archive/tar: expand TestPartialRead to cover sparse files

Given that sparse file logic is not trivial, there should be a test
in TestPartialRead to ensure that partial reads work.

Change-Id: I913da3e331da06dca6758a8be3f5099abba233a6
Reviewed-on: https://go-review.googlesource.com/54430
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/archive/tar/reader_test.go b/src/archive/tar/reader_test.go
index c4fda9d8cddcdc8ba97f88280fdea0b42bf403a6..2e5ff7231752d30785bbbee7509db4ab13903148 100644 (file)
--- a/src/archive/tar/reader_test.go
+++ b/src/archive/tar/reader_test.go
@@ -12,6 +12,7 @@ import (
        "io/ioutil"
        "math"
        "os"
+       "path"
        "reflect"
        "strings"
        "testing"
@@ -431,38 +432,57 @@ func TestReader(t *testing.T) {
 }
 
 func TestPartialRead(t *testing.T) {
-       f, err := os.Open("testdata/gnu.tar")
-       if err != nil {
-               t.Fatalf("Unexpected error: %v", err)
+       type testCase struct {
+               cnt    int    // Number of bytes to read
+               output string // Expected value of string read
        }
-       defer f.Close()
+       vectors := []struct {
+               file  string
+               cases []testCase
+       }{{
+               file: "testdata/gnu.tar",
+               cases: []testCase{
+                       {4, "Kilt"},
+                       {6, "Google"},
+               },
+       }, {
+               file: "testdata/sparse-formats.tar",
+               cases: []testCase{
+                       {2, "\x00G"},
+                       {4, "\x00G\x00o"},
+                       {6, "\x00G\x00o\x00G"},
+                       {8, "\x00G\x00o\x00G\x00o"},
+                       {4, "end\n"},
+               },
+       }}
 
-       tr := NewReader(f)
+       for _, v := range vectors {
+               t.Run(path.Base(v.file), func(t *testing.T) {
+                       f, err := os.Open(v.file)
+                       if err != nil {
+                               t.Fatalf("Open() error: %v", err)
+                       }
+                       defer f.Close()
 
-       // Read the first four bytes; Next() should skip the last byte.
-       hdr, err := tr.Next()
-       if err != nil || hdr == nil {
-               t.Fatalf("Didn't get first file: %v", err)
-       }
-       buf := make([]byte, 4)
-       if _, err := io.ReadFull(tr, buf); err != nil {
-               t.Fatalf("Unexpected error: %v", err)
-       }
-       if expected := []byte("Kilt"); !bytes.Equal(buf, expected) {
-               t.Errorf("Contents = %v, want %v", buf, expected)
-       }
+                       tr := NewReader(f)
+                       for i, tc := range v.cases {
+                               hdr, err := tr.Next()
+                               if err != nil || hdr == nil {
+                                       t.Fatalf("entry %d, Next(): got %v, want %v", i, err, nil)
+                               }
+                               buf := make([]byte, tc.cnt)
+                               if _, err := io.ReadFull(tr, buf); err != nil {
+                                       t.Fatalf("entry %d, ReadFull(): got %v, want %v", i, err, nil)
+                               }
+                               if string(buf) != tc.output {
+                                       t.Fatalf("entry %d, ReadFull(): got %q, want %q", i, string(buf), tc.output)
+                               }
+                       }
 
-       // Second file
-       hdr, err = tr.Next()
-       if err != nil || hdr == nil {
-               t.Fatalf("Didn't get second file: %v", err)
-       }
-       buf = make([]byte, 6)
-       if _, err := io.ReadFull(tr, buf); err != nil {
-               t.Fatalf("Unexpected error: %v", err)
-       }
-       if expected := []byte("Google"); !bytes.Equal(buf, expected) {
-               t.Errorf("Contents = %v, want %v", buf, expected)
+                       if _, err := tr.Next(); err != io.EOF {
+                               t.Fatalf("Next(): got %v, want EOF", err)
+                       }
+               })
        }
 }