packer/plugin: Actually try more ports for plugins

packer/plugin/builder_test.go

+package plugin
+
+import (
+	"cgl.tideland.biz/asserts"
+	"github.com/mitchellh/packer/packer"
+	"os/exec"
+	"testing"
+)
+
+type helperBuilder byte
+
+func (helperBuilder) Prepare(interface{}) {}
+
+func (helperBuilder) Run(packer.Build, packer.Ui) {}
+
+func TestBuilder_NoExist(t *testing.T) {
+	assert := asserts.NewTestingAsserts(t, true)
+
+	_, err := Builder(exec.Command("i-should-never-ever-ever-exist"))
+	assert.NotNil(err, "should have an error")
+}
+
+func TestBuilder_Good(t *testing.T) {
+	assert := asserts.NewTestingAsserts(t, true)
+
+	_, err := Builder(helperProcess("builder"))
+	assert.Nil(err, "should start builder properly")
+}
+

packer/plugin/command_test.go

@@ -2,6 +2,7 @@ package plugin
 
 import (
 	"cgl.tideland.biz/asserts"
+	"github.com/mitchellh/packer/packer"
 	"os/exec"
 	"testing"
 )
@@ -9,6 +10,16 @@ import (
 // TODO: Test command cleanup functionality
 // TODO: Test timeout functionality
 
+type helperCommand byte
+
+func (helperCommand) Run(packer.Environment, []string) int {
+	return 42
+}
+
+func (helperCommand) Synopsis() string {
+	return "1"
+}
+
 func TestCommand_NoExist(t *testing.T) {
 	assert := asserts.NewTestingAsserts(t, true)
 
@@ -22,8 +33,11 @@ func TestCommand_Good(t *testing.T) {
 	command, err := Command(helperProcess("command"))
 	assert.Nil(err, "should start command properly")
 
-	result := command.Synopsis()
-	assert.Equal(result, "1", "should return result")
+	assert.NotNil(command, "should have a command")
+	if command != nil {
+		result := command.Synopsis()
+		assert.Equal(result, "1", "should return result")
+	}
 }
 
 func TestCommand_CommandExited(t *testing.T) {

packer/plugin/plugin.go

@@ -16,6 +16,7 @@ import (
 	"os"
 	packrpc "github.com/mitchellh/packer/packer/rpc"
 	"strconv"
+	"strings"
 )
 
 // This serves a single RPC connection on the given RPC server on
@@ -40,7 +41,14 @@ func serve(server *rpc.Server) (err error) {
 		address = fmt.Sprintf(":%d", port)
 		listener, err = net.Listen("tcp", address)
 		if err != nil {
-			return
+			if !strings.Contains(err.Error(), "address already in use") {
+				// Not an address already in use error, return.
+				return
+			} else {
+				// Address is in use, just try another
+				err = nil
+				continue
+			}
 		}
 
 		break
@@ -67,6 +75,18 @@ func serve(server *rpc.Server) (err error) {
 	return
 }
 
+// Serves a builder from a plugin.
+func ServeBuilder(builder packer.Builder) {
+	log.Println("Preparing to serve a builder plugin...")
+
+	server := rpc.NewServer()
+	packrpc.RegisterBuilder(server, builder)
+
+	if err := serve(server); err != nil {
+		log.Panic(err)
+	}
+}
+
 // Serves a command from a plugin.
 func ServeCommand(command packer.Command) {
 	log.Println("Preparing to serve a command plugin...")

packer/plugin/plugin_test.go

@@ -2,23 +2,12 @@ package plugin
 
 import (
 	"fmt"
-	"github.com/mitchellh/packer/packer"
 	"os"
 	"os/exec"
 	"testing"
 	"time"
 )
 
-type helperCommand byte
-
-func (helperCommand) Run(packer.Environment, []string) int {
-	return 42
-}
-
-func (helperCommand) Synopsis() string {
-	return "1"
-}
-
 func helperProcess(s... string) *exec.Cmd {
 	cs := []string{"-test.run=TestHelperProcess", "--"}
 	cs = append(cs, s...)
@@ -59,6 +48,8 @@ func TestHelperProcess(*testing.T) {
 
 	cmd, args := args[0], args[1:]
 	switch cmd {
+	case "builder":
+		ServeBuilder(new(helperBuilder))
 	case "command":
 		ServeCommand(new(helperCommand))
 	case "invalid-rpc-address":

packer/rpc/builder_test.go

@@ -43,7 +43,7 @@ func TestBuilderRPC(t *testing.T) {
 
 	// Test Prepare
 	config := 42
-	bClient := &Builder{client}
+	bClient := Builder(client)
 	bClient.Prepare(config)
 	assert.True(b.prepareCalled, "prepare should be called")
 	assert.Equal(b.prepareConfig, 42, "prepare should be called with right arg")
@@ -68,7 +68,7 @@ func TestBuilder_ImplementsBuild(t *testing.T) {
 	assert := asserts.NewTestingAsserts(t, true)
 
 	var realBuilder packer.Builder
-	b := &Builder{nil}
+	b := Builder(nil)
 
 	assert.Implementor(b, &realBuilder, "should be a Builder")
 }