make error channel empty by default

clone.go

@@ -29,7 +29,6 @@ func newCloner(dest string, extract *regexp.Regexp) *cloner {
 		dest:    dest,
 		extract: extract,
 		repos:   make(chan string, maxBuffer),
-		err:     make(chan error),
 	}
 
 	if c.git == "" {
@@ -71,7 +70,9 @@ func (cl *cloner) newWorker() {
 
 			if err != nil {
 				log.Println("Failed to clone", repo, err)
-				cl.err <- err
+				if cl.err != nil {
+					cl.err <- err
+				}
 				continue
 			}
 
@@ -91,7 +92,9 @@ func (cl *cloner) newWorker() {
 					return nil
 				}); err != nil {
 					log.Println("Failed to extract files", repo, extract.String(), err)
-					cl.err <- err
+					if cl.err != nil {
+						cl.err <- err
+					}
 					return
 				}
 			}
@@ -110,5 +113,7 @@ func (cl *cloner) start() {
 func (cl *cloner) shutdown() {
 	close(cl.repos)
 	cl.wg.Wait()
-	close(cl.err)
+	if cl.err != nil {
+		close(cl.err)
+	}
 }

clone_test.go

@@ -30,6 +30,7 @@ func testRepos(repos []string, t *testing.T) {
 	defer func() {
 		os.RemoveAll("test")
 	}()
+	c.err = make(chan error, 10)
 	c.start()
 
 	go func() {
@@ -90,6 +91,7 @@ func TestCloneWithExtract(t *testing.T) {
 	defer func() {
 		os.RemoveAll("test")
 	}()
+	c.err = make(chan error, 10)
 	c.start()
 
 	go func() {
@@ -117,7 +119,7 @@ func TestCloneWithExtract(t *testing.T) {
 func TestCloneNotExistingRepo(t *testing.T) {
 	c := newCloner("test", nil)
 	c.ssh = true
-	c.err = make(chan error, 10) // Buffer errors to make test easier
+	c.err = make(chan error, 10)
 	c.start()
 
 	c.clone("rhysd/not-existing-repository")

collect.go

@@ -39,14 +39,8 @@ func (col *collector) searchRepos() (*github.RepositoriesSearchResult, error) {
 func (col *collector) collect() (int, int, error) {
 	log.Println("Searching GitHub repositories with query:", col.query)
 	cloner := newCloner(col.dest, col.extract)
-	go func() {
-		for range cloner.err {
-			// Do nothing because error is already reported in cloner
-			// Error is reported in cloner because cloner can show more descriptive error message
-		}
-	}()
-
 	cloner.start()
+
 	total := 0
 	count := 0
 	for col.page <= col.maxPage {