diff --git a/package.json b/package.json
index c7b8506..cdeea62 100644
--- a/package.json
+++ b/package.json
@@ -80,7 +80,7 @@
   "scripts": {
     "build": "rimraf \"lib/**/*.d.ts\" \"test/**/*.d.ts\" \"*.d.ts\" && tsc && type-coverage",
     "format": "remark . -qfo --ignore-pattern test/ && prettier . -w --loglevel warn && xo --fix",
-    "test-api": "node --conditions development test/index.js",
+    "test-api": "tape test/index.js test/other-branches.js",
     "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov npm run test-api",
     "test": "npm run build && npm run format && npm run test-coverage"
   },
diff --git a/test/fixtures/other-branches.md b/test/fixtures/other-branches.md
deleted file mode 100644
index 2f7432c..0000000
--- a/test/fixtures/other-branches.md
+++ /dev/null
@@ -1,8 +0,0 @@
-# Links to other branches
-
-- [Same branch, working link](https://github.com/wooorm/test/blob/main/examples/github.md#hello): Nothing to report.
-- [Other branch, working link](https://github.com/wooorm/test/blob/foo-bar/examples/github.md#hello): Nothing to ignore.
-- [Same branch, no such heading](https://github.com/wooorm/test/blob/main/examples/github.md#world): Should be reported.
-- [Other branch, no such heading](https://github.com/wooorm/test/blob/foo-bar/examples/github.md#world): Should be ignored.
-- [Same branch, no such file](https://github.com/wooorm/test/blob/main/examples/world.md#hello): Should be reported.
-- [Other branch, no such file](https://github.com/wooorm/test/blob/foo-bar/examples/world.md#hello): Should be ignored.
diff --git a/test/index.js b/test/index.js
index 458a84a..ad0655f 100644
--- a/test/index.js
+++ b/test/index.js
@@ -1006,31 +1006,3 @@ test('remark-validate-links', async (t) => {
 
   t.end()
 })
-
-test('links to other branches', async (t) => {
-  const {stderr} = await exec(
-    [
-      bin,
-      '--no-config',
-      '--no-ignore',
-      '--use',
-      '"../../index.js=repository:\\"wooorm/test#main\\""',
-      '--use',
-      '../sort.js',
-      'other-branches.md'
-    ].join(' ')
-  )
-  t.deepEqual(
-    strip(stderr),
-    [
-      'other-branches.md',
-      '  5:3-5:100  warning  Link to unknown heading in `examples/github.md`: `world`  missing-heading-in-file  remark-validate-links',
-      '   7:3-7:96  warning  Link to unknown file: `examples/world.md`                 missing-file             remark-validate-links',
-      '   7:3-7:96  warning  Link to unknown heading in `examples/world.md`: `hello`   missing-heading-in-file  remark-validate-links',
-      '',
-      '⚠ 3 warnings',
-      ''
-    ].join('\n'),
-    'should ignore links to other branches'
-  )
-})
diff --git a/test/other-branches.js b/test/other-branches.js
new file mode 100644
index 0000000..f173d43
--- /dev/null
+++ b/test/other-branches.js
@@ -0,0 +1,93 @@
+import {remark} from 'remark'
+import test from 'tape'
+import {engine as engineCb} from 'unified-engine'
+import {promisify} from 'node:util'
+import {VFile} from 'vfile'
+import remarkValidateLinks from '../index.js'
+
+const engine = promisify(engineCb)
+
+// Should ignore links to other branches.
+const options = {repository: 'https://github.com/wooorm/test.git#main'}
+
+test('same branch, working link', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/main/examples/github.md#hello)'
+    ),
+    [],
+    'nothing to report'
+  )
+})
+
+test('other branch, working link', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/foo-bar/examples/github.md#hello)'
+    ),
+    [],
+    'nothing to ignore'
+  )
+})
+
+test('same branch, no such heading', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/main/examples/github.md#world)'
+    ),
+    [
+      'input.md:1:1-1:70: Link to unknown heading in `examples/github.md`: `world`'
+    ],
+    'should be reported'
+  )
+})
+
+test('other branch, no such heading', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/foo-bar/examples/github.md#world)'
+    ),
+    [],
+    'should be ignored'
+  )
+})
+
+test('same branch, no such file', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/main/examples/world.md#hello)'
+    ),
+    [
+      'input.md:1:1-1:69: Link to unknown file: `examples/world.md`',
+      'input.md:1:1-1:69: Link to unknown heading in `examples/world.md`: `hello`'
+    ],
+    'should be reported'
+  )
+})
+
+test('other branch, no such file', async (t) => {
+  t.deepEqual(
+    await process(
+      '[](https://github.com/wooorm/test/blob/foo-bar/examples/world.md#hello)'
+    ),
+    [],
+    'should be ignored'
+  )
+})
+
+/**
+ * Run the plugin on a markdown test case and return a list of stringified messages.
+ * unified-engine is needed to cross-reference links between files, by creating a FileSet.
+ *
+ * @param {string} value
+ */
+async function process(value) {
+  const file = new VFile({value, path: 'input.md'})
+  await engine({
+    processor: remark,
+    files: [file],
+    plugins: [[remarkValidateLinks, options]],
+    silent: true
+  })
+  return file.messages.map((message) => String(message))
+}