linting: os.Setenv() can be replaced by `t.Setenv()` (tenv)

cli/command/cli_options_test.go:29:2: os.Setenv() can be replaced by `t.Setenv()` in TestWithContentTrustFromEnv (tenv)
        os.Setenv(envvar, "true")
        ^
    cli/command/cli_options_test.go:31:2: os.Setenv() can be replaced by `t.Setenv()` in TestWithContentTrustFromEnv (tenv)
        os.Setenv(envvar, "false")
        ^
    cli/command/cli_options_test.go:33:2: os.Setenv() can be replaced by `t.Setenv()` in TestWithContentTrustFromEnv (tenv)
        os.Setenv(envvar, "invalid")
        ^

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

cli/command/cli_options_test.go

@@ -15,23 +15,13 @@ func contentTrustEnabled(t *testing.T) bool {
 
 // NB: Do not t.Parallel() this test -- it messes with the process environment.
 func TestWithContentTrustFromEnv(t *testing.T) {
-	envvar := "DOCKER_CONTENT_TRUST"
+	const envvar = "DOCKER_CONTENT_TRUST"
-	if orig, ok := os.LookupEnv(envvar); ok {
+	t.Setenv(envvar, "true")
-		defer func() {
+	assert.Check(t, contentTrustEnabled(t))
-			os.Setenv(envvar, orig)
+	t.Setenv(envvar, "false")
-		}()
+	assert.Check(t, !contentTrustEnabled(t))
-	} else {
+	t.Setenv(envvar, "invalid")
-		defer func() {
+	assert.Check(t, contentTrustEnabled(t))
 	os.Unsetenv(envvar)
-		}()
+	assert.Check(t, !contentTrustEnabled(t))
-	}
-
-	os.Setenv(envvar, "true")
-	assert.Assert(t, contentTrustEnabled(t))
-	os.Setenv(envvar, "false")
-	assert.Assert(t, !contentTrustEnabled(t))
-	os.Setenv(envvar, "invalid")
-	assert.Assert(t, contentTrustEnabled(t))
-	os.Unsetenv(envvar)
-	assert.Assert(t, !contentTrustEnabled(t))
 }