user: improve error handling on New

Related to #183.

user/user.go

@@ -1,4 +1,4 @@
-// Copyright 2014 gandalf authors. All rights reserved.
+// Copyright 2015 gandalf authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
@@ -20,7 +20,12 @@ func init() {
 	log.Init()
 }
 
-var ErrUserNotFound = errors.New("User not found")
+var (
+	ErrUserAlreadyExists = errors.New("user already exists")
+	ErrUserNotFound      = errors.New("user not found")
+
+	userNameRegexp = regexp.MustCompile(`\s|[^aA-zZ0-9-+.@]|(^$)`)
+)
 
 type User struct {
 	Name string `bson:"_id"`
@@ -43,22 +48,17 @@ func New(name string, keys map[string]string) (*User, error) {
 	defer conn.Close()
 	if err := conn.User().Insert(&u); err != nil {
 		if mgo.IsDup(err) {
-			log.Errorf("user.New: %q duplicate user", name)
-			return u, errors.New("Could not create user: user already exists")
+			return nil, ErrUserAlreadyExists
 		}
 		log.Errorf("user.New: %s", err)
-		return u, err
+		return nil, err
 	}
 	return u, addKeys(keys, u.Name)
 }
 
 func (u *User) isValid() (isValid bool, err error) {
-	m, err := regexp.Match(`\s|[^aA-zZ0-9-+.@]|(^$)`, []byte(u.Name))
-	if err != nil {
-		panic(err)
-	}
-	if m {
-		return false, errors.New("Validation Error: user name is not valid")
+	if userNameRegexp.MatchString(u.Name) {
+		return false, &InvalidUserError{message: "username is not valid"}
 	}
 	return true, nil
 }
@@ -151,3 +151,11 @@ func RemoveKey(uName, kName string) error {
 	}
 	return removeKey(kName, uName)
 }
+
+type InvalidUserError struct {
+	message string
+}
+
+func (err *InvalidUserError) Error() string {
+	return err.message
+}

user/user_test.go

@@ -84,8 +84,8 @@ func (s *S) TestNewDuplicateUser(c *check.C) {
 	c.Assert(err, check.IsNil)
 	defer conn.User().Remove(bson.M{"_id": u.Name})
 	defer conn.Key().Remove(bson.M{"name": "somekey"})
-	u, err = New("someuser", map[string]string{"somekey": rawKey})
-	c.Assert(err, check.ErrorMatches, "Could not create user: user already exists")
+	_, err = New("someuser", map[string]string{"somekey": rawKey})
+	c.Assert(err, check.Equals, ErrUserAlreadyExists)
 }
 
 func (s *S) TestNewDuplicateUserDifferentKey(c *check.C) {
@@ -95,8 +95,8 @@ func (s *S) TestNewDuplicateUserDifferentKey(c *check.C) {
 	c.Assert(err, check.IsNil)
 	defer conn.User().Remove(bson.M{"_id": u.Name})
 	defer conn.Key().Remove(bson.M{"name": "somekey"})
-	u, err = New("someuser", map[string]string{"somedifferentkey": rawKey + "fakeKey"})
-	c.Assert(err, check.ErrorMatches, "Could not create user: user already exists")
+	_, err = New("someuser", map[string]string{"somedifferentkey": rawKey + "fakeKey"})
+	c.Assert(err, check.Equals, ErrUserAlreadyExists)
 }
 
 func (s *S) TestNewUserShouldStoreUserInDatabase(c *check.C) {
@@ -117,9 +117,9 @@ func (s *S) TestNewUserShouldStoreUserInDatabase(c *check.C) {
 func (s *S) TestNewChecksIfUserIsValidBeforeStoring(c *check.C) {
 	_, err := New("", map[string]string{})
 	c.Assert(err, check.NotNil)
-	got := err.Error()
-	expected := "Validation Error: user name is not valid"
-	c.Assert(got, check.Equals, expected)
+	e, ok := err.(*InvalidUserError)
+	c.Assert(ok, check.Equals, true)
+	c.Assert(e.message, check.Equals, "username is not valid")
 }
 
 func (s *S) TestNewWritesKeyInAuthorizedKeys(c *check.C) {