Now that we have a testutil package, put ioutil.go into it

Signed-off-by: Ryan Richard <richardry@vmware.com>

cmd/placeholder-name/main_test.go

@@ -9,10 +9,11 @@ import (
 	"bytes"
 	"context"
 	"fmt"
-	"io"
 	"testing"
 	"time"
 
+	"github.com/suzerain-io/placeholder-name/internal/testutil"
+
 	"github.com/sclevine/spec"
 	"github.com/sclevine/spec/report"
 	"github.com/stretchr/testify/require"
@@ -20,15 +21,6 @@ import (
 	"github.com/suzerain-io/placeholder-name/pkg/client"
 )
 
-// errorWriter implements io.Writer by returning a fixed error.
-type errorWriter struct {
-	returnError error
-}
-
-var _ io.Writer = &errorWriter{}
-
-func (e *errorWriter) Write([]byte) (int, error) { return 0, e.returnError }
-
 func TestRun(t *testing.T) {
 	spec.Run(t, "main.run", func(t *testing.T, when spec.G, it spec.S) {
 		var r *require.Assertions
@@ -95,7 +87,7 @@ func TestRun(t *testing.T) {
 			})
 
 			it("returns an error", func() {
-				err := run(envGetter, tokenExchanger, &errorWriter{returnError: fmt.Errorf("some IO error")}, 30*time.Second)
+				err := run(envGetter, tokenExchanger, &testutil.ErrorWriter{ReturnError: fmt.Errorf("some IO error")}, 30*time.Second)
 				r.EqualError(err, "failed to marshal response to stdout: some IO error")
 			})
 		})

internal/testutil/ioutil.go

@@ -0,0 +1,17 @@
+/*
+Copyright 2020 VMware, Inc.
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package testutil
+
+import "io"
+
+// ErrorWriter implements io.Writer by returning a fixed error.
+type ErrorWriter struct {
+	ReturnError error
+}
+
+var _ io.Writer = &ErrorWriter{}
+
+func (e *ErrorWriter) Write([]byte) (int, error) { return 0, e.ReturnError }