Implement the debug flag and help command

I'm vacillating about the choice to have separate Config structs in the
`helm` and `run` packages. I can't tell whether it's "good separation of
concerns" or "cumbersome and over-engineered." It seems appropriate at
the moment, though.

internal/run/help_test.go

@@ -1,33 +1,72 @@
 package run
 
 import (
+	"fmt"
 	"github.com/golang/mock/gomock"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/suite"
+	"strings"
 	"testing"
 )
 
-func TestHelp(t *testing.T) {
-	ctrl := gomock.NewController(t)
+type HelpTestSuite struct {
+	suite.Suite
+}
+
+func TestHelpTestSuite(t *testing.T) {
+	suite.Run(t, new(HelpTestSuite))
+}
+
+func (suite *HelpTestSuite) TestPrepare() {
+	ctrl := gomock.NewController(suite.T())
 	defer ctrl.Finish()
 
 	mCmd := NewMockcmd(ctrl)
 	originalCommand := command
 
 	command = func(path string, args ...string) cmd {
-		assert.Equal(t, helmBin, path)
-		assert.Equal(t, []string{"help"}, args)
+		assert.Equal(suite.T(), helmBin, path)
+		assert.Equal(suite.T(), []string{"help"}, args)
 		return mCmd
 	}
 	defer func() { command = originalCommand }()
 
+	stdout := strings.Builder{}
+	stderr := strings.Builder{}
+
 	mCmd.EXPECT().
-		Stdout(gomock.Any())
+		Stdout(&stdout)
 	mCmd.EXPECT().
-		Stderr(gomock.Any())
+		Stderr(&stderr)
 	mCmd.EXPECT().
 		Run().
 		Times(1)
 
-	h := NewHelp()
-	h.Run()
+	cfg := Config{
+		Stdout: &stdout,
+		Stderr: &stderr,
+	}
+
+	h := Help{}
+	err := h.Prepare(cfg)
+	suite.Require().Nil(err)
+	h.Execute()
+}
+
+func (suite *HelpTestSuite) TestPrepareDebugFlag() {
+	help := Help{}
+
+	stdout := strings.Builder{}
+	stderr := strings.Builder{}
+	cfg := Config{
+		Debug:  true,
+		Stdout: &stdout,
+		Stderr: &stderr,
+	}
+
+	help.Prepare(cfg)
+
+	want := fmt.Sprintf("Generated command: '%s --debug help'\n", helmBin)
+	suite.Equal(want, stderr.String())
+	suite.Equal("", stdout.String())
 }