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google/capsem/dev-testing-vm

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version: "1.0.0" name: dev-testing-vm description: In-VM diagnostics and test fixtures for Capsem. Use when working with capsem-doctor, adding new in-VM tests, debugging test failures inside the guest, inspecting session databases, or updating the test fixture. Covers the full capsem-doctor test suite, how to run subsets, how to add new VM tests, session inspection, and fixture management.

In-VM Testing

capsem-doctor

The diagnostic suite runs inside the guest VM via pytest. Tests live in guest/artifacts/diagnostics/ and are baked into the rootfs.

Running diagnostics

bash

just run "capsem-doctor"              # Full suite (~10s total)
just run "capsem-doctor -k sandbox"   # Only sandbox tests
just run "capsem-doctor -k network"   # Only network tests
just run "capsem-doctor -x"           # Stop on first failure

Test categories

File	What it verifies
`test_sandbox.py`	Read-only rootfs, binary permissions, setuid/setgid, kernel hardening (no modules, no debugfs, no IPv6, no swap), process integrity, network isolation (dummy0, fake DNS, iptables)
`test_network.py`	MITM CA in system store + certifi, curl without -k, Python urllib HTTPS, CA env vars, HTTP/80 blocked, non-443 blocked, direct IP blocked, multi-domain DNS, AI provider domains
`test_environment.py`	TERM/HOME/PATH env vars, bash shell, kernel version, aarch64 arch, mount points, tmpfs
`test_runtimes.py`	Python3, Node.js, npm, pip3, git version checks, Python/Node file I/O, git workflow
`test_utilities.py`	~36 unix utilities (coreutils, text processing, network, system tools)
`test_workflows.py`	Text write/read, JSON roundtrip, shell pipes, large file (10MB)
`test_ai_cli.py`	claude/gemini/codex installed and executable
`test_virtiofs.py`	VirtioFS mount, ext4 loopback, workspace I/O, pip install, file delete+recreate

Adding new in-VM tests

Add test functions to the appropriate guest/artifacts/diagnostics/test_*.py or create test_<category>.py
Use from conftest import run for shell commands, output_dir fixture for temp files
Tests auto-skip outside the capsem VM (conftest checks for root + writable /root)
Rebuild rootfs with just build-assets to bake new test files into the image
For fast iteration during development, tests in diagnostics/ are also repacked into the initrd by just run, so just run "capsem-doctor" picks up changes without a full rootfs rebuild
Verify: just run "capsem-doctor -k <your_test>"

Session inspection

After running a VM session, inspect the telemetry database:

bash

just inspect-session              # Latest session
just inspect-session <session-id> # Specific session
just inspect-session --list       # List recent sessions
just inspect-session -n 10        # Show 10 preview rows per table

Checks: all 6 tables exist (net_events, model_calls, tool_calls, tool_responses, mcp_calls, fs_events), row counts, orphaned tool_calls, AI-provider consistency.

Verifying telemetry pipelines

Each pipeline can be tested with a targeted VM command:

fs_events: just run 'touch /root/test.txt && sleep 1' then just inspect-session
net_events: just run 'curl -s https://api.anthropic.com/ && sleep 1'
model_calls/tool_calls: boot interactively, run claude -p "what is 2+2"
mcp_calls: boot interactively, run claude -p "use fetch to get https://example.com"

If events are missing: check boot logs for daemon startup, vsock connection acceptance, and whether the VM lived long enough for the debouncer to flush (add sleep 1).

Test fixture

The fixture (data/fixtures/test.db) is a real session DB shared by frontend mock mode and Rust roundtrip tests. No synthetic data.

Updating the fixture

bash

# 1. Run integration test to generate a rich session
python3 scripts/integration_test.py --binary target/debug/capsem --assets assets
 
# 2. Inspect completeness
just inspect-session <session-id>
 
# 3. Update (scrubs API keys, copies to both data/ and frontend/)
just update-fixture ~/.capsem/sessions/<id>/session.db
 
# 4. Verify
cargo test --workspace

The fixture must contain: both allowed and denied net_events, created/modified/deleted fs_events, model_calls with cost > 0, tool_calls with origin populated.

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