ChromeOS login supports letting the user connect to a restricted network, such as one that has a captive portal (e.g. a terms of service screen).
Testing on a restricted network can be tricky. The most robust way to test is to actually connect your device to a restricted network, but this can greatly slow iteration time. An alternative is to run chrome locally with--proxy-server and run a proxy HTTP server locally that emulates the restricted network.
go-authproxy is a proxy that implements HTTP basic authentication and supports serving a captive portal.
To require HTTP basic authentication
# terminal A$ go-authproxy-basic-auth user:pass# interrupt (e.g. <c-c>) to shutdown# terminal B$ chrome--proxy-server="127.0.0.1:8080"
To show a captive portal
# terminal A$ go-authproxy-captive-portal# interrupt (e.g. <c-c>) to shutdown# terminal B$ chrome--proxy-server="127.0.0.1:8080"