public void BuildPdfShouldThrowErrorWithNullInput()
{
//Arrange
this.configurationSection.Setup(cs => cs.Value).Returns("fakeoutput");
this.configuration.Setup(c => c.GetSection(It.IsAny <string>())).Returns(configurationSection.Object);
var expectedErrorMessage = Constants.NO_COMMANDS_TO_PROCESS_ERROR;
var pdfGenerator = new PdfGenerator(configuration.Object);
//Act (see Assertion)
//Assert
var error = Assert.Throws <ArgumentException>(() => pdfGenerator.BuildPdf(null));
Assert.AreEqual(expectedErrorMessage, error.Message);
}