Merge pull request #45 from waterlink/add-new-cf-command-flavor-where-stdin-buffer-can-be-provided

Allow instantiating a CF command with provided STDIN buffer.

[finishes #167944101](https://www.pivotaltracker.com/story/show/167944101)

Author: davewalter

cf/cf.go

@@ -1,6 +1,8 @@
 package cf
 
 import (
+	"io"
+
 	"github.com/cloudfoundry-incubator/cf-test-helpers/commandstarter"
 	"github.com/cloudfoundry-incubator/cf-test-helpers/internal"
 	"github.com/cloudfoundry-incubator/cf-test-helpers/silentcommandstarter"
@@ -29,3 +31,14 @@ var CfRedact = func(stringToRedact string, args ...string) *gexec.Session {
 
 	return internal.CfWithCustomReporter(cmdStarter, redactingReporter, args...)
 }
+
+// CfWithStdin can be used to prepare arbitrary terminal input from the user in the tests.
+// Here is an example of how it can be used:
+//
+// inputConfirmingPrompt := bytes.NewBufferString("yes\n")
+// session := cf.CfWithStdin(inputConfirmingPrompt, "update-service", "my-service", "--upgrade")
+// Eventually(session).Should(Exit(0))
+var CfWithStdin = func(stdin io.Reader, args ...string) *gexec.Session {
+	cmdStarter := commandstarter.NewCommandStarterWithStdin(stdin)
+	return internal.Cf(cmdStarter, args...)
+}

commandstarter/command_starter.go

@@ -1,6 +1,7 @@
 package commandstarter
 
 import (
+	"io"
 	"os/exec"
 	"time"
 
@@ -10,14 +11,22 @@ import (
 )
 
 type CommandStarter struct {
+	stdin io.Reader
 }
 
 func NewCommandStarter() *CommandStarter {
 	return &CommandStarter{}
 }
 
+func NewCommandStarterWithStdin(stdin io.Reader) *CommandStarter {
+	return &CommandStarter{
+		stdin: stdin,
+	}
+}
+
 func (r *CommandStarter) Start(reporter internal.Reporter, executable string, args ...string) (*gexec.Session, error) {
 	cmd := exec.Command(executable, args...)
+	cmd.Stdin = r.stdin
 	reporter.Report(time.Now(), cmd)
 
 	return gexec.Start(cmd, ginkgo.GinkgoWriter, ginkgo.GinkgoWriter)

commandstarter/command_starter_test.go

@@ -1,13 +1,16 @@
 package commandstarter_test
 
 import (
+	"bytes"
+	"io"
 	"os/exec"
 	"time"
 
 	"github.com/cloudfoundry-incubator/cf-test-helpers/commandstarter"
 
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
+	. "github.com/onsi/gomega/gbytes"
 )
 
 type fakeReporter struct {
@@ -32,7 +35,25 @@ var _ = Describe("CommandStarter", func() {
 	})
 
 	It("reports the command that it's running", func() {
-		cmdStarter.Start(reporter, "bash", "-c", "echo \"hello world\"")
+		session, err := cmdStarter.Start(reporter, "bash", "-c", "echo \"hello world\"")
+		Expect(err).To(Succeed())
 		Expect(reporter.calledWith.cmd.Args).To(Equal([]string{"bash", "-c", "echo \"hello world\""}))
+		Eventually(session).Should(Say("hello world"))
+	})
+
+	When("created with stdin", func() {
+		var stdin io.Reader
+
+		BeforeEach(func() {
+			stdin = bytes.NewBufferString("name from input")
+			cmdStarter = commandstarter.NewCommandStarterWithStdin(stdin)
+		})
+
+		It("reports what command is running and sends the input to the command", func() {
+			session, err := cmdStarter.Start(reporter, "bash", "-c", `echo "hello $(cat -)"`)
+			Expect(err).To(Succeed())
+			Expect(reporter.calledWith.cmd.Args).To(Equal([]string{"bash", "-c", `echo "hello $(cat -)"`}))
+			Eventually(session).Should(Say("hello name from input"))
+		})
 	})
 })