Improve Code and Add Test Case

context.go

@@ -314,14 +314,16 @@ func checkRequiredFlags(flags []Flag, context *Context) requiredFlagsErr {
 	for _, f := range flags {
 		if rf, ok := f.(RequiredFlag); ok && rf.IsRequired() {
 			key := strings.Split(f.GetName(), ",")
+			shortName := strings.TrimSpace(key[0])
 			if len(key) > 1 {
 				// has short name
-				if !context.IsSet(strings.TrimSpace(key[0])) && !context.IsSet(strings.TrimSpace(key[1])) {
+				longName := strings.TrimSpace(key[1])
+				if !context.IsSet(shortName) && !context.IsSet(longName) {
 					missingFlags = append(missingFlags, key[0])
 				}
 			} else {
 				// does not have short name
-				if !context.IsSet(strings.TrimSpace(key[0])) {
+				if !context.IsSet(shortName) {
 					missingFlags = append(missingFlags, key[0])
 				}
 			}

context_test.go

@@ -517,6 +517,13 @@ func TestCheckRequiredFlags(t *testing.T) {
 			},
 			parseInput: []string{"--requiredFlag", "myinput", "--requiredFlagTwo", "myinput"},
 		},
+		{
+			testCase: "required_flag_with_short_name",
+			flags: []Flag{
+				StringSliceFlag{Name: "names, N", Required: true},
+			},
+			parseInput: []string{"-N", "asd", "-N", "qwe"},
+		},
 	}
 	for _, test := range tdata {
 		t.Run(test.testCase, func(t *testing.T) {