Update to allow developers to customize the fetching of the update

information, diffs and binaries

selfupdate/requester.go

@@ -0,0 +1,57 @@
+package selfupdate
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+)
+
+// Requester interface allows developers to customize the method in which
+// requests are made to retrieve the version and binary
+type Requester interface {
+	Fetch(url string) (io.ReadCloser, error)
+}
+
+// HTTPRequester is the normal requester that is used and does an HTTP
+// to the url location requested to retrieve the specified data.
+type HTTPRequester struct {
+}
+
+// Fetch will return an HTTP request to the specified url and return
+// the body of the result. An error will occur for a non 200 status code.
+func (httpRequester *HTTPRequester) Fetch(url string) (io.ReadCloser, error) {
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("bad http status from %s: %v", url, resp.Status)
+	}
+
+	return resp.Body, nil
+}
+
+// mockRequester used for some mock testing to ensure the requester contract
+// works as specified.
+type mockRequester struct {
+	currentIndex int
+	fetches      []func(string) (io.ReadCloser, error)
+}
+
+func (mr *mockRequester) handleRequest(requestHandler func(string) (io.ReadCloser, error)) {
+	if mr.fetches == nil {
+		mr.fetches = []func(string) (io.ReadCloser, error){}
+	}
+	mr.fetches = append(mr.fetches, requestHandler)
+}
+
+func (mr *mockRequester) Fetch(url string) (io.ReadCloser, error) {
+	if len(mr.fetches) <= mr.currentIndex {
+		return nil, fmt.Errorf("No for currentIndex %d to mock", mr.currentIndex)
+	}
+	current := mr.fetches[mr.currentIndex]
+	mr.currentIndex++
+
+	return current(url)
+}

selfupdate/selfupdate.go

@@ -36,15 +36,14 @@ import (
 	"io/ioutil"
 	"log"
 	"math/rand"
-	"net/http"
 	"os"
 	"path/filepath"
 	"runtime"
 	"time"
 
 	"github.com/kardianos/osext"
-	"gopkg.in/inconshreveable/go-update.v0"
 	"github.com/kr/binarydist"
+	"gopkg.in/inconshreveable/go-update.v0"
 )
 
 const (
@@ -56,6 +55,7 @@ const devValidTime = 7 * 24 * time.Hour
 
 var ErrHashMismatch = errors.New("new file hash mismatch after patch")
 var up = update.New()
+var defaultHTTPRequester = HTTPRequester{}
 
 // Updater is the configuration and runtime data for doing an update.
 //
@@ -81,6 +81,7 @@ type Updater struct {
 	BinURL         string    // Base URL for full binary downloads.
 	DiffURL        string    // Base URL for diff downloads.
 	Dir            string    // Directory to store selfupdate state.
+	Requester      Requester //Optional parameter to override existing http request handler
 	Info           struct {
 		Version string
 		Sha256  []byte
@@ -177,7 +178,7 @@ func (u *Updater) update() error {
 }
 
 func (u *Updater) fetchInfo() error {
-	r, err := fetch(u.ApiURL + u.CmdName + "/" + plat + ".json")
+	r, err := u.fetch(u.ApiURL + u.CmdName + "/" + plat + ".json")
 	if err != nil {
 		return err
 	}
@@ -204,7 +205,7 @@ func (u *Updater) fetchAndVerifyPatch(old io.Reader) ([]byte, error) {
 }
 
 func (u *Updater) fetchAndApplyPatch(old io.Reader) ([]byte, error) {
-	r, err := fetch(u.DiffURL + u.CmdName + "/" + u.CurrentVersion + "/" + u.Info.Version + "/" + plat)
+	r, err := u.fetch(u.DiffURL + u.CmdName + "/" + u.CurrentVersion + "/" + u.Info.Version + "/" + plat)
 	if err != nil {
 		return nil, err
 	}
@@ -227,7 +228,7 @@ func (u *Updater) fetchAndVerifyFullBin() ([]byte, error) {
 }
 
 func (u *Updater) fetchBin() ([]byte, error) {
-	r, err := fetch(u.BinURL + u.CmdName + "/" + u.Info.Version + "/" + plat + ".gz")
+	r, err := u.fetch(u.BinURL + u.CmdName + "/" + u.Info.Version + "/" + plat + ".gz")
 	if err != nil {
 		return nil, err
 	}
@@ -249,15 +250,21 @@ func randDuration(n time.Duration) time.Duration {
 	return time.Duration(rand.Int63n(int64(n)))
 }
 
-func fetch(url string) (io.ReadCloser, error) {
-	resp, err := http.Get(url)
+func (u *Updater) fetch(url string) (io.ReadCloser, error) {
+	if u.Requester == nil {
+		return defaultHTTPRequester.Fetch(url)
+	}
+
+	readCloser, err := u.Requester.Fetch(url)
 	if err != nil {
 		return nil, err
 	}
-	if resp.StatusCode != 200 {
-		return nil, fmt.Errorf("bad http status from %s: %v", url, resp.Status)
+
+	if readCloser == nil {
+		return nil, fmt.Errorf("Fetch was expected to return non-nil ReadCloser")
 	}
-	return resp.Body, nil
+
+	return readCloser, nil
 }
 
 func readTime(path string) time.Time {

selfupdate/selfupdate_test.go

@@ -1,6 +1,79 @@
 package selfupdate
 
-import "testing"
+import (
+	"bytes"
+	"crypto/sha256"
+	"fmt"
+	"io"
+	"testing"
+)
 
-func TestUpdater(t *testing.T) {
+var testHash = sha256.New()
+
+func TestUpdaterFetchMustReturnNonNilReaderCloser(t *testing.T) {
+	mr := &mockRequester{}
+	mr.handleRequest(
+		func(url string) (io.ReadCloser, error) {
+			return nil, nil
+		})
+	updater := createUpdater(mr)
+	err := updater.BackgroundRun()
+	if err != nil {
+		equals(t, "Fetch was expected to return non-nil ReadCloser", err.Error())
+	} else {
+		t.Log("Expected an error")
+		t.Fail()
+	}
+
+}
+
+func TestUpdaterWithEmptyPaloadNoErrorNoUpdate(t *testing.T) {
+	mr := &mockRequester{}
+	mr.handleRequest(
+		func(url string) (io.ReadCloser, error) {
+			equals(t, "http://updates.yourdomain.com/myapp/darwin-amd64.json", url)
+			return newTestReaderCloser("{}"), nil
+		})
+	updater := createUpdater(mr)
+
+	err := updater.BackgroundRun()
+	if err != nil {
+		t.Errorf("Error occured: %#v", err)
+	}
+
+}
+
+func createUpdater(mr *mockRequester) *Updater {
+	return &Updater{
+		CurrentVersion: "1.2",
+		ApiURL:         "http://updates.yourdomain.com/",
+		BinURL:         "http://updates.yourdownmain.com/",
+		DiffURL:        "http://updates.yourdomain.com/",
+		Dir:            "update/",
+		CmdName:        "myapp", // app name
+		Requester:      mr,
+	}
+}
+
+func equals(t *testing.T, expected, actual interface{}) {
+	if expected != actual {
+		t.Log(fmt.Sprintf("Expected: %#v %#v\n", expected, actual))
+		t.Fail()
+	}
+}
+
+type testReadCloser struct {
+	buffer *bytes.Buffer
+}
+
+func newTestReaderCloser(payload string) io.ReadCloser {
+	return &testReadCloser{buffer: bytes.NewBufferString(payload)}
+}
+
+func (trc *testReadCloser) Read(p []byte) (n int, err error) {
+	return trc.buffer.Read(p)
+}
+
+func (trc *testReadCloser) Close() error {
+	return nil
 }