Comprehensive test suite

[castrojo]

Description

Implement a comprehensive test suite covering all internal packages. The strategy prioritizes determinism (no real hardware, no real network), speed (table-driven unit tests), and confidence (golden files catch config regressions).

Interfaces Required (define before writing tests)

// internal/runner/runner.go
type Runner interface {
    Run(ctx context.Context, name string, args ...string) (Output, error)
}
type Output struct { Stdout, Stderr string; ExitCode int }

// internal/bakery/client.go
type HTTPClient interface {
    Do(req *http.Request) (*http.Response, error)
}

// internal/probe/prober.go
type DiskProber interface { ListDisks(ctx context.Context) ([]Disk, error) }
type NetworkProber interface { ListInterfaces(ctx context.Context) ([]Interface, error) }

// internal/install/installer.go
type Installer interface { Install(ctx context.Context, config InstallConfig) error }

Per-Package Test Plan

internal/runner

• TestRunner_Execute_ReturnsStdout — captures stdout from real command
• TestRunner_Execute_ReturnsStderr — captures stderr separately
• TestRunner_Execute_NonZeroExit — returns structured error with exit code
• TestRunner_DryRun_LogsCommand — dry-run records command without executing
• TestRunner_DryRun_DoesNotMutateSystem — no side effects
• TestRunner_Execute_Timeout — context cancellation kills child process
• TestRunner_Execute_BinaryNotFound — wraps exec.ErrNotFound
• TestRunner_CommandLog_OrderPreserved — dry-run log order

internal/probe

• TestProbe_Disks_ParsesLsblkJSON — parses fixture (NVMe, SATA, USB)
• TestProbe_Disks_FiltersByType — excludes loop, rom, lvm
• TestProbe_Disks_EmptyOutput — no disks → empty slice, no error
• TestProbe_Disks_MalformedJSON — returns parse error
• TestProbe_Disks_ByIDPath — maps /dev/sda → /dev/disk/by-id/...
• TestProbe_Network_ParsesIPLink — parses fixture (eth0, wlan0, lo)
• TestProbe_Network_FiltersLoopback — excludes lo
• TestProbe_Network_NoInterfaces — returns empty, no error

internal/bakery

• TestBakery_FetchCatalog_Success — parses valid catalog JSON (httptest)
• TestBakery_FetchCatalog_HTTPError — 404/500 returns typed error
• TestBakery_FetchCatalog_Timeout — context deadline exceeded
• TestBakery_FetchCatalog_MalformedJSON — decode error with body prefix
• TestBakery_FetchCatalog_EmptyCatalog — zero sysexts is valid
• TestBakery_FilterByArch_AMD64 — filters entries by architecture
• TestBakery_SysextURL_Constructs — builds download URL from entry

internal/ignition (golden file tests)

• TestIgnition_Assemble_MinimalConfig — hostname + disk → valid Butane
• TestIgnition_Assemble_WithSSHKeys — SSH keys in passwd section
• TestIgnition_Assemble_WithSysexts — sysext units and downloads
• TestIgnition_Assemble_WithStaticIP — network unit rendered
• TestIgnition_Assemble_FlatcarVariant — output contains variant: flatcar
• TestIgnition_Compile_GoldenMinimal — golden file comparison
• TestIgnition_Compile_GoldenFull — golden file comparison (all options)
• TestIgnition_ExternalURL_Passthrough — URL mode skips local generation
• TestIgnition_ExternalURL_MutualExclusion — URL + local → validation error

internal/validate (table-driven)

• TestValidate_Hostname_Valid / _Empty / _TooLong / _InvalidChars
• TestValidate_IPv4_ValidCIDR / _InvalidCIDR / _OutOfRange
• TestValidate_Gateway_ValidIPv4 / _WithCIDR / _OutsideSubnet
• TestValidate_SSHKey_ValidEd25519 / _ValidRSA / _Empty / _MalformedPrefix
• TestValidate_DiskPath_ValidByID / _RawDevice / _NonExistent
• TestValidate_ConfigConsistency_StaticIPRequiresGateway
• TestValidate_ConfigConsistency_DHCPIgnoresStaticFields

internal/wizard (state machine)

• TestWizard_InitialState — starts at step 0
• TestWizard_Next_AdvancesStep / _BlockedByValidation
• TestWizard_Back_DecrementsStep / _AtFirstStep
• TestWizard_Summary_AllFields — shows all collected data
• TestWizard_Confirm_TriggersInstall — invokes install
• TestWizard_ExternalURL_SkipsConfigSteps
• TestWizard_StateTransitions_Full — complete happy path

internal/install

• TestInstall_Execute_HappyPath — correct flatcar-install args
• TestInstall_Execute_DryRun — logs without execution
• TestInstall_Execute_DiskByID — uses /dev/disk/by-id/ path
• TestInstall_Execute_CommandFailure — wraps runner error
• TestInstall_Execute_MissingBinary — clear error message

cmd/knuckle

• TestCLI_DryRunFlag_SetsRunner
• TestCLI_VersionFlag_Prints
• TestCLI_HelpFlag_ShowsUsage
• TestCLI_InvalidFlag_Exits1

Test Fixtures (testdata/)

testdata/
├── probe/
│   ├── lsblk_nvme_sata_usb.json       # Mixed disk types
│   ├── lsblk_single_nvme.json         # Single NVMe
│   ├── lsblk_empty.json               # No blockdevices
│   ├── lsblk_with_loops.json          # Loop devices to filter
│   ├── lsblk_malformed.json           # Truncated JSON
│   ├── ip_link_eth_wlan.json          # Multiple interfaces
│   ├── ip_link_single_eth.json        # Single wired NIC
│   └── ip_link_empty.json             # No interfaces
├── bakery/
│   ├── catalog_full.json              # Complete sysext catalog
│   ├── catalog_empty.json             # Empty array
│   └── catalog_malformed.json         # Invalid JSON
├── ignition/golden/
│   ├── minimal.ign                    # Hostname + disk + SSH key
│   ├── full.ign                       # All options
│   ├── static_ip.ign                  # Static network
│   ├── sysexts.ign                    # With extensions
│   └── dhcp.ign                       # DHCP networking
└── install/
    └── flatcar_install_help.txt       # For arg verification

Critical Edge Cases

• Disk with no serial → by-id path construction fails gracefully
• SSH key with YAML special chars (#, :) → no YAML injection in Butane
• IPv6 when only IPv4 expected → wrong address family rejected
• CIDR /0 or /32 → technically valid but flagged as suspicious
• Gateway outside subnet → config is syntactically valid but won't route
• Catalog response >10MB → enforce read limit (DoS protection)
• Rapid back/next in wizard → no state corruption
• No disks found → error screen, no crash
• Sysext name with URL-unsafe chars → URL encoding in download path

Coverage Targets

Package	Target
internal/validate	≥80%
internal/ignition	≥80%
internal/probe	≥80%
internal/runner	≥80%
internal/bakery	≥70%
internal/install	≥70%
internal/wizard	≥60%

Implementation Priority

1. internal/validate — pure functions, highest immediate value
2. internal/runner — foundation; mock must work for all other tests
3. internal/probe — fixture-driven, catches parsing regressions
4. internal/ignition — golden files catch config regressions (machine-bricking risk)
5. internal/bakery — httptest pattern
6. internal/install — depends on runner mock
7. internal/wizard — integration-heavy, depends on all mocks
8. cmd/knuckle — thin layer, lowest risk

Build Tags & Running

go test ./...                           # Unit tests only (fast)
go test -tags=integration ./...         # Include integration tests
go test ./internal/ignition -update     # Regenerate golden files
go test -race ./...                     # Race detector for wizard state

Acceptance Criteria

• Every package has _test.go with listed test functions
• go test ./... passes with zero failures
• go test -race ./... passes (no data races)
• Golden files exist and -update flag works
• Test fixtures committed (not generated at test time)
• Interfaces defined and used in production code
• Mock implementations for all interfaces
• Coverage meets targets above
• Integration tests gated behind //go:build integration
• No test depends on network, real disks, or root privileges
• CI runs go test -race ./... on every push