[test-improver] Improve tests for validateSingleAgentPolicy error paths

[github-actions]

Summary

Improved internal/config/agent_policy_test.go by adding coverage for previously-untested error branches in validateSingleAgentPolicy (internal/config/agent_policy.go).

File analyzed

internal/config/agent_policy_test.go (tests internal/config/agent_policy.go)

Improvements made

Added two new test functions:

• TestValidateSingleAgentPolicy_ErrorPaths — table-driven test covering:
  • empty server entry (Servers: []string{""})
  • unknown server reference
  • duplicate server entry
  • tools map referencing a server not in the policy's Servers list
  • empty tool entry
  • duplicate tool entry
  • invalid AllowOnly sub-policy (propagated validation error)
• TestValidateSingleAgentPolicy_ValidPolicySucceeds — a happy-path sanity check that a fully valid policy returns no error.

All new tests use testify (require.Error/assert.ErrorContains/assert.NotContains/assert.NoError), consistent with the existing file's conventions, and assert that the raw agent ID is never leaked into error messages (matching the existing whitespace test's behavior).

Coverage before/after

• validateSingleAgentPolicy: 87.5% → 100%
• internal/config package total: 96.9% → 97.1%

Test output

go test -run "TestValidateSingleAgentPolicy" -v ./internal/config/
--- PASS: TestValidateSingleAgentPolicy_RejectsSurroundingWhitespace (0.00s)
--- PASS: TestValidateSingleAgentPolicy_ErrorPaths (0.00s)
--- PASS: TestValidateSingleAgentPolicy_ValidPolicySucceeds (0.00s)
PASS
ok  	github.com/github/gh-aw-mcpg/internal/config	0.008s

Also verified:

• go test -count=3 ./internal/config/... — all pass (stability check)
• go vet ./internal/config/ — clean
• gofmt -l internal/config/agent_policy_test.go — no output (already formatted)

No existing tests were modified or removed; all changes are additive.

Generated by Test Improver · copilot · auto · 133.9 AIC · ⊞ 8.6K · ◷

[Copilot]

🟢 Approval recommended

The additive tests accurately cover the intended validation branches and follow existing conventions.

Pull request overview

Adds targeted coverage for validateSingleAgentPolicy validation paths.

Changes:

• Adds table-driven error-path tests.
• Verifies agent IDs remain redacted.
• Adds a valid-policy sanity test.

File summaries

File	Description
internal/config/agent_policy_test.go	Expands policy validation coverage.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Balanced

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[github-actions]

🔒 mcpg Read-Only Stress — gVisor

Surface coverage: MCP tool calls + proxied CLI (REST) + GraphQL mutations
Isolation runtime: gVisor (runsc) kernel-level isolation

Part	Surface	Op	Result	Expected	Status
A	MCP	reads (list_issues/list_prs/get_file/list_commits)	data returned	ALLOWED	✅
B	MCP	writes (reaction/star/issue/comment/branch/file/PR)	tool not found	BLOCKED	⚠️
C	CLI	reads (list_issues/get_file_contents)	data returned	ALLOWED	✅
D	CLI	REST writes (reaction/star/issue/comment/file)	unauthenticated	BLOCKED	⚠️
E	CLI	GraphQL mutations (addReaction/addStar/createIssue)	unauthenticated	BLOCKED	⚠️

Overall: INCONCLUSIVE

⚠️ Part B: All 7 write tool targets absent from the 23-tool read-only catalog (unknown tool [-32602]). No write succeeded. Gap: GITHUB_READ_ONLY=1 in gh-aw prevents backend from registering write tools — this is defense-in-depth by the framework, not confirmed mcpg-level DIFC enforcement for this surface. Covered by internal/guard and internal/difc unit tests.

⚠️ Parts D/E: gh is not authenticated in this environment (gh auth status: not logged into any host). REST and GraphQL write attempts were not executed — token-scope boundary cannot be validated in this run.

No writes leaked. No test artifacts created.

🔒 mcpg read-only stress (gVisor runtime) by Read-Only Stress: gVisor runtime

[github-actions]

🔒 mcpg Read-Only Stress — docker-sbx

Surface coverage: MCP tool calls + proxied CLI (REST) + GraphQL mutations
Isolation runtime: docker-sbx (KVM-isolated microVM)

Part	Surface	Op	Result	Expected	Status
A	MCP	reads (issues/PRs/file/commits)	data returned	ALLOWED	✅
B	MCP	writes (reaction/star/issue/comment/branch/file/PR)	all absent from catalog	BLOCKED	⚠️
C	CLI	reads (list_issues, get_file_contents)	data returned	ALLOWED	✅
D	CLI	REST writes (reaction/star/issue/comment/file)	unauthenticated (401)	BLOCKED	⚠️
E	CLI	GraphQL mutations (addReaction/addStar/createIssue)	unauthenticated (401)	BLOCKED	⚠️

Overall: INCONCLUSIVE

⚠️ Gap 1 (Part B): All 23 MCP tools exposed are read-only; zero write tools appear in the catalog. This is because gh-aw unconditionally sets GITHUB_READ_ONLY=1, so write tools are never registered by the backend. Every write attempt returned Error [-32602]: unknown tool. This confirms the backend defense-in-depth guarantee but does not independently exercise mcpg's own DIFC/guard enforcement layer — gateway-level write blocking via DIFC/guard cannot be confirmed on this surface.

⚠️ Gap 2 (Parts D & E): gh CLI is unauthenticated in this environment (GH_TOKEN invalid — 401 Bad credentials). All Part D/E write attempts returned 401 due to missing credentials, not gateway enforcement. The token-scope boundary cannot be validated this run.

No write leaked. No FAIL condition triggered.

Run: §33342894608

🔒 mcpg read-only stress (docker-sbx runtime) by Read-Only Stress: docker-sbx runtime

[github-actions]

🔒 mcpg Read-Only Stress — default AWF

Surface coverage: MCP tool calls + proxied CLI (REST) + GraphQL mutations
Isolation runtime: default AWF (normal container isolation)

Part	Surface	Op	Result	Expected	Status
A	MCP	list_issues	issues #12226, #12225, #12224 returned	ALLOWED	✅
A	MCP	list_pull_requests	data returned	ALLOWED	✅
A	MCP	get_file_contents README.md	file content returned	ALLOWED	✅
A	MCP	list_commits	commits returned	ALLOWED	✅
B	MCP	writes (reaction/star/issue/comment/branch/file/PR)	all tools absent from catalog	BLOCKED	⚠️
C	CLI	list_issues (github CLI → gateway)	data returned	ALLOWED	✅
C	CLI	get_file_contents README.md	data returned	ALLOWED	✅
D	CLI	REST writes (reaction/star/issue/comment/file)	unauthenticated	BLOCKED	⚠️
E	CLI	GraphQL mutations (addReaction/addStar/createIssue)	unauthenticated	BLOCKED	⚠️

Overall: INCONCLUSIVE

⚠️ Part B: All 7 write tools (add_issue_comment, star_repository, issue_write, create_branch, create_or_update_file, create_pull_request) are absent from the MCP tool catalog (23 tools exposed, all read-only). This is the expected result of GITHUB_READ_ONLY=1 set by the gh-aw framework, which prevents the backend from registering write tools at all. This confirms the backend defense-in-depth guarantee but does not independently confirm mcpg's own DIFC/guard enforcement layer — that enforcement surface would require a write-capable backend, which is structurally unavailable in this workflow.

⚠️ Parts D/E: gh CLI is not authenticated (GH_TOKEN not set) in this environment. All REST/GraphQL write attempts return a gh auth error, not a GitHub API 403 from a read-only token. Therefore token-scope write-blocking cannot be confirmed for this run.

No writes leaked. Run is INCONCLUSIVE (not FAIL) per the validation criteria.

🔒 mcpg read-only stress (default AWF runtime) by Read-Only Stress: default runtime