jstests/query_golden/unwind.js is a golden test, that is, a test that produces some output which is then compared to the expected output that is stored in jstests/query_golden/expected_output directory.

Going forward, we would like all golden tests to produce output in markdown format, so that large outputs can be rendered and viewed in a more eye-friendly way.

To run the test:
```
buildscripts/resmoke.py run --suite query_golden_classic jstests/query_golden/unwind.js
```

You can see some of the tests that are named "*_md.js" to get an idea. The golden test framework is documented at https://github.com/10gen/mongo/blob/master/docs/golden_data_test_framework.md?plain=1