clawker: Skill for Claude Code

writing-tests

Extended test patterns and examples. For the mandatory rules, see the Testing rules section of the root AGENTS.md.

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Testing Philosophy: DAG-Driven Test Infrastructure

The Core Principle

Clawker's packages follow a strict DAG (Directed Acyclic Graph):

┌─────────────┐     ┌─────────────┐     ┌─────────────┐     ┌─────────────┐
│ Foundation  │ ──▶ │   Middle    │ ──▶ │  Composite  │ ──▶ │  Commands   │
│  Packages   │     │  Packages   │     │  Packages   │     │             │
├─────────────┤     ├─────────────┤     ├─────────────┤     ├─────────────┤
│ git, logger │     │ bundler     │     │ docker,     │     │ cmd/*       │
│ iostreams   │     │             │     │ workspace   │     │             │
│ config      │     │             │     │             │     │             │
└─────────────┘     └─────────────┘     └─────────────┘     └─────────────┘
       │                                       │                   │
       ▼                                       ▼                   ▼
   gittest/                               docker/mocks/       Factory DI
   config/mocks/                          whailtest/          + runF seam

Each node in the DAG must provide test infrastructure for its dependents.

When every node provides fakes/mocks/stubs, any tier can independently test by mocking the entire chain below it.

Test Seams in Clawker

1. Factory Pattern DI

Factory fields are closures that return dependencies. Tests inject fakes:

f := &cmdutil.Factory{
    IOStreams: tio,
    Client: func(ctx context.Context) (*docker.Client, error) {
        return fake.Client, nil  // Fake from docker/mocks
    },
    Config: func() (config.Config, error) {
        return configmocks.NewBlankConfig(), nil
    },
    // ... other fields
}

2. runF Test Seam

Every command constructor accepts runF to intercept execution:

// Tier 1: Flag parsing only (intercept before run)
var captured *RunOptions
cmd := NewCmdRun(f, func(ctx context.Context, opts *RunOptions) error {
    captured = opts
    return nil  // Don't actually run
})

// Tier 2: Full execution with injected deps
cmd := NewCmdRun(f, nil)  // nil = real run function with Factory's fakes