finfocus: Skill for Claude Code

FinFocus Development Workflow

Quick Reference

make build          # Build binary to bin/finfocus
make test           # Unit tests (fast, default)
make lint           # golangci-lint + markdownlint (5+ min, use extended timeout)
make validate       # go mod tidy + go vet
make test-race      # Race detector
make test-integration  # Cross-component tests (10min timeout)
make build-all      # Build binary + all plugins

Critical rules: Always run make lint and make test before claiming success. Never run git commit (user commits manually). Never modify .golangci.yml.

Adding a CLI Command

1. Create internal/cli/your_command.go
2. Follow constructor pattern:

func NewYourCmd() *cobra.Command {
    var flagVar string
    cmd := &cobra.Command{
        Use:   "your-command",
        Short: "Description",
        RunE: func(cmd *cobra.Command, args []string) error {
            // Use cmd.Printf() not fmt.Printf()
            return nil
        },
    }
    cmd.Flags().StringVar(&flagVar, "flag", "", "description")
    return cmd
}

1. Register in parent command (e.g., root.go or cost.go)
2. Use RunE (not Run) for error handling
3. Defer cleanup immediately: defer cleanup()

Resource Processing Pipeline

All cost commands follow:

ingest.LoadPulumiPlan(path) -> ingest.MapResources() -> registry.Open(ctx, adapter)
  -> engine.GetProjectedCost/GetActualCost() -> engine.RenderResults(format, results)

Testing Standards

• Use testify/assert and testify/require exclusively (never manual if/t.Errorf)
• require.* for setup that must succeed; assert.* for value checks
• Table-driven tests for variations
• Package suffix _test for black-box testing
• t.TempDir() for temporary files (auto-cleanup)
• Capture output: cmd.SetOut(&buf) and cmd.SetErr(&buf)
• Target 80% coverage minimum, 95% for critical paths

See references/testing-patterns.md for detailed test patterns and examples.