Add skeleton for collapse command

This includes some boilerplate for the testing setup as well

cmd/collapse.go

@@ -0,0 +1,34 @@
+package cmd
+
+import (
+	"encoding/json"
+
+	"github.com/circleci/circleci-cli/filetree"
+	"github.com/spf13/cobra"
+)
+
+var collapseCommand = &cobra.Command{
+	Use:   "collapse",
+	Short: "Collapse your CircleCI configuration to a single file",
+	Run:   collapse,
+}
+
+var root string
+
+func init() {
+	collapseCommand.Flags().StringVarP(&root, "root", "r", ".circleci", "path to your configuration (default is .circleci)")
+	// TODO: Add flag for excluding paths
+}
+
+func collapse(cmd *cobra.Command, args []string) {
+	tree, err := filetree.NewTree(root)
+	if err != nil {
+		Logger.FatalOnError("An error occurred", err)
+	}
+
+	data, err := json.MarshalIndent(tree, "", "  ")
+	if err != nil {
+		Logger.FatalOnError("An error occurred trying to marshal", err)
+	}
+	Logger.Infoln(data)
+}

cmd/collapse_test.go

@@ -0,0 +1,53 @@
+package cmd_test
+
+import (
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+	"github.com/onsi/gomega/gbytes"
+	"github.com/onsi/gomega/gexec"
+)
+
+var _ = Describe("collapse", func() {
+	var (
+		tempRoot string
+		command  *exec.Cmd
+	)
+
+	BeforeEach(func() {
+		var err error
+		tempRoot, err = ioutil.TempDir("", "circleci-cli-test-")
+		Expect(err).ToNot(HaveOccurred())
+
+		command = exec.Command(pathCLI, "collapse", "-r", tempRoot)
+	})
+
+	AfterEach(func() {
+		Expect(os.RemoveAll(tempRoot)).To(Succeed())
+	})
+
+	Describe("with a single file under root", func() {
+		BeforeEach(func() {
+			var err error
+			_, err = os.OpenFile(
+				filepath.Join(tempRoot, "foo"),
+				os.O_RDWR|os.O_CREATE,
+				0600,
+			)
+			Expect(err).ToNot(HaveOccurred())
+		})
+
+		It("Prints a JSON tree of the nested file-structure", func() {
+			session, err := gexec.Start(command, GinkgoWriter, GinkgoWriter)
+			Expect(err).ShouldNot(HaveOccurred())
+			Eventually(session.Err.Contents()).Should(BeEmpty())
+
+			Eventually(session.Out).Should(gbytes.Say("{}"))
+			Eventually(session).Should(gexec.Exit(0))
+		})
+	})
+})

cmd/root.go

@@ -33,6 +33,7 @@ var rootCmd = &cobra.Command{
 func addCommands() {
 	rootCmd.AddCommand(diagnosticCmd)
 	rootCmd.AddCommand(queryCmd)
+	rootCmd.AddCommand(collapseCommand)
 	rootCmd.AddCommand(configureCommand)
 }