void OnlyWhenCountryCodeExists_ThenValidationPasses(string code, bool expected)
{
bool codeExists(string c) =>
new [] { "it", "in", "ir" }.Contains(c);
var actual = Countries.CodeIsValid(codeExists, code);
Assert.Equal(expected, actual);
}
void WhenCodeHasIncorrectFormat_ThenItsExistenceIsNotChecked()
{
// can also achieve this by refactoring the previous test
// to take an additional parameter
Func <string, bool> codeExists = c =>
{
Assert.True(false);
return(true);
};
var actual = Countries.CodeIsValid(codeExists, "i");
Assert.False(actual);
}