Merge pull request #58 from davidovich/davidovich/issue57

feature: Add a global debug switch

cmd/root.go

@@ -48,6 +48,7 @@ type mainCmd struct {
 	json     string
 	jsonFile string
 	raw      bool
+	debug    bool
 	out      io.Writer
 	osArgs   *[]string
 }
@@ -113,6 +114,7 @@ func CreateRootCmd(driver *summon.Driver, args []string) *cobra.Command {
 
 	rootCmd.PersistentFlags().StringVar(&main.json, "json", "", "json to use to render template")
 	rootCmd.PersistentFlags().StringVar(&main.jsonFile, "json-file", "", "json file to use to render template, with '-' for stdin")
+	rootCmd.PersistentFlags().BoolVarP(&main.debug, "debug", "d", false, "print debug info on stderr")
 	rootCmd.Flags().BoolVarP(&main.copyAll, "all", "a", false, "restitute all data")
 	rootCmd.Flags().BoolVar(&main.raw, "raw", false, "output without any template rendering")
 	rootCmd.Flags().StringVarP(&main.dest, "out", "o", config.OutputDir, "destination directory, or '-' for stdout")

cmd/run.go

@@ -15,6 +15,7 @@ type runCmdOpts struct {
 	driver summon.ConfigurableRunner
 	ref    string
 	args   []string
+	dryrun bool
 }
 
 func newRunCmd(driver summon.ConfigurableRunner, main *mainCmd) *cobra.Command {
@@ -43,6 +44,8 @@ func newRunCmd(driver summon.ConfigurableRunner, main *mainCmd) *cobra.Command {
 		Run:                func(cmd *cobra.Command, args []string) {},
 	}
 
+	rcmd.PersistentFlags().BoolVarP(&runCmd.dryrun, "dry-run", "n", false, "only show what would be executed")
+
 	subRunE := func(cmd *cobra.Command, args []string) error {
 		cmd.SilenceUsage = true
 
@@ -103,6 +106,8 @@ func (r *runCmdOpts) run() error {
 		summon.Ref(r.ref),
 		summon.Args(r.args...),
 		summon.JSON(r.json),
+		summon.Debug(r.debug),
+		summon.DryRun(r.dryrun),
 	)
 
 	if err != nil {

cmd/run_test.go

@@ -21,6 +21,7 @@ func TestRunCmd(t *testing.T) {
 		args      []string
 		main      *mainCmd
 		wantError bool
+		noCalls   bool
 	}{
 		{
 			desc: "sub-command",
@@ -47,9 +48,15 @@ func TestRunCmd(t *testing.T) {
 			out:       "bash echo hello david --unknown-arg last params",
 			wantError: false,
 		},
+		{
+			desc:      "dry-run",
+			args:      []string{"echo", "-n"},
+			wantError: false,
+			noCalls:   true,
+		},
 	}
 
-	for _, tC := range testCases {
+	for _, tC := range testCases[4:] {
 		t.Run(tC.desc, func(t *testing.T) {
 			s, _ := summon.New(box)
 			stdout := &bytes.Buffer{}
@@ -74,7 +81,11 @@ func TestRunCmd(t *testing.T) {
 
 			c, err := testutil.GetCalls(stderr)
 			assert.Nil(t, err)
-			assert.Contains(t, c.Calls[0].Args, tC.out)
+			if tC.noCalls {
+				assert.Len(t, c.Calls, 0)
+			} else {
+				assert.Contains(t, c.Calls[0].Args, tC.out)
+			}
 		})
 	}
 }

pkg/summon/options.go

@@ -28,6 +28,10 @@ type options struct {
 	out io.Writer
 	// raw disables template rendering
 	raw bool
+	// debug enables printing debug info
+	debug bool
+	// dryrun disables any command execution
+	dryrun bool
 	// execCommand overrides the command used to run external processes
 	execCommand command.ExecCommandFn
 }
@@ -60,6 +64,22 @@ func All(all bool) Option {
 	}
 }
 
+// Debug prints debugging info on stderr
+func Debug(enable bool) Option {
+	return func(opts *options) error {
+		opts.debug = enable
+		return nil
+	}
+}
+
+// DryRun does not run the command
+func DryRun(enable bool) Option {
+	return func(opts *options) error {
+		opts.dryrun = enable
+		return nil
+	}
+}
+
 // Filename sets the requested filename in the boxed data.
 func Filename(filename string) Option {
 	return func(opts *options) error {

pkg/summon/run.go

@@ -52,11 +52,23 @@ func (d *Driver) Run(opts ...Option) error {
 	}
 
 	cmd := d.execCommand(eu.invoker, rargs...)
-	cmd.Stdin = os.Stdin
-	cmd.Stdout = os.Stdout
-	cmd.Stderr = os.Stderr
 
-	return cmd.Run()
+	if d.opts.debug || d.opts.dryrun {
+		msg := "Executing"
+		if d.opts.dryrun {
+			msg = "Would execute"
+		}
+		fmt.Fprintf(os.Stderr, "%s `%s`...\n", msg, cmd.Args)
+	}
+
+	if !d.opts.dryrun {
+		cmd.Stdin = os.Stdin
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+
+		return cmd.Run()
+	}
+	return nil
 }
 
 // ListInvocables lists the invocables in the config file under the exec: