Update version command

command/version.go

@@ -1,18 +1,55 @@
 package command
 
 import (
+	"strings"
+
 	"github.com/hashicorp/vault/version"
 	"github.com/mitchellh/cli"
+	"github.com/posener/complete"
 )
 
+// Ensure we are implementing the right interfaces.
+var _ cli.Command = (*VersionCommand)(nil)
+var _ cli.CommandAutocomplete = (*VersionCommand)(nil)
+
 // VersionCommand is a Command implementation prints the version.
 type VersionCommand struct {
+	*BaseCommand
+
 	VersionInfo *version.VersionInfo
-	Ui          cli.Ui
+}
+
+func (c *VersionCommand) Synopsis() string {
+	return "Prints the Vault CLI version"
 }
 
 func (c *VersionCommand) Help() string {
-	return ""
+	helpText := `
+Usage: vault version
+
+  Prints the version of this Vault CLI. This does not print the target Vault
+  server version.
+
+  Print the version:
+
+      $ vault version
+
+  There are no arguments or flags to this command. Any additional arguments or
+  flags are ignored.
+`
+	return strings.TrimSpace(helpText)
+}
+
+func (c *VersionCommand) Flags() *FlagSets {
+	return nil
+}
+
+func (c *VersionCommand) AutocompleteArgs() complete.Predictor {
+	return nil
+}
+
+func (c *VersionCommand) AutocompleteFlags() complete.Flags {
+	return nil
 }
 
 func (c *VersionCommand) Run(_ []string) int {
@@ -20,10 +57,6 @@ func (c *VersionCommand) Run(_ []string) int {
 	if version.CgoEnabled {
 		out += " (cgo)"
 	}
-	c.Ui.Output(out)
+	c.UI.Output(out)
 	return 0
 }
-
-func (c *VersionCommand) Synopsis() string {
-	return "Prints the Vault version"
-}

command/version_test.go

@@ -1,11 +1,48 @@
 package command
 
 import (
+	"strings"
 	"testing"
 
+	"github.com/hashicorp/vault/version"
 	"github.com/mitchellh/cli"
 )
 
-func TestVersionCommand_implements(t *testing.T) {
-	var _ cli.Command = &VersionCommand{}
+func testVersionCommand(tb testing.TB) (*cli.MockUi, *VersionCommand) {
+	tb.Helper()
+
+	ui := cli.NewMockUi()
+	return ui, &VersionCommand{
+		VersionInfo: &version.VersionInfo{},
+		BaseCommand: &BaseCommand{
+			UI: ui,
+		},
+	}
+}
+
+func TestVersionCommand_Run(t *testing.T) {
+	t.Parallel()
+
+	t.Run("output", func(t *testing.T) {
+		t.Parallel()
+
+		ui, cmd := testVersionCommand(t)
+		code := cmd.Run(nil)
+		if exp := 0; code != exp {
+			t.Errorf("expected %d to be %d", code, exp)
+		}
+
+		expected := "Vault"
+		combined := ui.OutputWriter.String() + ui.ErrorWriter.String()
+		if !strings.Contains(combined, expected) {
+			t.Errorf("expected %q to equal %q", combined, expected)
+		}
+	})
+
+	t.Run("no_tabs", func(t *testing.T) {
+		t.Parallel()
+
+		_, cmd := testVersionCommand(t)
+		assertNoTabs(t, cmd)
+	})
 }