[test] Add tests for config.normalizeAgentID, effectiveAgentID, and validateToolResponseFilters

[github-actions]

Test Coverage Improvement

Brings three under-tested internal/config functions to 100% coverage.

Functions Analyzed

Function	Package	Previous Coverage	New Coverage
GatewayConfig.normalizeAgentID	internal/config	80.0%	100%
GatewayConfig.effectiveAgentID	internal/config	85.7%	100%
validateToolResponseFilters	internal/config	86.7%	100%

Why These Functions?

All three had the highest complexity-to-coverage gap in the internal/config package — each had concrete uncovered branches containing non-trivial logic:

• normalizeAgentID: The conflict-detection branch (both gateway.agent_id and gateway.api_key set to different values) and the nil-receiver guard were both uncovered.
• effectiveAgentID: The nil-receiver guard was uncovered.
• validateToolResponseFilters: Both the gojq.WithEnvironLoader closure body and the gojq.Compile error path were uncovered.

Tests Added

internal/config/config_core_agent_id_coverage_test.go (new file)

• ✅ TestEffectiveAgentID — 6 table-driven sub-cases:

  • nil receiver (returns "")
  • explicit field set
  • non-explicit AgentID non-empty
  • APIKey fallback (AgentID empty)
  • zero value (both empty)
  • prefer AgentID over APIKey when non-explicit

• ✅ TestNormalizeAgentID — 6 table-driven sub-cases:

  • nil receiver no-op
  • only api_key set (legacy deprecation path)
  • both set to the same value (no conflict)
  • both set to different values (conflict warning path — the key uncovered branch)
  • only agent_id set (explicit path)
  • neither set (zero-value no-op)

• ✅ 5 LoadFromFile integration tests exercising all four TOML field combinations, including the agent_id/api_key conflict path end-to-end.

internal/config/validate_helpers_coverage_test.go (modified)

• ✅ $ENV.SOME_VARIABLE filter — forces gojq to invoke the WithEnvironLoader closure during compilation, covering the env-loader branch.
• ✅ $undefinedVar | .field filter — parses OK but fails at gojq.Compile with "variable not defined", covering the compile-error return path.

Coverage Report

Before:
  GatewayConfig.normalizeAgentID       80.0%
  GatewayConfig.effectiveAgentID       85.7%
  validateToolResponseFilters          86.7%
  internal/config total                97.3%

After:
  GatewayConfig.normalizeAgentID      100.0%
  GatewayConfig.effectiveAgentID      100.0%
  validateToolResponseFilters         100.0%
  internal/config total                97.6%
  all testable packages total          98.4%

Test Execution

All tests pass (run with -tags "tty_stub testify_yaml_fail" to avoid unavailable module dependencies in the CI sandbox):

ok  	github.com/github/gh-aw-mcpg/internal/config	(all tests pass)

gofmt and go vet clean on all changed files.

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Generated by Test Coverage Improver
Next run will target the next most complex under-tested function

Warning

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• go.yaml.in
• golang.org
• google.golang.org
• gopkg.in
• proxy.golang.org

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network:
  allowed:
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    - "go.yaml.in"
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    - "proxy.golang.org"

See Network Configuration for more information.

Generated by Test Coverage Improver · 2.8K AIC · ⊞ 28.7K · ◷

[Copilot]

Pull request overview

This PR improves test coverage in internal/config by adding targeted unit/integration tests for gateway agent ID normalization/resolution and for jq tool-response-filter validation edge cases (including gojq compile-time branches).

Changes:

• Added a new test file covering GatewayConfig.effectiveAgentID, GatewayConfig.normalizeAgentID, and several LoadFromFile agent_id/api_key combinations.
• Extended validateToolResponseFilters direct-call tests to exercise the gojq environ-loader option path and the gojq compile-error (non-parse) path.

Show a summary per file

File	Description
internal/config/validate_helpers_coverage_test.go	Adds two direct-call cases to cover gojq env-loader invocation and gojq compile-error handling in tool_response_filters validation.
internal/config/config_core_agent_id_coverage_test.go	New tests for agent ID precedence/normalization and TOML LoadFromFile integration coverage for agent_id/api_key combinations.

Copilot's findings

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• Files reviewed: 2/2 changed files
• Comments generated: 3