public void RetrieveAllWords_WhenGiveAFilePath_ShouldCallFileWrapperWithSameString() { var moqFileWrapper = new Mock<IFileWrapper>(); moqFileWrapper.Setup(m => m.ReadFile(It.IsAny<string>())).Returns(new List<string>()); var target = new WordService(moqFileWrapper.Object); target.RetrieveAllWordsToConsole(string.Empty); moqFileWrapper.Verify(m => m.ReadFile(It.IsAny<string>()), Times.Once); }