Empty interfaces' extends statements are ignored

[NexZhu]

Bug description

For example, in the following code Object is an empty interface extending BaseObject, which has an id field.

export interface BaseObject {
  "id": string;
}
export interface Object extends BaseObject {}

Running ts-to-zod fails with:

✖ Validating generated types
 ›   Error: 'objectSchema' is not compatible with 'Object':
 ›   Argument of type '{}' is not assignable to parameter of type 'Object'.
 ›     Property '"id"' is missing in type '{}' but required in type 'Object'.
error Command failed with exit code 2.

And running with --skipValidation generates:

// Generated by ts-to-zod
import { z } from "zod";

export const baseObjectSchema = z.object({
  id: z.string(),
});

export const objectSchema = z.object({});

Expected output:

export const objectSchema = baseObjectSchema;

The problematic code is in generateZodSchema.ts, schemaExtensionClauses is handled only when properties.length > 0:

Versions

• Typescript: v4.8.4

[NexZhu]

With #109 applied, there are still some issues with validation.

Input:

export namespace std {
  export interface BaseObject {
    "id": string;
  }
  export interface $Object extends BaseObject {}
}

export interface Base extends std.$Object {
  "createdAt": Date;
}

The output is actually correct with --skipValidation:

// Generated by ts-to-zod
import { z } from 'zod'

export const stdBaseObjectSchema = z.object({
  id: z.string(),
})

export const stdObjectSchema = stdBaseObjectSchema.extend({})

export const baseSchema = stdObjectSchema.extend({
  createdAt: z.date(),
})

But ts-to-zod gave me a validation error:

✖ Validating generated types
 ›   Error: 'Base' is not compatible with 'baseSchema':
 ›   Argument of type 'Base' is not assignable to parameter of type '{ id: string; createdAt: Date; }'.
 ›     Property '"id"' is missing in type 'Base' but required in type '{ id: string; createdAt: Date; }'.