force TestNewHistoryCommandSuccess to use UTC timezone

This test was skipped if the host was not using UTC timezone, because the output
of timestamps would be different, causing the test to fail.

This patch overrides the TZ env-var to make the test use UTC, so that we don't
have to skip the test.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/image/history_test.go

@@ -11,7 +11,6 @@ import (
 	"github.com/pkg/errors"
 	"gotest.tools/v3/assert"
 	"gotest.tools/v3/golden"
-	"gotest.tools/v3/skip"
 )
 
 func TestNewHistoryCommandErrors(t *testing.T) {
@@ -43,16 +42,7 @@ func TestNewHistoryCommandErrors(t *testing.T) {
 	}
 }
 
-func notUTCTimezone() bool {
-	if _, offset := time.Now().Zone(); offset != 0 {
-		return true
-	}
-	return false
-}
-
 func TestNewHistoryCommandSuccess(t *testing.T) {
-	skip.If(t, notUTCTimezone, "expected output requires UTC timezone")
-
 	testCases := []struct {
 		name             string
 		args             []string
@@ -65,6 +55,7 @@ func TestNewHistoryCommandSuccess(t *testing.T) {
 				return []image.HistoryResponseItem{{
 					ID:      "1234567890123456789",
 					Created: time.Now().Unix(),
+					Comment: "none",
 				}}, nil
 			},
 		},
@@ -98,6 +89,9 @@ func TestNewHistoryCommandSuccess(t *testing.T) {
 	for _, tc := range testCases {
 		tc := tc
 		t.Run(tc.name, func(t *testing.T) {
+			// Set to UTC timezone as timestamps in output are
+			// printed in the current timezone
+			t.Setenv("TZ", "UTC")
 			cli := test.NewFakeCli(&fakeClient{imageHistoryFunc: tc.imageHistoryFunc})
 			cmd := NewHistoryCommand(cli)
 			cmd.SetOut(io.Discard)

cli/command/image/testdata/history-command-success.simple.golden

@@ -1,2 +1,2 @@
 IMAGE          CREATED                  CREATED BY   SIZE      COMMENT
-123456789012   Less than a second ago                0B        
+123456789012   Less than a second ago                0B        none