refactor: remove duplicated code patterns in resolver and cmd packages

[Copilot]

Identified and eliminated ~30 lines of duplicated code across resolver String() implementations and API client initialization.

Changes

Resolver String() Methods

• Extracted common upstream formatting logic into formatUpstreamResolvers() helper in resolver/resolver.go
• Refactored StrictResolver and ParallelBestResolver to use shared implementation

Before:

func (r *StrictResolver) String() string {
    resolvers := *r.resolvers.Load()
    upstreams := make([]string, len(resolvers))
    for i, s := range resolvers {
        upstreams[i] = s.resolver.String()
    }
    return fmt.Sprintf("%s upstreams '%s (%s)'", strictResolverType, r.cfg.Name, strings.Join(upstreams, ","))
}

After:

func (r *StrictResolver) String() string {
    return formatUpstreamResolvers(strictResolverType, r.cfg.Name, *r.resolvers.Load())
}

API Client Creation

• Added newAPIClient() helper in cmd/root.go for consistent client initialization and error handling
• Updated 6 command functions across blocking.go, cache.go, lists.go, and query.go

Before:

client, err := api.NewClientWithResponses(apiURL())
if err != nil {
    return fmt.Errorf("can't create client: %w", err)
}

After:

client, err := newAPIClient()
if err != nil {
    return err
}

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:

• 127.0.0.2
  • Triggering command: /home/REDACTED/work/blocky/blocky/resolver/resolver.test --test.timeout=0 --ginkgo.seed=1763102286 --ginkgo.timeout=59m43.553297085s --ginkgo.grace-period=30s --ginkgo.label-filter=!e2e --ginkgo.parallel.process=1 --ginkgo.parallel.total=1 --ginkgo.succinct --test.coverprofile=/home/REDACTED/work/blocky/blocky/resolver/coverage.txt (packet block)
  • Triggering command: /home/REDACTED/work/blocky/blocky/resolver/resolver.test --test.timeout=0 --ginkgo.seed=1763102854 --ginkgo.timeout=59m45.066627341s --ginkgo.grace-period=30s --ginkgo.label-filter=!e2e --ginkgo.parallel.process=1 --ginkgo.parallel.total=1 --ginkgo.succinct --test.coverprofile=/home/REDACTED/work/blocky/blocky/resolver/coverage.txt (packet block)
• example.com
  • Triggering command: /home/REDACTED/work/blocky/blocky/cmd/cmd.test --test.timeout=0 --ginkgo.seed=1763102286 --ginkgo.timeout=59m49.735667649s --ginkgo.grace-period=30s --ginkgo.label-filter=!e2e --ginkgo.parallel.process=1 --ginkgo.parallel.total=1 --ginkgo.succinct --test.coverprofile=/home/REDACTED/work/blocky/blocky/cmd/coverage.txt (dns block)
  • Triggering command: /home/REDACTED/work/blocky/blocky/server/server.test --test.timeout=0 --ginkgo.seed=1763102286 --ginkgo.timeout=59m31.762891604s --ginkgo.grace-period=30s --ginkgo.label-filter=!e2e --ginkgo.parallel.process=1 --ginkgo.parallel.total=1 --ginkgo.succinct --test.coverprofile=/home/REDACTED/work/blocky/blocky/server/coverage.txt (dns block)
  • Triggering command: /home/REDACTED/work/blocky/blocky/cmd/cmd.test --test.timeout=0 --ginkgo.seed=1763102854 --ginkgo.timeout=59m51.268400917s --ginkgo.grace-period=30s --ginkgo.label-filter=!e2e --ginkgo.parallel.process=1 --ginkgo.parallel.total=1 --ginkgo.succinct --test.coverprofile=/home/REDACTED/work/blocky/blocky/cmd/coverage.txt (dns block)
• xyz.example.com
  • Triggering command: /home/REDACTED/work/blocky/blocky/lists/lists.test --test.timeout=0 --ginkgo.seed=1763102286 --ginkgo.timeout=59m47.410342067s --ginkgo.grace-period=30s --ginkgo.label-filter=!e2e --ginkgo.parallel.process=1 --ginkgo.parallel.total=1 --ginkgo.succinct --test.coverprofile=/home/REDACTED/work/blocky/blocky/lists/coverage.txt (dns block)
  • Triggering command: /home/REDACTED/work/blocky/blocky/lists/lists.test --test.timeout=0 --ginkgo.seed=1763102854 --ginkgo.timeout=59m48.940083249s --ginkgo.grace-period=30s --ginkgo.label-filter=!e2e --ginkgo.parallel.process=1 --ginkgo.parallel.total=1 --ginkgo.succinct --test.coverprofile=/home/REDACTED/work/blocky/blocky/lists/coverage.txt (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

Find and refactor duplicated code

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.80%. Comparing base (5657ce8) to head (15e6367).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/blocking.go	50.00%	3 Missing ⚠️
cmd/root.go	60.00%	1 Missing and 1 partial ⚠️
cmd/cache.go	50.00%	1 Missing ⚠️
cmd/lists.go	50.00%	1 Missing ⚠️
cmd/query.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1932      +/-   ##
==========================================
- Coverage   91.83%   91.80%   -0.03%     
==========================================
  Files          90       90              
  Lines        6257     6259       +2     
==========================================
  Hits         5746     5746              
- Misses        381      382       +1     
- Partials      130      131       +1     

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