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

@@ -11,55 +11,75 @@ 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()
-		deflater.Comment = "comment"
-		deflater.Extra = strings.Bytes("extra")
-		deflater.Mtime = 1e8
-		deflater.Name = "name"
-		_, err = deflater.Write(strings.Bytes("payload"))
-		if err != nil {
-			t.Errorf("%v", err)
-			return
-		}
+		dfunc(deflater)
 	}()
 	inflater, err := NewInflater(piper)
 	if err != nil {
-		t.Errorf("%v", err)
-		return
+		t.Fatalf("%v", err)
 	}
 	defer inflater.Close()
+	ifunc(inflater)
+}
 
-	// Read and compare to the original input.
-	b, err := ioutil.ReadAll(inflater)
-	if err != nil {
-		t.Errorf(": %v", err)
-		return
-	}
-	if string(b) != "payload" {
-		t.Fatalf("payload is %q, want %q", string(b), "payload")
-	}
-	if inflater.Comment != "comment" {
-		t.Fatalf("comment is %q, want %q", inflater.Comment, "comment")
-	}
-	if string(inflater.Extra) != "extra" {
-		t.Fatalf("extra is %q, want %q", inflater.Extra, "extra")
-	}
-	if inflater.Mtime != 1e8 {
-		t.Fatalf("mtime is %d, want %d", inflater.Mtime, uint32(1e8))
-	}
-	if inflater.Name != "name" {
-		t.Fatalf("name is %q, want %q", inflater.Name, "name")
-	}
+// 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"))
+			if err != nil {
+				t.Fatalf("%v", err)
+			}
+		},
+		func(inflater *Inflater) {
+			b, err := ioutil.ReadAll(inflater)
+			if err != nil {
+				t.Fatalf("%v", err)
+			}
+			if string(b) != "payload" {
+				t.Fatalf("payload is %q, want %q", string(b), "payload")
+			}
+			if inflater.Comment != "comment" {
+				t.Fatalf("comment is %q, want %q", inflater.Comment, "comment")
+			}
+			if string(inflater.Extra) != "extra" {
+				t.Fatalf("extra is %q, want %q", inflater.Extra, "extra")
+			}
+			if inflater.Mtime != 1e8 {
+				t.Fatalf("mtime is %d, want %d", inflater.Mtime, uint32(1e8))
+			}
+			if inflater.Name != "name" {
+				t.Fatalf("name is %q, want %q", inflater.Name, "name")
+			}
+		})
 }