[CLI-62] cli command to list tenants available

internal/cli/tenants.go

@@ -2,6 +2,8 @@ package cli
 
 import (
 	"fmt"
+	"github.com/olekukonko/tablewriter"
+	"os"
 
 	"github.com/auth0/auth0-cli/internal/prompt"
 	"github.com/spf13/cobra"
@@ -14,9 +16,41 @@ func tenantsCmd(cli *cli) *cobra.Command {
 	}
 
 	cmd.AddCommand(useTenantCmd(cli))
+	cmd.AddCommand(listTenantCmd(cli))
 	return cmd
 }
 
+func listTenantCmd(cli *cli) *cobra.Command {
+	cmd := &cobra.Command{
+		Use: "list",
+		Short: "List your tenants",
+		Long: `auth0 tenants list`,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			listTenant, err := cli.listTenants()
+			if err != nil {
+				return fmt.Errorf("Unable to load tenants due to an unexpected error: %w", err)
+			}
+
+			tenNames := make([]string, len(listTenant))
+			for i, t := range listTenant {
+				tenNames[i] = t.Name
+			}
+
+			table := tablewriter.NewWriter(os.Stdout)
+			table.SetHeader([]string{"Available tenants"})
+			for _, val := range tenNames {
+				b := []string{val}
+				table.Append(b)
+			}
+
+			table.Render()
+			return nil
+		},
+	}
+	return cmd
+}
+
+
 func useTenantCmd(cli *cli) *cobra.Command {
 	cmd := &cobra.Command{
 		Use:     "use",