Add a GZIP test for the empty payload.

R=rsc, r
CC=golang-dev
https://golang.org/cl/194131

src/pkg/compress/gzip/gzip_test.go

@@ -11,41 +11,60 @@ import (
 	"testing"
 )
 
-// Tests that gzipping and then gunzipping is the identity function.
-func TestWriter(t *testing.T) {
-	// Set up the Pipe to do the gzip and gunzip.
+// pipe creates two ends of a pipe that gzip and gunzip, and runs dfunc at the
+// writer end and ifunc at the reader end.
+func pipe(t *testing.T, dfunc func(*Deflater), ifunc func(*Inflater)) {
 	piper, pipew := io.Pipe()
 	defer piper.Close()
 	go func() {
 		defer pipew.Close()
 		deflater, err := NewDeflater(pipew)
 		if err != nil {
-			t.Errorf("%v", err)
-			return
+			t.Fatalf("%v", err)
 		}
 		defer deflater.Close()
+		dfunc(deflater)
+	}()
+	inflater, err := NewInflater(piper)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+	defer inflater.Close()
+	ifunc(inflater)
+}
+
+// Tests that an empty payload still forms a valid GZIP stream.
+func TestEmpty(t *testing.T) {
+	pipe(t,
+		func(deflater *Deflater) {},
+		func(inflater *Inflater) {
+			b, err := ioutil.ReadAll(inflater)
+			if err != nil {
+				t.Fatalf("%v", err)
+			}
+			if len(b) != 0 {
+				t.Fatalf("did not read an empty slice")
+			}
+		})
+}
+
+// Tests that gzipping and then gunzipping is the identity function.
+func TestWriter(t *testing.T) {
+	pipe(t,
+		func(deflater *Deflater) {
 			deflater.Comment = "comment"
 			deflater.Extra = strings.Bytes("extra")
 			deflater.Mtime = 1e8
 			deflater.Name = "name"
-		_, err = deflater.Write(strings.Bytes("payload"))
+			_, err := deflater.Write(strings.Bytes("payload"))
 			if err != nil {
-			t.Errorf("%v", err)
-			return
+				t.Fatalf("%v", err)
 			}
-	}()
-	inflater, err := NewInflater(piper)
-	if err != nil {
-		t.Errorf("%v", err)
-		return
-	}
-	defer inflater.Close()
-
-	// Read and compare to the original input.
+		},
+		func(inflater *Inflater) {
 			b, err := ioutil.ReadAll(inflater)
 			if err != nil {
-		t.Errorf(": %v", err)
-		return
+				t.Fatalf("%v", err)
 			}
 			if string(b) != "payload" {
 				t.Fatalf("payload is %q, want %q", string(b), "payload")
@@ -62,4 +81,5 @@ func TestWriter(t *testing.T) {
 			if inflater.Name != "name" {
 				t.Fatalf("name is %q, want %q", inflater.Name, "name")
 			}
+		})
 }