fix: unit test for proxy pagination handling

[barabo]

There were a few issues with the pagination unit test for the proxy.

• it started with a relative URL and then used a full url to follow the 'next' link...
• but the test environment was not using the same hostname & port as what was in the 'next' link...
• so the test was silently throwing away a 'connection refused error' and passing anyway.
• the second half of the test incorrectly referenced the first 'res' result when it seemed to intend to reference the second 'res2' (which was unreferenced)
• after running npm test - the mocha test framework process hung because the second get call failed (I believe, but still not 100% sure why). Running the tests with the npm test -- --exit flag was a workaround, but felt wrong.

After applying these changes npm test works without having to use the --exit flag, and the intended coverage is working again.

[jmandel]

There's a subtle underlying issue where mocha starts the server with a random ephemeral port, but the server believes/expects its port to be whatever's defined in config -- so during tests, searches return invalid Bundle.link.url values.

microsoft-healthcare-madison@965cbfe#diff-f1c404872f48ce2b9a4a9e18262e68a64bb43cbc934a8a4d891d098a1b3a3b62 may be
a better way to approach this, by starting the server in mocha hooks explicitly, ensuring that the actual port matches the configured port.

[vlad-ignatov]

There are multiple issues here, but mostly:

1. The res/res2 mismatch
2. The random port problem

Your solution looks definitely cleaner, but also a little harder to read. I think I've fixed these in 92fec07. Please give it a try and feel free to reapply your changes on top of that if needed.