diff --git a/src/toJson.js b/src/toJson.js
index 2aae9c5..bf81685 100644
--- a/src/toJson.js
+++ b/src/toJson.js
@@ -7,18 +7,16 @@
  * @returns {unknown} converted object
  */
 export function toJson(obj) {
-  if (typeof obj === 'bigint') {
-    return Number(obj)
-  } else if (Array.isArray(obj)) {
-    return obj.map(toJson)
-  } else if (obj instanceof Object) {
+  if (obj === undefined) return null
+  if (typeof obj === 'bigint') return Number(obj)
+  if (Array.isArray(obj)) return obj.map(toJson)
+  if (obj instanceof Object) {
     /** @type {Record<string, unknown>} */
     const newObj = {}
     for (const key of Object.keys(obj)) {
       newObj[key] = toJson(obj[key])
     }
     return newObj
-  } else {
-    return obj
   }
+  return obj
 }
diff --git a/test/files/addrtype-missing-value.json b/test/files/addrtype-missing-value.json
new file mode 100644
index 0000000..f7a432c
--- /dev/null
+++ b/test/files/addrtype-missing-value.json
@@ -0,0 +1,12 @@
+[
+  [ "Block" ],
+  [ "Intersection" ],
+  [ "Block" ],
+  [ "Block" ],
+  [ null ],
+  [ "Block" ],
+  [ "Intersection" ],
+  [ "Block" ],
+  [ "Block" ],
+  [ "Intersection" ]
+]
diff --git a/test/files/rowgroups.json b/test/files/rowgroups.json
new file mode 100644
index 0000000..9d5553b
--- /dev/null
+++ b/test/files/rowgroups.json
@@ -0,0 +1,17 @@
+[
+  [ 1 ],
+  [ 2 ],
+  [ 3 ],
+  [ 4 ],
+  [ 5 ],
+  [ 6 ],
+  [ 7 ],
+  [ 8 ],
+  [ 9 ],
+  [ 10 ],
+  [ 11 ],
+  [ 12 ],
+  [ 13 ],
+  [ 14 ],
+  [ 15 ]
+]
diff --git a/test/read.test.js b/test/read.test.js
index 9159b9d..6166f29 100644
--- a/test/read.test.js
+++ b/test/read.test.js
@@ -1,58 +1,23 @@
+import fs from 'fs'
 import { describe, expect, it } from 'vitest'
 import { parquetRead } from '../src/hyparquet.js'
 import { toJson } from '../src/toJson.js'
-import { fileToAsyncBuffer } from './helpers.js'
+import { fileToAsyncBuffer, fileToJson } from './helpers.js'
 
 describe('parquetMetadataAsync', () => {
-  it('should parse data from addrtype-missing-value.parquet', async () => {
-    const asyncBuffer = fileToAsyncBuffer('test/files/addrtype-missing-value.parquet')
-    await parquetRead({
-      file: asyncBuffer,
-      onComplete: (rows) => {
-        expect(rows).toEqual(addrtypeData)
-      },
-    })
-  })
-
-  it('should parse data from rowgroups.parquet', async () => {
-    const asyncBuffer = fileToAsyncBuffer('test/files/rowgroups.parquet')
-    await parquetRead({
-      file: asyncBuffer,
-      onComplete: (rows) => {
-        expect(toJson(rows)).toEqual(rowgroupsData)
-      },
-    })
+  it('should parse metadata from all test files', async () => {
+    const files = fs.readdirSync('test/files')
+    for (const file of files) {
+      if (!file.endsWith('.parquet')) continue
+      const asyncBuffer = fileToAsyncBuffer(`test/files/${file}`)
+      await parquetRead({
+        file: asyncBuffer,
+        onComplete: (rows) => {
+          const base = file.replace('.parquet', '')
+          const expected = fileToJson(`test/files/${base}.json`)
+          expect(toJson(rows)).toEqual(expected)
+        },
+      })
+    }
   })
 })
-
-// Parquet v1 from DuckDB
-const addrtypeData = [
-  ['Block'],
-  ['Intersection'],
-  ['Block'],
-  ['Block'],
-  [undefined],
-  ['Block'],
-  ['Intersection'],
-  ['Block'],
-  ['Block'],
-  ['Intersection'],
-]
-
-const rowgroupsData = [
-  [1],
-  [2],
-  [3],
-  [4],
-  [5],
-  [6],
-  [7],
-  [8],
-  [9],
-  [10],
-  [11],
-  [12],
-  [13],
-  [14],
-  [15],
-]