Closes#1492

Description

Implements Phase 1 and begins Phase 2 of migrating test infrastructure frommigueleliasweb/go-github-mock tostretchr/testify-based HTTP mocking. Consolidates testing dependencies while establishing patterns for incremental migration of remaining test files.

Migration Status: 2 of 16 test files migrated (454 lines), 14 files remaining (~14,210 lines).

Changes

New HTTP Mocking Infrastructure (pkg/github/helper_test.go)

• MockHTTPClientWithHandlers: Route-based HTTP client mocking with GitHub API path patterns

  // Before: go-github-mockmock.NewMockedHTTPClient(mock.WithRequestMatch(mock.GetReposByOwnerByRepo,mockRepo),)// After: testify-based with local constantsMockHTTPClientWithHandlers(map[string]http.HandlerFunc{GetReposByOwnerByRepo:mockResponse(t,http.StatusOK,mockRepo),})

• Path pattern matching: Supports{owner},{repo},{tree} wildcards for flexible endpoint matching
• executeHandler: Eliminates response creation duplication across transport implementations
• Local endpoint pattern constants: Defines GitHub API endpoint patterns as constants inhelper_test.go:
  • GetReposByOwnerByRepo
  • GetReposGitTreesByOwnerByRepoByTree
  • GetReposCodeScanningAlertsByOwnerByRepo
  • GetReposCodeScanningAlertsByOwnerByRepoByAlertNumber

Migrated Test Files

• pkg/github/git_test.go (196 lines) - pilot migration, simplest file
• pkg/github/code_scanning_test.go (258 lines) - demonstrates query parameter validation

Both test files now use locally-defined endpoint pattern constants instead of hardcoded paths for better maintainability and consistency.

Dependencies

• Addedgithub.com/stretchr/objx (required by testify/mock)
• Retainedgo-github-mock until full migration complete (will be removed in future PRs)

Tradeoffs

Partial migration over full replacement: Migrated 2 files to establish infrastructure and patterns rather than all 16 files. Reduces PR scope and risk while enabling future incremental work. Full migration deferred to subsequent PRs as outlined in issue.

HTTP-level mocking over interface-based: Maintains current architectural patterns (HTTP transport mocking) rather than introducing interface wrappers around GitHub client. Interface-based approach would require extensive production code changes; HTTP-level mocking achieves dependency consolidation goals with test-only changes.

Local constants over go-github-mock patterns: Defines endpoint pattern constants locally in this repo rather than reusinggo-github-mock patterns. This enables eventual removal of thego-github-mock dependency while maintaining clean, maintainable test code.

No migration documentation: Migration patterns are documented inline in test files and helper functions rather than in a separate documentation file to keep the PR focused on code changes.

Alternatives

sed/automated migration: Considered batch migration via scripting, but endpoint patterns vary significantly across test files (query params, error scenarios, pagination). Manual migration ensures correctness and provides learning for establishing robust patterns.

Remove go-github-mock immediately: Cannot remove dependency until all test files migrated. Interim state maintains both approaches until migration complete.

Reuse mock.EndpointPattern constants: Initially considered reusing existingmock.EndpointPattern constants fromgo-github-mock, but defining local constants better supports the goal of removing thego-github-mock dependency entirely.

• FixesChore: replace migueleliasweb/go-github-mock with stretchr/testify/mock #1492

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