Backported from upstream PR: https://github.com/urfave/cli/pull/1299
---
diff --git a/app_test.go b/app_test.go
index 33024ff..6b3aaa3 100644
--- a/app_test.go
+++ b/app_test.go
@@ -513,18 +513,18 @@ func TestApp_RunAsSubcommandParseFlags(t *testing.T) {
 func TestApp_RunAsSubCommandIncorrectUsage(t *testing.T) {
 	a := App{
 		Flags: []Flag{
-			StringFlag{Name: "--foo"},
+			StringFlag{Name: "foo"},
 		},
 		Writer: bytes.NewBufferString(""),
 	}
 
 	set := flag.NewFlagSet("", flag.ContinueOnError)
-	_ = set.Parse([]string{"", "---foo"})
+	_ = set.Parse([]string{"", "-bar"})
 	c := &Context{flagSet: set}
 
 	err := a.RunAsSubcommand(c)
 
-	expect(t, err, errors.New("bad flag syntax: ---foo"))
+	expect(t, err.Error(), "flag provided but not defined: -bar")
 }
 
 func TestApp_CommandWithFlagBeforeTerminator(t *testing.T) {
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<tr><td><span title='2019-02-18 01:52:47 +0100'>2019-02-18</span></td><td><a href='/guix/commit/gnu/installer/timezone.scm?id=b83e4a93a2118513cdd2186d796729f0813264c0'>gnu: Fix some typos in the installer.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2019-01-17 14:04:22 +0100'>2019-01-17</span></td><td><a href='/guix/commit/gnu/installer/timezone.scm?id=dc5f3275ecbddc804875899e9e457299a835d7ab'>installer: Add configuration formatter.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2019-01-17 14:04:20 +0100'>2019-01-17</span></td><td><a href='/guix/commit/gnu/installer/timezone.scm?id=d0f3a672dcbdfefd3556b6a21985ff0e35eed3be'>gnu: Add graphical installer support.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>