public void ContainSpecificString(string digits, string expectedCombination)
{
var combinator = new LetterCombinator();
var result = combinator.LetterCombinations(digits);
Assert.Contains(result, v => string.Equals(v, expectedCombination, StringComparison.OrdinalIgnoreCase));
}
public void ReturnAllPossibleCombinations(string digits, IEnumerable <string> expected)
{
var combinator = new LetterCombinator();
var result = combinator.LetterCombinations(digits);
Assert.True(expected.SequenceEqual(result));
}