}
			f.Close()
		}

		bs, err := os.ReadFile(goldenFile)
		if err != nil {
			t.Fatalf("opening golden.txt for package %q: %v", fi.Name(), err)
		}
		wanted := strings.Split(string(bs), "\n")
		sort.Strings(wanted)
		for _, feature := range wanted {
			if feature == "" {
				continue
			}
			_, ok := w.features[feature]
			if !ok {
				t.Errorf("package %s: missing feature %q", fi.Name(), feature)
			}

			continue
		}
		// Two flushes, to verify the error is sticky.
		for i := 0; i < 2; i++ {
			e = buf.Flush()
			if e != w.expect {
				t.Errorf("Flush %d/2 %v: got %v, wanted %v", i+1, w, e, w.expect)
			}
		}
	}
}

func TestNewReaderSizeIdempotent(t *testing.T) {
	const BufSize = 1000
	b := NewReaderSize(strings.NewReader("hello world"), BufSize)

	KANDD K5, K5, K5                                   // c4e1d541ed
	KANDND K5, K0, K4                                  // c4e1fd42e5
	KANDND K4, K0, K4                                  // c4e1fd42e4
	KANDND K5, K7, K4                                  // c4e1c542e5
	KANDND K4, K7, K4                                  // c4e1c542e4
	KANDND K5, K0, K6                                  // c4e1fd42f5

		if wantFormat.has(FormatPAX) && !preferPAX {
			wantFormat.mayBe(FormatUSTAR) // PAX implies USTAR allowed too
		}
		format.mayOnlyBe(wantFormat) // Set union of formats allowed and format wanted
	}
	if format == FormatUnknown {
		switch h.Format {
		case FormatUSTAR:
			err = headerError{"Format specifies USTAR", whyNoUSTAR, whyOnlyPAX, whyOnlyGNU}
		case FormatPAX:

	if err != nil {
		t.Fatalf("Unexpected error: %v", err)
	}
	defer f.Close()

	tr := NewReader(f)
	_, err = tr.Read([]byte{})
	if err == nil || err != io.EOF {
		t.Errorf("Unexpected error: %v, wanted %v", err, io.EOF)
	}

}

type reader struct{ io.Reader }
type readSeeker struct{ io.ReadSeeker }
type readBadSeeker struct{ io.ReadSeeker }