all: avoid leaking fds during tests

trivial: it is not a serious problem to leak a fd in a short lived process, but it was obscuring my investigation of issue 5593.

R=golang-dev, iant, bradfitz
CC=golang-dev
https://golang.org/cl/10391043

src/pkg/archive/tar/reader_test.go

@@ -171,6 +171,7 @@ testLoop:
 			t.Errorf("test %d: Unexpected error: %v", i, err)
 			continue
 		}
+		defer f.Close()
 		tr := NewReader(f)
 		for j, header := range test.headers {
 			hdr, err := tr.Next()
@@ -191,7 +192,6 @@ testLoop:
 		if hdr != nil || err != nil {
 			t.Errorf("test %d: Unexpected entry or error: hdr=%v err=%v", i, hdr, err)
 		}
-		f.Close()
 	}
 }
 

src/pkg/archive/zip/reader_test.go

@@ -276,6 +276,7 @@ func readTestZip(t *testing.T, zt ZipTest) {
 		var rc *ReadCloser
 		rc, err = OpenReader(filepath.Join("testdata", zt.Name))
 		if err == nil {
+			defer rc.Close()
 			z = &rc.Reader
 		}
 	}

src/pkg/debug/elf/file_test.go

@@ -166,6 +166,7 @@ func TestOpen(t *testing.T) {
 		} else {
 			f, err = Open(tt.file)
 		}
+		defer f.Close()
 		if err != nil {
 			t.Errorf("cannot open file %s: %v", tt.file, err)
 			continue

src/pkg/log/syslog/syslog_test.go

@@ -255,6 +255,7 @@ func TestWrite(t *testing.T) {
 			if err != nil {
 				t.Fatalf("syslog.Dial() failed: %v", err)
 			}
+			defer l.Close()
 			_, err = io.WriteString(l, test.msg)
 			if err != nil {
 				t.Fatalf("WriteString() failed: %v", err)
@@ -328,6 +329,7 @@ func TestConcurrentReconnect(t *testing.T) {
 			if err != nil {
 				t.Fatalf("syslog.Dial() failed: %v", err)
 			}
+			defer w.Close()
 			for i := 0; i < M; i++ {
 				err := w.Info("test")
 				if err != nil {

src/pkg/net/net_test.go

@@ -25,6 +25,7 @@ func TestShutdown(t *testing.T) {
 	}
 
 	go func() {
+		defer ln.Close()
 		c, err := ln.Accept()
 		if err != nil {
 			t.Fatalf("Accept: %v", err)
@@ -75,7 +76,10 @@ func TestShutdownUnix(t *testing.T) {
 	if err != nil {
 		t.Fatalf("ListenUnix on %s: %s", tmpname, err)
 	}
-	defer os.Remove(tmpname)
+	defer func() {
+		ln.Close()
+		os.Remove(tmpname)
+	}()
 
 	go func() {
 		c, err := ln.Accept()

src/pkg/net/parse_test.go

@@ -23,12 +23,14 @@ func TestReadLine(t *testing.T) {
 	if err != nil {
 		t.Fatalf("open %s: %v", filename, err)
 	}
+	defer fd.Close()
 	br := bufio.NewReader(fd)
 
 	file, err := open(filename)
 	if file == nil {
 		t.Fatalf("net.open(%s) = nil", filename)
 	}
+	defer file.close()
 
 	lineno := 1
 	byteno := 0

src/pkg/os/os_test.go

@@ -299,6 +299,7 @@ func TestReaddirnamesOneAtATime(t *testing.T) {
 	if err2 != nil {
 		t.Fatalf("open %q failed: %v", dir, err2)
 	}
+	defer file1.Close()
 	small := smallReaddirnames(file1, len(all)+100, t) // +100 in case we screw up
 	if len(small) < len(all) {
 		t.Fatalf("len(small) is %d, less than %d", len(small), len(all))
@@ -526,6 +527,7 @@ func exec(t *testing.T, dir, cmd string, args []string, expect string) {
 	if err != nil {
 		t.Fatalf("Pipe: %v", err)
 	}
+	defer r.Close()
 	attr := &ProcAttr{Dir: dir, Files: []*File{nil, w, Stderr}}
 	p, err := StartProcess(cmd, args, attr)
 	if err != nil {
@@ -844,6 +846,7 @@ func run(t *testing.T, cmd []string) string {
 	if err != nil {
 		t.Fatal(err)
 	}
+	defer r.Close()
 	p, err := StartProcess("/bin/hostname", []string{"hostname"}, &ProcAttr{Files: []*File{nil, w, Stderr}})
 	if err != nil {
 		t.Fatal(err)