want: []string{"foo", "bar"},
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if err := yaml.Unmarshal([]byte(tt.args.yamlStr), &tt.b); (err != nil) != tt.wantErr {
				t.Errorf("UnmarshalYAML() error = %v, wantErr %v", err, tt.wantErr)
			}
			if !slices.Equal(tt.b.Prefix.F(), tt.want) {
				t.Errorf("UnmarshalYAML() = %v, want %v", tt.b.Prefix.F(), tt.want)
			}
		})
	}

		// We should get a no exit code error
		if err == nil || !wantErr.MatchString(err.Error()) {
			t.Errorf("want error matching %s, got %s", wantErr, err)
		}
		// And it should flush all output (even if it looks
		// like we may be getting an exit code)
		if got := out.String(); text != got {
			t.Errorf("want full output %q, got %q", text, got)
		}
	}
	wantErr = regexp.MustCompile("^no exit code")
	check("abc")
	check("exitcode")

	}
	for _, tt := range tests {
		got, err := parseHexUint([]byte(tt.in))
		if tt.wantErr != "" {
			if err != nil && !strings.Contains(err.Error(), tt.wantErr) {
				t.Errorf("parseHexUint(%q) = %v, %v; want error %q", tt.in, got, err, tt.wantErr)
			}
		} else {
			if err != nil || got != tt.want {
				t.Errorf("parseHexUint(%q) = %v, %v; want %v", tt.in, got, err, tt.want)
			}

		rn, err := r.ReadAt(b, tt.off)
		got := string(b[:rn])
		if got != tt.want {
			t.Errorf("%d. got %q; want %q", i, got, tt.want)
		}
		if fmt.Sprintf("%v", err) != fmt.Sprintf("%v", tt.wanterr) {
			t.Errorf("%d. got error = %v; want %v", i, err, tt.wanterr)
		}
	}
}

func TestReaderAtConcurrent(t *testing.T) {
	// Test for the race detector, to verify ReadAt doesn't mutate
	// any state.
	r := NewReader([]byte("0123456789"))