package exec

import (
	"context"
	"testing"
)

// mockProvider is a configurable Provider used to prove the interface can be
// mocked. It mocks the interface, not a concrete type, per the test
// conventions.
type mockProvider struct {
	execute func(ctx context.Context, req ExecRequest) (*ExecResult, error)
}

func (m mockProvider) Execute(ctx context.Context, req ExecRequest) (*ExecResult, error) {
	if m.execute == nil {
		return &ExecResult{}, nil
	}
	return m.execute(ctx, req)
}

// TestProvider_InterfaceConformance is a compile-time assertion that both the
// mock and the real executor satisfy Provider.
func TestProvider_InterfaceConformance(t *testing.T) {
	t.Parallel()
	var _ Provider = mockProvider{}
	var _ Provider = (*TerminalExecutor)(nil)
}

// TestProvider_MockRoundTrip exercises the interface through a mock without any
// real process.
func TestProvider_MockRoundTrip(t *testing.T) {
	t.Parallel()
	var got ExecRequest
	p := mockProvider{execute: func(ctx context.Context, req ExecRequest) (*ExecResult, error) {
		got = req
		return &ExecResult{Stdout: "ok"}, nil
	}}

	res, err := p.Execute(context.Background(), ExecRequest{Command: []string{"echo", "hi"}})
	if err != nil {
		t.Fatalf("Execute error: %v", err)
	}
	if res.Stdout != "ok" {
		t.Errorf("Stdout = %q, want ok", res.Stdout)
	}
	if len(got.Command) != 2 || got.Command[0] != "echo" {
		t.Errorf("got.Command = %v, want [echo hi]", got.Command)
	}
}