Inject io.Writer for fmt to write to. So much easier to handle in tests

Author: KenjiTakahashi

ctlcmds.go

@@ -21,10 +21,7 @@
 
 package main
 
-import (
-	"fmt"
-	"strings"
-)
+import "strings"
 
 // ctlCmd Defines methods common for svctl meta-commands, i.e. ones
 // that are not sent to runit, but executed locally.
@@ -91,9 +88,9 @@ func (c *ctlCmdHelp) Run(ctl *ctl, params []string) bool {
 	for _, param := range params[1:] {
 		cmd := cmdMatch(param)
 		if cmd == nil {
-			fmt.Printf("%s: unable to find action\n", param)
+			ctl.printf("%s: unable to find action\n", param)
 		} else {
-			fmt.Println(cmd.Help())
+			ctl.println(cmd.Help())
 		}
 	}
 	return false

svctl.go

@@ -146,12 +146,13 @@ func (s *status) Errored() bool {
 type ctl struct {
 	line    *liner.State
 	basedir string
+	stdout  io.Writer
 }
 
 // newCtl Creates new ctl instance.
 // Initializes input prompt, reads history, reads $SVDIR.
-func newCtl() *ctl {
-	c := &ctl{line: liner.NewLiner()}
+func newCtl(stdout io.Writer) *ctl {
+	c := &ctl{line: liner.NewLiner(), stdout: stdout}
 
 	fn, _ := xdg.DataFile("svctl/hist")
 	if f, err := os.Open(fn); err == nil {
@@ -207,6 +208,14 @@ func (c *ctl) completer(line string, pos int) (h string, compl []string, t strin
 	return
 }
 
+func (c *ctl) printf(format string, a ...interface{}) {
+	fmt.Fprintf(c.stdout, format, a...)
+}
+
+func (c *ctl) println(a ...interface{}) {
+	fmt.Fprintln(c.stdout, a...)
+}
+
 // serviceName Returns name of the service, i.e. directory chain relative to current base.
 func (c *ctl) serviceName(dir string) string {
 	if name, err := filepath.Rel(c.basedir, dir); err == nil {
@@ -256,7 +265,7 @@ func (c *ctl) Status(id string, toLog bool) {
 	}
 	for _, status := range statuses {
 		status.Offsets = statuses[0].Offsets
-		fmt.Println(status)
+		c.println(status)
 	}
 }
 
@@ -281,12 +290,12 @@ func (c *ctl) ctl(action []byte, service string, start uint64, wg *sync.WaitGrou
 
 	status := newStatus(service, c.serviceName(service))
 	if status.Errored() {
-		fmt.Println(status)
+		c.println(status)
 		return
 	}
 	if status.CheckControl(action) {
 		if err := c.control(action, service); err != nil {
-			fmt.Println(err)
+			c.println(err)
 			return
 		}
 	}
@@ -296,13 +305,13 @@ func (c *ctl) ctl(action []byte, service string, start uint64, wg *sync.WaitGrou
 	for {
 		select {
 		case <-timeout:
-			fmt.Print("TIMEOUT: ")
+			c.printf("TIMEOUT: ")
 			c.Status(service, false)
 			return
 		case <-tick:
 			status := newStatus(service, c.serviceName(service))
 			if status.Check(action, start) {
-				fmt.Println(status)
+				c.println(status)
 				return
 			}
 		}
@@ -326,7 +335,7 @@ func (c *ctl) Ctl(cmdStr string) bool {
 		return ctlCmd.Run(c, params)
 	}
 	if cmd == nil {
-		fmt.Printf("%s: unable to find action\n", params[0])
+		c.printf("%s: unable to find action\n", params[0])
 		return false
 	}
 	action := cmd.Action()
@@ -341,7 +350,7 @@ func (c *ctl) Ctl(cmdStr string) bool {
 		}
 		services := c.Services(param, false)
 		if len(services) == 0 {
-			fmt.Printf("%s: unable to find service\n", param)
+			c.printf("%s: unable to find service\n", param)
 			continue
 		}
 		for _, service := range services {
@@ -359,7 +368,7 @@ func (c *ctl) Ctl(cmdStr string) bool {
 func (c *ctl) Run() bool {
 	cmd, err := c.line.Prompt("svctl> ")
 	if err == io.EOF {
-		fmt.Println()
+		c.println()
 		return true
 	} else if err != nil {
 		log.Printf("error reading prompt contents: %s\n", err)
@@ -370,7 +379,7 @@ func (c *ctl) Run() bool {
 
 // main Creates svctl entry point, prints all processes statuses and launches event loop.
 func main() {
-	ctl := newCtl()
+	ctl := newCtl(os.Stdout)
 	defer ctl.Close()
 	ctl.Status("*", true)
 	for !ctl.Run() {

svctl_test.go

@@ -22,7 +22,6 @@
 package main
 
 import (
-	"bufio"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -54,6 +53,21 @@ func equal(s1, s2 []string) bool {
 	return true
 }
 
+type stdout struct {
+	value []string
+}
+
+func (s *stdout) Write(p []byte) (n int, err error) {
+	s.value = append(s.value, string(p)[:len(p)-1])
+	return len(p), nil
+}
+
+func (s *stdout) ReadString() string {
+	v := s.value[0]
+	s.value = s.value[1:]
+	return v
+}
+
 func createRunitDir() string {
 	dir, err := ioutil.TempDir("", "svctl_tests")
 	fatal(err)
@@ -67,8 +81,7 @@ type runitRunner struct {
 	runsvdir *exec.Cmd
 	zs       map[string]int
 
-	stdout     *bufio.Reader
-	realStdout *os.File
+	stdout *stdout
 }
 
 func newRunitRunner() *runitRunner {
@@ -77,14 +90,9 @@ func newRunitRunner() *runitRunner {
 	r := &runitRunner{
 		basedir: path.Join(dir, "_testdata"),
 		zs:      map[string]int{"r0": 0, "r1": 0, "o": 0},
+		stdout:  &stdout{},
 	}
 
-	stdr, stdw, err := os.Pipe()
-	fatal(err)
-	r.stdout = bufio.NewReader(stdr)
-	r.realStdout = os.Stdout
-	os.Stdout = stdw
-
 	r.runsvdir = exec.Command("runsvdir", "-P", r.basedir)
 	fatal(r.runsvdir.Start())
 	// Make sure runsvdir has enough time to scan the directories
@@ -97,17 +105,11 @@ func (r *runitRunner) Close() {
 	r.runsvdir.Process.Signal(syscall.SIGHUP)
 	r.runsvdir.Process.Wait()
 	os.RemoveAll(path.Dir(r.basedir))
-	os.Stdout.Close()
-	os.Stdout = r.realStdout
 }
 
 func (r *runitRunner) Assert(t *testing.T, cmd *cmdDef) {
 	for _, service := range cmd.services {
-		stdout, err := r.stdout.ReadString('\n')
-		if err != nil {
-			t.Errorf("ERROR READING `stdout`: `%s`", err)
-			continue
-		}
+		stdout := r.stdout.ReadString()
 		pieces := strings.Split(stdout, "   ")
 		if !contains(cmd.services, pieces[0]) {
 			t.Errorf(
@@ -172,12 +174,7 @@ func (r *runitRunner) Assert(t *testing.T, cmd *cmdDef) {
 }
 
 func (r *runitRunner) AssertError(t *testing.T, msg string) {
-	stdout, err := r.stdout.ReadString('\n')
-	if err != nil {
-		t.Errorf("ERROR READING `stdout`: `%s`", err)
-		return
-	}
-	stdout = stdout[:len(stdout)-1]
+	stdout := r.stdout.ReadString()
 	if stdout != msg {
 		t.Errorf("ERROR IN STATUS: `%s` != `%s`", stdout, msg)
 	}
@@ -192,7 +189,11 @@ type cmdDef struct {
 
 func TestCmd(t *testing.T) {
 	runit := newRunitRunner()
-	svctl := ctl{basedir: runit.basedir, line: liner.NewLiner()}
+	svctl := ctl{
+		line:    liner.NewLiner(),
+		basedir: runit.basedir,
+		stdout:  runit.stdout,
+	}
 
 	// Tests for correct usage.
 	cmds := []cmdDef{