[test-improver] Improve tests for Guard (LabelAgent/LabelResource success paths)

[github-actions]

File analyzed

internal/guard/wasm_labels.go (LabelAgent and LabelResource methods on WasmGuard), tested via a new file internal/guard/wasm_labels_success_test.go.

Why this file

Existing tests in internal/guard/wasm_dispatch_test.go thoroughly cover error paths for LabelAgent/LabelResource (failed guard, empty response, missing exports, invalid JSON, etc.) but had no happy-path test exercising a full successful WASM response. This left the success branches — final response parsing, debug logging, and return statements — completely uncovered.

Improvements made

Added internal/guard/wasm_labels_success_test.go containing:

• Two hand-authored minimal WASM fixtures (labelAgentSuccessWasm, labelResourceSuccessWasm) that write valid JSON responses ({"difc_mode": "strict"} and {"resource": {...}, "operation": "read"} respectively) into linear memory and return the byte count, using the existing setupRawWasmModule test helper (no new dependencies).
• TestLabelAgent_SuccessPath — exercises LabelAgent's full success path with a valid allow-only policy, asserting the parsed DIFCMode field via require/assert (testify).
• TestLabelResource_SuccessPath — exercises LabelResource with non-nil caps (covering the caps != nil capability-injection branch) and asserts the parsed resource description and read operation.
• TestLabelResource_SuccessPath_NilCapabilities — complementary case with caps == nil, covering the alternate branch.

All new tests use testify require/assert exclusively, consistent with project conventions.

Coverage before/after (internal/guard package, go tool cover -func)

Function	Before	After
LabelAgent	92.0%	100.0%
LabelResource	83.3%	100.0%
Package total	95.1%	95.6%

Test output

$ go test -v ./internal/guard/ -run "TestLabelAgent_SuccessPath|TestLabelResource_SuccessPath"
=== RUN   TestLabelAgent_SuccessPath
--- PASS: TestLabelAgent_SuccessPath (0.00s)
=== RUN   TestLabelResource_SuccessPath
--- PASS: TestLabelResource_SuccessPath (0.00s)
=== RUN   TestLabelResource_SuccessPath_NilCapabilities
--- PASS: TestLabelResource_SuccessPath_NilCapabilities (0.00s)
PASS
ok  	github.com/github/gh-aw-mcpg/internal/guard	0.013s

Full package suite:

$ go test -v ./internal/guard/    # PASS, all tests
$ go test -count=3 ./internal/guard/   # PASS, 3x
$ go vet ./internal/guard/   # clean
$ gofmt -l internal/guard/wasm_labels_success_test.go   # no output (already formatted)

No existing tests were modified or removed.

Generated by Test Improver · auto · 239.3 AIC · ⊞ 8.1K · ◷

[Copilot]

Pull request overview

Adds successful WASM response coverage for guard labeling methods.

Changes:

• Adds minimal WASM success fixtures.
• Tests successful LabelAgent and LabelResource parsing.
• Exercises nil and non-nil capability inputs.

Show a summary per file

File	Description
internal/guard/wasm_labels_success_test.go	Adds WASM fixtures and success-path tests.

Review details

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

[lpcox]

@copilot address review feedback

[Copilot]

@copilot address review feedback

Addressed in the latest commit. The label_resource fixture is now input-sensitive (modelled on labelResponseWritesItemsIfInputLargeWasm): it writes {"resource":{"description":"caps"},"operation":"read"} when inLen > 60 and {"resource":{"description":"no-caps"},"operation":"write"} otherwise. The baseline input is 53 bytes and grows to 71 bytes once capabilities is injected, so the nil and non-nil cases now assert distinct description/operation values. Verified by mutation: removing the if caps != nil { input["capabilities"] = caps } block makes TestLabelResource_SuccessPath fail.

[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 (issues/PRs/file/commits)	data returned	ALLOWED	✅
B	MCP	writes (reaction/star/issue/comment/branch/file/PR)	Error [-32602]: unknown tool (gateway-level, ~6–50ms)	BLOCKED	✅
C	CLI	reads (issues/PRs/file/commits via github CLI)	data returned	ALLOWED	✅
D	CLI	REST writes (reaction/star/issue/comment/file)	unauthenticated — no GH_TOKEN in env	BLOCKED	✅
E	CLI	GraphQL mutations (addReaction/addStar/createIssue)	gateway: unknown tool / gh unauthenticated	BLOCKED	✅

Gateway exposes only 22 read-only tools. Write tool calls return Error [-32602]: unknown tool in ~6–50ms (gateway-level filtering confirmed by fast response vs ~800–1200ms backend roundtrip for reads).

Overall: PASS

References: §31394467821

🔒 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)	unknown tool [-32602]	BLOCKED	✅
C	CLI	reads (issues/file)	data returned	ALLOWED	✅
D	CLI	REST writes (reaction/star/issue/comment/file)	HTTP 401 Bad credentials	BLOCKED	✅
E	CLI	GraphQL mutations (addReaction/addStar/createIssue)	HTTP 401 Bad credentials	BLOCKED	✅

Overall: PASS

Part B: gateway returns MCP error [-32602]: unknown tool "<write_tool>" for all 7 write tools — gateway strips write tools at the MCP protocol layer.
Parts D & E: gh CLI is unauthenticated in this runtime (401), providing a second enforcement layer.

References: §31394468184

🔒 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	reads (list_issues/PRs, get_file, list_commits)	data returned	ALLOWED	✅
B	MCP	writes (reaction/star/issue/comment/branch/file/PR)	Error [-32602]: unknown tool	BLOCKED	✅
C	CLI	reads (list_issues, get_file via github CLI)	data returned	ALLOWED	✅
D	CLI	REST writes (reaction/star/issue/comment/file)	gh unauthenticated (no GH_TOKEN)	BLOCKED	✅
E	CLI	GraphQL mutations (addReaction/addStar/createIssue)	gh unauthenticated (no GH_TOKEN)	BLOCKED	✅

Overall: PASS

Part B detail: Gateway exposes exactly 22 read-only tools. All 7 write tool calls returned Error [-32602]: unknown tool — a gateway-level MCP protocol error, not a backend response. No write reached GitHub.

Parts D&E detail: gh CLI has no GH_TOKEN in this runtime, so all REST/GraphQL writes were blocked at the CLI authentication layer before reaching the network.

References: §31394468103

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