fix: preserve stream-backed file bodies during request interpolation (#7690)

packages/bruno-cli/tests/runner/interpolate-vars.spec.js

@@ -1,6 +1,25 @@
 const { describe, it, expect } = require('@jest/globals');
 const interpolateVars = require('../../src/runner/interpolate-vars');
 
+describe('interpolate-vars: interpolateVars', () => {
+  it('keeps stream-backed JSON request bodies intact', () => {
+    const streamPayload = {
+      pipe: jest.fn(),
+      path: '/tmp/allocations.json'
+    };
+    const request = {
+      method: 'POST',
+      mode: 'file',
+      url: 'http://api.example/upload',
+      headers: { 'content-type': 'application/json' },
+      data: streamPayload
+    };
+
+    const result = interpolateVars(request, { shouldNotApply: 'value' }, null, null);
+    expect(result.data).toBe(streamPayload);
+   });
+});
+
 describe('interpolate-vars: api key header name sidecar', () => {
   it('interpolates apiKeyHeaderName in lockstep with interpolated header keys', () => {
     const request = {