Jan Novak
a9534ec2c1
Extract run(args, stdout, stderr) int from main() for in-process testability. Fix TLS failure classification (tlsErr now captured from TLSHandshakeDone hook). Add run_test.go with 14 table-driven in-process tests and cli_test.go with TestMain + 3 subprocess smoke tests. All servers use httptest; .invalid TLD for deterministic DNS failures. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
91 lines
3.6 KiB
Markdown
91 lines
3.6 KiB
Markdown
# Step 6 — Integration Tests
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## What this step delivers
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A full integration-test suite covering every success and failure mode of the
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`latprobe` CLI. Tests are written using the Go standard library only (`testing`,
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`net/http/httptest`, `os/exec`, `encoding/json`) — no third-party dependencies.
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Two test layers:
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| Layer | File | How it runs |
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|-------|------|-------------|
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| In-process | `go/run_test.go` | Calls `run(args, stdout, stderr)` directly; fast, covers the full matrix |
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| Subprocess | `go/cli_test.go` | Builds the real binary once, `exec.Command`s it; exercises the true `os.Exit` path |
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## Running the tests
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```sh
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cd go
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# Run all tests (quiet)
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go test ./...
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# Run with per-case output
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go test -v ./...
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# Run only in-process tests
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go test -v -run TestRunMatrix .
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go test -v -run TestJSON .
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# Run only subprocess smoke tests
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go test -v -run TestCLI .
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```
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## Test matrix
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### In-process (`run_test.go`)
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| Test case | Exit code | Assertion |
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|-----------|-----------|-----------|
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| Success 200 | 0 | stdout contains `(200)`, `TCP connect`, `Total` |
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| HTTP 500, no `--fail` | 0 | stdout contains `(500)`, `Total` |
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| HTTP 404, `--fail` | 6 | stdout contains `404 ✗` |
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| DNS failure (`.invalid` TLD) | 2 | stdout contains `✗ dns:` |
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| Connection refused (listen-then-close) | 3 | stdout contains `✗ connect:` |
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| Timeout (`--timeout 200ms`, blocking handler) | 4 | stdout contains `✗ timeout:` |
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| TLS failure (self-signed cert) | 5 | stdout contains `✗ tls:` |
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| Multiple URLs (200 + `.invalid`) | 2 (highest) | stdout contains both `(200)` and `✗ dns:` |
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| Sampling `-n 3`, all success | 0 | stdout contains `3 samples`, `min`, `avg`, `max` |
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| No args | 1 | stderr contains `Usage:` |
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| `-h` | 0 | stderr contains `Usage:` |
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| `--json` success | 0 | valid JSON, `phases.total` present, `failed == 0` |
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| `--json` DNS failure | 2 | valid JSON, `errors[0].phase == "dns"`, `succeeded == 0` |
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| `--json` `-n 3` success | 0 | `succeeded == 3`, `total.min_ms > 0`, `max_ms >= min_ms` |
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### Subprocess smoke tests (`cli_test.go`)
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`TestMain` builds the binary with `go build -o <tmp>/latprobe .` once before
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any test runs. The binary is deleted on test completion.
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| Test | Checks |
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|------|--------|
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| `TestCLISuccess` | Local server, exit 0, stdout has `(200)` and `Total` |
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| `TestCLIDNSFailure` | `.invalid` host, real binary exits 2 |
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| `TestCLIJSONDNSFailure` | `.invalid` host, JSON output, `errors[0].phase == "dns"` |
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## Notes
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- The `http: TLS handshake error` log line printed during the TLS test is the
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**server-side** log of the client correctly rejecting the self-signed cert.
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It is expected and harmless.
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- `httptest.NewServer` binds to `127.0.0.1`; Go resolves loopback addresses
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without a DNS query, so the DNS row does not appear in localhost test output.
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Tests use `TCP connect` as the success-path phase assertion instead.
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- The test suite requires no network access for any case except DNS failure,
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which uses the reserved `.invalid` TLD (RFC 6761 — always NXDOMAIN).
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## Code changes included in this step
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Beyond the tests, two code changes were made:
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1. **`main.go` refactor** — extracted `run(args []string, stdout, stderr io.Writer) int`
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so the CLI is testable in-process. `main()` is now a one-liner:
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`os.Exit(run(os.Args[1:], os.Stdout, os.Stderr))`. No behaviour change.
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2. **`probe.go` TLS classification fix** — Go's `httptrace` calls
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`TLSHandshakeDone` with the error on a failed handshake, so `tlsDone` was
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set even on cert rejection. The previous classifier ("tlsStart set, tlsDone
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zero") never matched. Fixed by capturing `tlsErr` from the hook and checking
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it in `classifyErr`.
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