Tests for DownloadTryCompression + error return bugfix.

utils/download.go

@@ -164,12 +164,15 @@ func DownloadTryCompression(downloader Downloader, url string) (io.Reader, *os.F
 	var err error
 
 	for _, method := range compressionMethods {
-		file, err := DownloadTemp(downloader, url+method.extenstion)
+		var file *os.File
+
+		file, err = DownloadTemp(downloader, url+method.extenstion)
 		if err != nil {
 			continue
 		}
 
-		uncompressed, err := method.transformation(file)
+		var uncompressed io.Reader
+		uncompressed, err = method.transformation(file)
 		if err != nil {
 			continue
 		}

utils/download_test.go

@@ -1,6 +1,8 @@
 package utils
 
 import (
+	"errors"
+	"io"
 	"io/ioutil"
 	. "launchpad.net/gocheck"
 	"os"
@@ -101,3 +103,75 @@ func (s *DownloaderSuite) TestDownloadTempError(c *C) {
 	c.Assert(f, IsNil)
 	c.Assert(err, ErrorMatches, "HTTP code 404.*")
 }
+
+const (
+	bzipData = "BZh91AY&SY\xcc\xc3q\xd4\x00\x00\x02A\x80\x00\x10\x02\x00\x0c\x00 \x00!\x9ah3M\x19\x97\x8b\xb9\"\x9c(Hfa\xb8\xea\x00"
+	gzipData = "\x1f\x8b\x08\x00\xc8j\xb0R\x00\x03+I-.\xe1\x02\x00\xc65\xb9;\x05\x00\x00\x00"
+	rawData  = "test"
+)
+
+func (s *DownloaderSuite) TestDownloadTryCompression(c *C) {
+	var buf []byte
+
+	// bzip2 only available
+	buf = make([]byte, 4)
+	d := NewFakeDownloader()
+	d.ExpectResponse("http://example.com/file.bz2", bzipData)
+	r, file, err := DownloadTryCompression(d, "http://example.com/file")
+	c.Assert(err, IsNil)
+	defer file.Close()
+	io.ReadFull(r, buf)
+	c.Assert(string(buf), Equals, rawData)
+	c.Assert(d.Empty(), Equals, true)
+
+	// bzip2 not available, but gz is
+	buf = make([]byte, 4)
+	d = NewFakeDownloader()
+	d.ExpectError("http://example.com/file.bz2", errors.New("404"))
+	d.ExpectResponse("http://example.com/file.gz", gzipData)
+	r, file, err = DownloadTryCompression(d, "http://example.com/file")
+	c.Assert(err, IsNil)
+	defer file.Close()
+	io.ReadFull(r, buf)
+	c.Assert(string(buf), Equals, rawData)
+	c.Assert(d.Empty(), Equals, true)
+
+	// bzip2 & gzip not available, but raw is
+	buf = make([]byte, 4)
+	d = NewFakeDownloader()
+	d.ExpectError("http://example.com/file.bz2", errors.New("404"))
+	d.ExpectError("http://example.com/file.gz", errors.New("404"))
+	d.ExpectResponse("http://example.com/file", rawData)
+	r, file, err = DownloadTryCompression(d, "http://example.com/file")
+	c.Assert(err, IsNil)
+	defer file.Close()
+	io.ReadFull(r, buf)
+	c.Assert(string(buf), Equals, rawData)
+	c.Assert(d.Empty(), Equals, true)
+
+	// gzip available, but broken
+	buf = make([]byte, 4)
+	d = NewFakeDownloader()
+	d.ExpectError("http://example.com/file.bz2", errors.New("404"))
+	d.ExpectResponse("http://example.com/file.gz", "x")
+	d.ExpectResponse("http://example.com/file", "recovered")
+	r, file, err = DownloadTryCompression(d, "http://example.com/file")
+	c.Assert(err, IsNil)
+	defer file.Close()
+	io.ReadFull(r, buf)
+	c.Assert(string(buf), Equals, "reco")
+	c.Assert(d.Empty(), Equals, true)
+}
+
+func (s *DownloaderSuite) TestDownloadTryCompressionErrors(c *C) {
+	d := NewFakeDownloader()
+	_, _, err := DownloadTryCompression(d, "http://example.com/file")
+	c.Assert(err, ErrorMatches, "unexpected request.*")
+
+	d = NewFakeDownloader()
+	d.ExpectError("http://example.com/file.bz2", errors.New("404"))
+	d.ExpectError("http://example.com/file.gz", errors.New("404"))
+	d.ExpectError("http://example.com/file", errors.New("403"))
+	_, _, err = DownloadTryCompression(d, "http://example.com/file")
+	c.Assert(err, ErrorMatches, "403")
+}