No momento que fui fazer a migração apareceu isso:
An attempt to attach an auto-named database for file C:\Users\lucas\Documents\Visual Studio 2015\Projects\lojaComEntity\lojaComEntity\bin\Debug\loja.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.
Segue minha app.cofig :
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
</configSections>
<connectionStrings>
<add name="lojaConnectionString"
connectionString="Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\loja.mdf;Integrated Security=True;Connect Timeout=30"
providerName="System.Data.SqlClient" />
</connectionStrings>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
</startup>
</configuration>