tr := NewReader(&buffer)

	for {
		header, err := tr.Next()
		if err == io.EOF {
			break
		}
		if err != nil {
			t.Fatalf("Failed to read header: %s", err)
		}
		if header.Typeflag != TypeReg {
			t.Fatalf("Typeflag should've been %d, found %d", TypeReg, header.Typeflag)
		}
	}
}

// failOnceWriter fails exactly once and then always reports success.
type failOnceWriter bool

			}
			checkOutput(t, w.String(), tt.expected, tt.unexpected)
		})
	}
}

func checkOutput(t *testing.T, output string, expected, unexpected []string) {
	t.Helper()
	for _, expected := range expected {
		if !strings.Contains(output, expected) {
			t.Errorf("expected %s included in writer output, did not find", expected)
		}
	}
	for _, unexpected := range unexpected {

		}
	}
}

func testCreate(t *testing.T, w *Writer, wt *WriteTest) {
	header := &FileHeader{
		Name:   wt.Name,
		Method: wt.Method,
	}
	if wt.Mode != 0 {
		header.SetMode(wt.Mode)
	}
	f, err := w.CreateHeader(header)
	if err != nil {
		t.Fatal(err)
	}
	_, err = f.Write(wt.Data)
	if err != nil {
		t.Fatal(err)
	}
}