Retain entered flag spellings in parser failures

internal/cobra/flags_test.go

@@ -2,6 +2,7 @@ package cobra
 
 import (
 	"reflect"
+	"strings"
 	"testing"
 
 	commandmeta "gitea.maximumdirect.net/eric/CommandKit/internal/commandmeta"
@@ -158,3 +159,40 @@ func TestParseFlagAliasOccurrenceOrderAndSpellings(t *testing.T) {
 		t.Fatalf("tag spellings = %#v, want %#v", got, want)
 	}
 }
+
+func TestParseFailuresRetainEnteredFlagSpellings(t *testing.T) {
+	for _, spelling := range []string{"--color", "--colour", "-c", "-C"} {
+		t.Run("missing/"+spelling, func(t *testing.T) {
+			result := Parse(flagGrammarTree(), []string{"run", spelling}, flagGrammarOptions())
+			if result.Failure == nil || !strings.Contains(result.Failure.Message, ": "+spelling) {
+				t.Fatalf("missing value failure = %#v, want entered spelling %q", result.Failure, spelling)
+			}
+		})
+	}
+	result := Parse(flagGrammarTree(), []string{"run", "-wC"}, flagGrammarOptions())
+	if result.Failure == nil || !strings.Contains(result.Failure.Message, ": -C") {
+		t.Fatalf("cluster missing value failure = %#v", result.Failure)
+	}
+	for _, test := range []struct {
+		args     []string
+		spelling string
+	}{
+		{[]string{"--hlep=bad"}, "--hlep"},
+		{[]string{"-h=bad"}, "-h"},
+		{[]string{"--help=bad"}, "--help"},
+		{[]string{"--hlep=bad", "--help=true"}, "--hlep"},
+		{[]string{"-h=bad", "--hlep=true"}, "-h"},
+		{[]string{"--help=true", "--hlep=bad"}, "--hlep"},
+	} {
+		t.Run(strings.Join(test.args, " "), func(t *testing.T) {
+			result := Parse(flagGrammarTree(), append([]string{"run"}, test.args...), flagGrammarOptions())
+			if result.Failure == nil || !strings.Contains(result.Failure.Message, "for "+test.spelling) {
+				t.Fatalf("help failure = %#v, want entered spelling %q", result.Failure, test.spelling)
+			}
+		})
+	}
+	result = Parse(flagGrammarTree(), []string{"run", "--unknown", "--colour"}, flagGrammarOptions())
+	if result.Failure == nil || !strings.Contains(result.Failure.Message, "unknown") || strings.Contains(result.Failure.Message, "needs an argument") {
+		t.Fatalf("earlier parser failure = %#v", result.Failure)
+	}
+}