Add comprehensive unit tests for lib package

[Copilot]

Adds unit tests for the lib package targeting high coverage without third-party test dependencies.

Test Coverage

• 95.5% statement coverage achieved
• Remaining ~4.5% is defensive error handling for edge cases impossible to trigger via public API (e.g., IPSet() failures, addresses neither IPv4 nor IPv6)

Test Files Added

• common_test.go - HTTP functions, WantedListExtended JSON unmarshalling
• config_test.go - Config creator registration, inputConvConfig/outputConvConfig unmarshalling
• container_test.go - Container interface operations (Add, Remove, Lookup, GetEntry)
• entry_test.go - Entry type with all processPrefix input types (net.IP, netip.Addr, netip.Prefix, string, pointers)
• converter_test.go - Input/output converter registration
• instance_test.go - Instance lifecycle, config loading (local/remote), Run execution
• error_test.go - Error constant validation
• lib_test.go - Constants, types, ActionsRegistry

Approach

Uses only stdlib testing and net/http/httptest. Mock converters implement InputConverter/OutputConverter interfaces for testing config and instance behavior.

// Example: testing Entry.processPrefix with various input types
func TestEntry_AddPrefix_NetipPrefix(t *testing.T) {
    e := NewEntry("test")
    prefix := netip.MustParsePrefix("192.168.0.0/16")
    if err := e.AddPrefix(prefix); err != nil {
        t.Fatalf("AddPrefix failed: %v", err)
    }
    if !e.hasIPv4Builder() {
        t.Error("expected IPv4 builder")
    }
}

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• invalid.invalid.invalid
  • Triggering command: /tmp/go-build193353414/b001/lib.test /tmp/go-build193353414/b001/lib.test -test.testlogfile=/tmp/go-build193353414/b001/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true _.a (dns block)
  • Triggering command: /tmp/go-build4083291709/b001/lib.test /tmp/go-build4083291709/b001/lib.test -test.testlogfile=/tmp/go-build4083291709/b001/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true _.a d/v2/chacha8.go x64/pkg/tool/linux_amd64/compile-lang=go1.24 (dns block)
  • Triggering command: /tmp/go-build1510732126/b001/lib.test /tmp/go-build1510732126/b001/lib.test -test.paniconexit0 -test.gocoverdir=/tmp/go-build1510732126/b001/gocoverdir -test.timeout=10m0s -test.coverprofile=/tmp/go-build1510732126/b001/_cover_.out jX_qTew6D (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

Please write comprehensive unit tests for lib package and make sure the coverage rate is 100% if possible. Try not to use third-party Golang dependencies if possible.

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