diff --git a/store.go b/store.go
index b1016b1..86d18cf 100644
--- a/store.go
+++ b/store.go
@@ -166,6 +166,7 @@ func (u User) merge(updates User) (User, error) {
 }
 
 var ErrShareNotFound = errors.New("share not found")
+var ErrLoginDuplicate = errors.New("login already exists")
 
 func (store *DBStore) AddUser(user User) (err error) {
 	if strings.Contains(user.Username, ":") {
diff --git a/store_test.go b/store_test.go
index a32b861..fecf480 100644
--- a/store_test.go
+++ b/store_test.go
@@ -186,6 +186,100 @@ func TestStoreShareHandling(t *testing.T) {
 		})
 	})
 
+	t.Run("share access should work", func(t *testing.T) {
+		share1, _ := store.CreateShare()
+		share2, _ := store.CreateShare()
+		share3, _ := store.CreateShare()
+
+		user1 := User{Username: "user1"}
+		user2 := User{Username: "user2"}
+		_ = store.AddUser(user1)
+		_ = store.AddUser(user2)
+
+		t.Run("multiple shares should exist", func(t *testing.T) {
+			shares, _ := store.GetShares()
+			if len(shares) != 3 {
+				t.Errorf("3 shares should exist")
+			}
+		})
+
+		t.Run("can add users to shares", func(t *testing.T) {
+			if err := store.AddUserToShare(share1, user1.Username, ShareRoleAdmin); err != nil {
+				t.Errorf("cannot add user1 to share1: %v", err)
+			}
+			if err := store.AddUserToShare(share1, user2.Username, ShareRoleReader); err != nil {
+				t.Errorf("cannot add user2 to share1: %v", err)
+			}
+			if err := store.AddUserToShare(share2, user2.Username, ShareRoleAdmin); err != nil {
+				t.Errorf("cannot add user2 to share2: %v", err)
+			}
+
+			t.Run("cannot add login if user doesn't exist", func(t *testing.T) {
+				if err := store.AddLogin(share3, user1.Username, Login{"foo", ""}); err == nil {
+					t.Errorf("an error should have been returned")
+				} else if err != ErrUserNotFound {
+					t.Errorf("wrong error has been returned: %v", err)
+				}
+			})
+
+			t.Run("logins can be added", func(t *testing.T) {
+				login1 := Login{LoginName: "login1"}
+				login2 := Login{LoginName: "login2"}
+				login3 := Login{LoginName: "login3"}
+
+				if err := store.AddLogin(share1, user1.Username, login1); err != nil {
+					t.Errorf("adding login returned error: %v", err)
+				}
+				if err := store.AddLogin(share1, user2.Username, login2); err != nil {
+					t.Errorf("adding login returned error: %v", err)
+				}
+				if err := store.AddLogin(share1, user2.Username, login3); err != nil {
+					t.Errorf("adding login returned error: %v", err)
+				}
+
+				t.Run("duplicate login not allowed", func(t *testing.T) {
+					if err := store.AddLogin(share1, user2.Username, login1); err != ErrLoginDuplicate {
+						t.Errorf("unexpected error: %v", err)
+					}
+				})
+
+				t.Run("share is found by login", func(t *testing.T) {
+					share, err := store.FindByLogin(user1.Username, login1.LoginName)
+					if err != nil {
+						t.Errorf("unexpected error: %v", err)
+					}
+					if share.UUID != share1.UUID {
+						t.Errorf("wrong store returned")
+					}
+				})
+
+				t.Run("unknown login/share combination returns error", func(t *testing.T) {
+					if _, err := store.FindByLogin(user1.Username, login3.LoginName); err != ErrShareNotFound {
+						t.Errorf("unexpected error: %v", err)
+					}
+				})
+
+				t.Run("login can be removed", func(t *testing.T) {
+					if err := store.RemoveLogin(share1, user1.Username, login1.LoginName); err != nil {
+						t.Errorf("unexpected error: %v", err)
+					}
+					if _, err := store.FindByLogin(user1.Username, login1.LoginName); err != ErrShareNotFound {
+						t.Errorf("share should not be found now, but returned: %v", err)
+					}
+				})
+
+				t.Run("user can be removed", func(t *testing.T) {
+					if err := store.RemoveUserFromShare(share2, user2.Username); err != nil {
+						t.Errorf("unexpected error: %v", err)
+					}
+					if _, err := store.FindByLogin(user2.Username, login2.LoginName); err != ErrShareNotFound {
+						t.Errorf("share should not be found now, but returned: %v", err)
+					}
+				})
+			})
+		})
+	})
+
 	t.Run("database should be empty now", func(t *testing.T) {
 		// checks that we properly deleted all keys
 		if err := store.db.View(func(tx *buntdb.Tx) error {