What happens in tests when the requested port is in use? What's verified?

When a requested port is in use, the tests verify that getPort() falls back to finding an alternative available port. Here's what's tested:

Single unavailable preferred port [test.js:L23-L30]: When port 8282 is already bound by a server, calling getPort({port: 8282}) returns a different port number. The test verifies:

• The returned value is a number
• It's greater than 0
• It is not equal to the desired port (8282)

Multiple unavailable preferred ports [test.js:L81-L97]: When all ports in an array (9990, 9991) are already bound, getPort({port: [9990, 9991]}) returns a random available port. The test verifies:

• The returned value is a number between 0 and 65,536
• It doesn't match the first preferred port (9990)
• It doesn't match the second preferred port (9991)

Partially unavailable array [test.js:L72-L80]: When the first port in an array [9090, 9091] is unavailable but the second isn't, getPort() returns the second port in the array, demonstrating it tries alternatives in order before falling back to a random port.

The key verification pattern: the function doesn't fail or throw an error—it gracefully returns an alternative available port instead.

FOLLOW_UPS:

• How does get-port check if a port is available?
• What's the difference between reserve option and default locking?
• How does the exclude option work in practice?