public void Add_WhenCalledWithExistingKey_ThrowsDuplicateKeyException()
{
// Arrange
var configItems = new List <IConfigItem>()
{
new ConfigItem("key1", "value1"),
new ConfigItem("key2", "value2"),
new ConfigItem("key3", "value3"),
};
var item = new ConfigItem("key1", "value1");
_fileManager.ReadAllEntriesFromFile().Returns(configItems);
_memoryCacheService.Contains(item.key).Returns(true);
_configurationService = new ConfigurationService(_fileManager, _memoryCacheService);
// Act
Assert.Throws <DuplicateKeyException>(() => _configurationService.Add(item));
// Assert
_memoryCacheService.DidNotReceive().Add(item);
_fileManager.DidNotReceive().AddEntry(Arg.Any <ConfigItem>());
}
