SQUASH: Address feedback

* Change to use `assert.Contains`.
* Test Warning message.

Signed-off-by: Marcus Martins <marcus@docker.com>

cli/command/registry_test.go

@@ -5,13 +5,13 @@ import (
 	"testing"
 
 	"github.com/pkg/errors"
+	"github.com/stretchr/testify/assert"
 	"golang.org/x/net/context"
 
 	. "github.com/docker/cli/cli/command"
 	"github.com/docker/cli/cli/internal/test"
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/client"
-	"github.com/stretchr/testify/require"
 )
 
 type fakeClient struct {
@@ -29,28 +29,33 @@ func (cli *fakeClient) Info(_ context.Context) (types.Info, error) {
 func TestElectAuthServer(t *testing.T) {
 	testCases := []struct {
 		expectedAuthServer string
+		expectedWarning    string
 		infoFunc           func() (types.Info, error)
 	}{
 		{
 			expectedAuthServer: "https://index.docker.io/v1/",
+			expectedWarning:    "",
 			infoFunc: func() (types.Info, error) {
 				return types.Info{IndexServerAddress: "https://index.docker.io/v1/"}, nil
 			},
 		},
 		{
 			expectedAuthServer: "https://index.docker.io/v1/",
+			expectedWarning:    "Empty registry endpoint from daemon",
 			infoFunc: func() (types.Info, error) {
 				return types.Info{IndexServerAddress: ""}, nil
 			},
 		},
 		{
 			expectedAuthServer: "https://foo.bar",
+			expectedWarning:    "",
 			infoFunc: func() (types.Info, error) {
 				return types.Info{IndexServerAddress: "https://foo.bar"}, nil
 			},
 		},
 		{
 			expectedAuthServer: "https://index.docker.io/v1/",
+			expectedWarning:    "failed to get default registry endpoint from daemon",
 			infoFunc: func() (types.Info, error) {
 				return types.Info{}, errors.Errorf("error getting info")
 			},
@@ -59,7 +64,16 @@ func TestElectAuthServer(t *testing.T) {
 	for _, tc := range testCases {
 		buf := new(bytes.Buffer)
 		cli := test.NewFakeCli(&fakeClient{infoFunc: tc.infoFunc}, buf)
+		outBuf := new(bytes.Buffer)
+		cli.SetOut(outBuf)
 		server := ElectAuthServer(context.Background(), cli)
-		require.Equal(t, tc.expectedAuthServer, server)
+		assert.Equal(t, tc.expectedAuthServer, server)
+		actual := outBuf.String()
+		if tc.expectedWarning == "" {
+			assert.Empty(t, actual)
+		} else {
+			assert.Contains(t, actual, tc.expectedWarning)
+		}
+
 	}
 }

cli/internal/test/cli.go

@@ -42,6 +42,11 @@ func (c *FakeCli) SetErr(err io.Writer) {
 	c.err = err
 }
 
+// SetOut sets the stderr stream for the cli to the specified io.Writer
+func (c *FakeCli) SetOut(out io.Writer) {
+	c.out = command.NewOutStream(out)
+}
+
 // SetConfigfile sets the "fake" config file
 func (c *FakeCli) SetConfigfile(configfile *configfile.ConfigFile) {
 	c.configfile = configfile