fix: allow required flag with one character (#1449)

* fix: allow required flag with one character

* fix: update test case

Author: Gerrard-YNWA

context.go

@@ -170,9 +170,7 @@ func (cCtx *Context) checkRequiredFlags(flags []Flag) requiredFlagsErr {
 			var flagName string
 
 			for _, key := range f.Names() {
-				if len(key) > 1 {
-					flagName = key
-				}
+				flagName = key
 
 				if cCtx.IsSet(strings.TrimSpace(key)) {
 					flagPresent = true

context_test.go

@@ -556,6 +556,14 @@ func TestCheckRequiredFlags(t *testing.T) {
 				&StringSliceFlag{Name: "names, n", Required: true},
 			},
 		},
+		{
+			testCase:              "required_flag_with_one_character",
+			expectedAnError:       true,
+			expectedErrorContents: []string{"Required flag \"n\" not set"},
+			flags: []Flag{
+				&StringFlag{Name: "n", Required: true},
+			},
+		},
 	}
 
 	for _, test := range tdata {