github.com/Redocly/redocly-cli

import { UserContext } from '../../walk';
import { Oas3Schema, Oas3_1Schema } from '../../typings/openapi';
import { Oas2Schema } from 'core/src/typings/swagger';
import { Oas3Rule } from 'core/src/visitors';

export const RequiredStringPropertyMissingMinLength: Oas3Rule = () => {
  let skipSchemaProperties: boolean;
  let requiredPropertiesSet: Set<string>;

  return {
    Schema: {
      enter(schema: Oas3Schema | Oas3_1Schema | Oas2Schema) {
        if (!schema?.required) {
          skipSchemaProperties = true;
          return;
        }
        requiredPropertiesSet = new Set(schema.required);
        skipSchemaProperties = false;
      },

      SchemaProperties: {
        skip() {
          return skipSchemaProperties;
        },

        Schema: {
          enter(
            schema: Oas3Schema | Oas3_1Schema | Oas2Schema,
            { key, location, report }: UserContext
          ) {
            if (requiredPropertiesSet.has(key as string) && schema.type === 'string') {
              if (!schema?.minLength) {
                report({
                  message: 'Property minLength is required.',
                  location: location.key(),
                });
              }
            }
          },
        },
      },
    },
  };
};