[test-improver] Improve tests for urlutil package

[github-actions]

File Analyzed

• Test File: internal/urlutil/domains_test.go (new file)
• Package: internal/urlutil
• Implementation: internal/urlutil/domains.go (101 lines)

Improvements Made

1. Increased Coverage

• ✅ Created domains_test.go from scratch — the package had zero test coverage
• Previous Coverage: 0%
• New Coverage: 97.8%
• Improvement: +97.8%

2. Comprehensive Test Cases (50 total)

TestExtractURLDomains — 30 subtests covering:

• Empty/no-URL strings → nil
• HTTP and HTTPS schemes
• Case-insensitive scheme matching (HTTPS://, Https://)
• Hostname lowercasing (EXAMPLE.COM → example.com)
• URL components: path, query string, fragment, port, userinfo, IPv4
• All trailing punctuation characters stripped: , . ; : ! ) ] } "
• Deduplication of identical hostnames across multiple URLs
• Sorted output for multiple distinct domains
• URL embedded in Markdown and HTML markup
• Subdomains preserved as distinct entries
• Error paths: invalid percent-encoding (%GG, %ZZ) triggers url.Parse error → URL skipped
• Empty hostname path: (user/redacted)@ (userinfo with no host) → nil

TestExtractURLDomainsFromValue — 20 subtests covering:

• All four collectURLDomains type branches: string, map[string]any, []any, []map[string]any
• Unmatched types (int, bool, nil) are ignored
• Nested map[string]any inside map[string]any
• []any containing nested maps
• Cross-value deduplication and sorted output
• Empty slices and maps with non-URL values → nil

3. Idiomatic Testing Patterns

• ✅ Table-driven tests with t.Parallel() at both parent and subtest level
• ✅ Uses testify/assert throughout — consistent with codebase conventions
• ✅ Descriptive subtest names that document each tested behavior

Test Execution

All 50 tests pass:

ok  github.com/github/gh-aw-mcpg/internal/urlutil  0.006s  coverage: 97.8% of statements
ExtractURLDomainsFromValue  100.0%
collectURLDomains           100.0%
ExtractURLDomains            96.0%
total:                       97.8%

Why This File?

internal/urlutil/domains.go was the only package in the internal/ tree with 0% test coverage — no test file existed at all. The package provides URL domain extraction used across the codebase, making thorough testing especially valuable. The functions have clear, verifiable behavior across a range of input types and edge cases.

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[Copilot]

Pull request overview

Adds initial unit test coverage for the internal/urlutil domain-extraction helpers, which parse strings / nested values and return sorted, deduplicated hostname lists.

Changes:

• Introduces a new domains_test.go with table-driven tests for ExtractURLDomains.
• Adds coverage for ExtractURLDomainsFromValue across supported input shapes (string, map[string]any, []any, []map[string]any), including recursion + deduplication.

Show a summary per file

File	Description
internal/urlutil/domains_test.go	New test suite covering URL domain extraction and recursive value-walking behavior.

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• Files reviewed: 1/1 changed files
• Comments generated: 2