refactor: generate zero-column test data on-demand instead of checking in binary

Remove test/data/zero_column_batch.arrow and generate IPC buffer
in the test using the JS writer, per review feedback.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: rustyconover

test/data/zero_column_batch.arrow

@@ -16,8 +16,6 @@
 // under the License.
 
 import '../../../jest-extensions.js';
-import { readFileSync } from 'node:fs';
-import path from 'node:path';
 import {
     makeData,
     RecordBatch,
@@ -27,14 +25,28 @@ import {
     tableFromIPC,
 } from 'apache-arrow';
 
-const testDataDir = path.resolve(process.cwd(), 'test/data');
+/** Helper to create a zero-column IPC stream buffer with the given number of rows. */
+function createZeroColumnIPCBuffer(numRows: number): Uint8Array {
+    const schema = new Schema([]);
+    const data = makeData({
+        type: new Struct([]),
+        length: numRows,
+        nullCount: 0,
+        children: [],
+    });
+    const batch = new RecordBatch(schema, data);
+    const writer = new RecordBatchStreamWriter();
+    writer.write(batch);
+    writer.finish();
+    return writer.toUint8Array(true);
+}
 
 describe('Zero-column RecordBatch numRows preservation', () => {
 
-    describe('PyArrow interop', () => {
+    describe('IPC round-trip', () => {
 
-        test('should read PyArrow zero-column stream and preserve numRows', () => {
-            const buffer = readFileSync(path.resolve(testDataDir, 'zero_column_batch.arrow'));
+        test('should read zero-column stream and preserve numRows', () => {
+            const buffer = createZeroColumnIPCBuffer(100);
             const table = tableFromIPC(buffer);
 
             expect(table.numRows).toBe(100);
@@ -44,33 +56,6 @@ describe('Zero-column RecordBatch numRows preservation', () => {
         });
     });
 
-    describe('JS round-trip', () => {
-
-        test('zero-column batch should round-trip through IPC stream writer', () => {
-            const schema = new Schema([]);
-            const data = makeData({
-                type: new Struct([]),
-                length: 100,
-                nullCount: 0,
-                children: [],
-            });
-            const batch = new RecordBatch(schema, data);
-            expect(batch.numRows).toBe(100);
-            expect(batch.numCols).toBe(0);
-
-            const writer = new RecordBatchStreamWriter();
-            writer.write(batch);
-            writer.finish();
-            const buffer = writer.toUint8Array(true);
-
-            const table = tableFromIPC(buffer);
-            expect(table.numRows).toBe(100);
-            expect(table.numCols).toBe(0);
-            expect(table.batches).toHaveLength(1);
-            expect(table.batches[0].numRows).toBe(100);
-        });
-    });
-
     describe('Direct constructor', () => {
 
         test('RecordBatch constructor preserves length for zero-column data', () => {