public void DocumentNumber_Method() { Assert.Throws<ArgumentNullException>(() => new LawsLawApiCall().DocumentNumber(null)); Assert.Throws<ArgumentException>(() => new LawsLawApiCall().DocumentNumber(string.Empty)); var call = new LawsLawApiCall(); Assert.False(call.Parameters.ContainsKey("document_number")); Assert.True(ReferenceEquals(call.DocumentNumber("documentNumber"), call)); Assert.Equal("documentNumber", call.Parameters["document_number"]); }