fix: apply undefined-filter to assign

src/main/ts/util.ts

@@ -26,7 +26,8 @@ export const isStringLiteral = (pieces: any) => pieces?.every?.((p: any) => type
 
 export const assign = <T, E>(target: T, ...extras: E[]): T =>
   Object.defineProperties(target, extras.reduce<Record<string, any>>((m: any, extra) =>
-    ({...m, ...Object.getOwnPropertyDescriptors(extra)}), {}))
+    ({...m, ...Object.fromEntries(Object.entries(Object.getOwnPropertyDescriptors(extra))
+        .filter(([,v]) => !Object.hasOwn(v, 'value') || v.value !== undefined))}), {}))
 
 export const quote = (arg: string) => {
   if (/^[\w./:=@-]+$/i.test(arg) || arg === '') {

src/scripts/test.mjs

@@ -2,7 +2,9 @@
 
 import glob from 'fast-glob'
 import { pathToFileURL } from 'node:url'
+import process from 'node:process'
 
-const suites = await glob('src/test/**/*.test.{ts,cjs,mjs}', {cwd: process.cwd(), absolute: true, onlyFiles: true})
+const focused = process.argv.slice(2)
+const suites = focused.length ? focused : await glob('src/test/**/*.test.{ts,cjs,mjs}', {cwd: process.cwd(), absolute: true, onlyFiles: true})
 
 await Promise.all(suites.map(suite => import(pathToFileURL(suite))))

src/test/ts/util.test.ts

@@ -0,0 +1,10 @@
+import * as assert from 'node:assert'
+import { describe, it } from 'node:test'
+import { assign } from '../../main/ts/util.js'
+
+describe('util', () => {
+  it('assign()', () => {
+    assert.deepEqual(assign({a: 1}, {b: 2}), {a: 1, b: 2})
+    assert.deepEqual(assign({a: 1}, {a: undefined}), {a: 1})
+  })
+})