address comments

Author: ymqytw

exec/exec.go

@@ -26,7 +26,7 @@ import (
 // ErrExecutableNotFound is returned if the executable is not found.
 var ErrExecutableNotFound = osexec.ErrNotFound
 
-// Interface is an interface that presents a subset of the os/exec API.  Use this
+// Interface is an interface that presents a subset of the os/exec API. Use this
 // when you want to inject fakeable/mockable exec behavior.
 type Interface interface {
 	// Command returns a Cmd instance which can be used to run a single command.
@@ -38,13 +38,13 @@ type Interface interface {
 }
 
 // Cmd is an interface that presents an API that is very similar to Cmd from os/exec.
-// As more functionality is needed, this can grow.  Since Cmd is a struct, we will have
+// As more functionality is needed, this can grow. Since Cmd is a struct, we will have
 // to replace fields with get/set method pairs.
 type Cmd interface {
 	// Run runs the command to the completion.
 	Run() error
 	// CombinedOutput runs the command and returns its combined standard output
-	// and standard error.  This follows the pattern of package os/exec.
+	// and standard error. This follows the pattern of package os/exec.
 	CombinedOutput() ([]byte, error)
 	// Output runs the command and returns standard output, but not standard err
 	Output() ([]byte, error)
@@ -60,7 +60,7 @@ type Cmd interface {
 }
 
 // ExitError is an interface that presents an API similar to os.ProcessState, which is
-// what ExitError from os/exec is.  This is designed to make testing a bit easier and
+// what ExitError from os/exec is. This is designed to make testing a bit easier and
 // probably loses some of the cross-platform properties of the underlying library.
 type ExitError interface {
 	String() string
@@ -90,6 +90,8 @@ func (executor *executor) LookPath(file string) (string, error) {
 // Wraps exec.Cmd so we can capture errors.
 type cmdWrapper osexec.Cmd
 
+var _ Cmd = &cmdWrapper{}
+
 func (cmd *cmdWrapper) SetDir(dir string) {
 	cmd.Dir = dir
 }

exec/testing/fake_exec.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package exec
+package testingexec
 
 import (
 	"fmt"
@@ -60,6 +60,8 @@ type FakeCmd struct {
 	Stderr               io.Writer
 }
 
+var _ exec.Cmd = &FakeCmd{}
+
 func InitFakeCmd(fake *FakeCmd, cmd string, args ...string) exec.Cmd {
 	fake.Argv = append([]string{cmd}, args...)
 	return fake
@@ -130,6 +132,8 @@ type FakeExitError struct {
 	Status int
 }
 
+var _ exec.ExitError = FakeExitError{}
+
 func (fake *FakeExitError) String() string {
 	return fmt.Sprintf("exit %d", fake.Status)
 }