fix: add check for equality of fetched teams and renamed teams

cmd/cli/teams_names.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -17,6 +18,9 @@ const (
 	teamsByNamesKey = "moira-teams-by-names"
 )
 
+var errTeamsCountAndUniqueNamesCountMismatch = errors.New(
+	"count of teams does not match count of unique names after transformation")
+
 // fillTeamNamesHash does the following
 //  1. Get all teams from DB.
 //  2. Group teams with same names.
@@ -46,6 +50,10 @@ func fillTeamNamesHash(logger moira.Logger, database moira.Database) error {
 
 		teamByUniqueName := transformTeamsByNameMap(teamsByNameMap)
 
+		if len(teamByUniqueName) != len(teamsMap) {
+			return errTeamsCountAndUniqueNamesCountMismatch
+		}
+
 		client := db.Client()
 		ctx := db.Context()