Add basic command implementation

command/command.go

+package command
+
+import (
+	"fmt"
+	"os"
+)
+
+type cmdfunc func() error
+
+type Commands struct {
+	cmds map[string]cmdfunc
+}
+
+func DebugCommands() *Commands {
+	cmds := map[string]cmdfunc{
+		"exit": exitFunc,
+	}
+
+	return &Commands{cmds}
+}
+
+func (c *Commands) Find(cmdstr string) cmdfunc {
+	cmd, ok := c.cmds[cmdstr]
+	if !ok {
+		return noCmdAvailable
+	}
+
+	return cmd
+}
+
+func noCmdAvailable() error {
+	return fmt.Errorf("command not available")
+}
+
+func exitFunc() error {
+	os.Exit(0)
+	return nil
+}

command/command_test.go

+package command
+
+import "testing"
+
+func TestCommandDefault(t *testing.T) {
+	var (
+		cmds = Commands{make(map[string]cmdfunc)}
+		cmd  = cmds.Find("non-existant-command")
+	)
+
+	err := cmd()
+	if err == nil {
+		t.Fatal("cmd() did not default")
+	}
+
+	if err.Error() != "command not available" {
+		t.Fatal("wrong command output")
+	}
+}