Programming Alexa Skills for the Amazon Echo

76 Pages·2017·6.11 MB·English

iMessages, F# Type Providers, Swagger, Cordova
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Xamarin versus Cordova
Azure Skyline and Docker
Accessing Data with F# Type Providers

TABLE OF CONTENTS
Features
8 Data-Driven Testing with Visual Studio 56 How to Know Your Team is Productive and
Delivering Quality
Does the idea of using an app that’s never been tested give you the willies?
It should, and Paul talks about finding the sticking points so you can be
Jeffrey takes a look at the state of the industry and comes up with
confident that your code works as intended before someone fires it up.
some interesting ways to measure efficiency and accuracy.
Paul Sheriff
Jeffrey Palermo
14 Xamarin versus Cordova
62 Exploring Sticker Packs with iOS 10
These days, you can’t target only one platform with your innovative apps.
Sticker packs and emojis are used by everyone from teenagers
They have to look good on many types of devices and operating systems.
to developers. Jason shows you how these simple tools can be more
Sahil looks at how Xamarin and Cordova translate into native apps and
than a basic form of communication.
how you can use a combination to build even more versatile systems
Jason Bender
than ever before.
Sahil Malik
66 Azure Skyline: Building and Deploying Services to
20 Legal Notes: Selecting and Operating a Legal Azure with .NET Core and Docker
Entity for Your User Group
Today’s devs have to be nimble. Your app has to work on a multitude
of platforms and meet any number of platform-specific demands.
Your user group has some serious experts in it and it’s time to share
Mike explains how a new tool called Docker can help you deploy
the knowledge. If your group wants to host conferences, offer classes,
your apps on everything from Linux to .NET and leave you hardly
or even go into business, you’ll want John’s advice about what you need
breaking a sweat.
to start the process.
Mike Yeager
John Petersen
22 Programming Alexa Skills for the Amazon Echo
Columns
If you’re looking for a way to computerize your home or add voice controls
to your apps, you’re interested in what’s happening with Amazon Echo.
Chris introduces you to some basic programming skills for the device and
points the way to greatness.
74 Managed Coder: On Coding Management
Chris Williams
Ted Neward
38 Creating iMessages Apps
Did you ever think you’d be programming apps without code?
Departments
Mohammad show you how, using Apple’s iMessages framework,
iOS 10, a little bit of Swift, and some Sticker Packs.
Mohammad Azam
6 Editorial
48 Accessing Your Data with F# Type Providers
You can access just about any data with type providers, whether in XML,
11 Advertisers Index
JSON, or APIs. Rachel shows us how, plus a nifty new Swagger type provider.
Rachel Reese
73 Code Compilers
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44
Table of Contents ccooddeemmaagg..ccoomm

OEDNILTIONREI AQLUICK ID 00
You’re Not Finished Yet
I’ve edited a whole lot of books, articles, help files, websites, and white papers about technology. I’ve
seen countless products come and go and I’ve been on plenty of teams building apps or software. At the
end of the day, there’s one thing I’m sure of: Everything needs to be tested before it’s sent out the door,
whether it’s the software, the device, or the words. The whole reason for ZD Labs’ existence was to Whether you rush to add those features or not,
Not only will your product (or article, etc.) be bet- find out whether products kept the promises on it’s important to consider that your tester (edi-
ter, but you’ll grow, too. their boxes, and to see if a reasonable amount of tor) won’t be the only person to have those
use or abuse might break them. We set benchmarks thoughts. They’re merely the first. You need to
Editing text is different from testing software, but to compare similar products or functions, and we consider the cost of delivering something that
it’s the same principle. You want users to effort- brought in freelancers with widely varied skill sets to might easily be seen as incomplete, even if you
lessly read the words and use the product. You need see how much knowledge was needed to succeed— disagree.
to know if the dialog box you see as the gateway to or fail. Our purpose wasn’t to help the manufactur-
your product contains a mystifying set of text boxes ers, although that was probably a result. We were I’ve seen more unpolished text than software as
or if the search function produces random results. trying to inform magazine readers so they could an editor, but it works the same way. If you’re
You don’t want people to struggle to use your prod- make intelligent purchases and use the products in writing the help files or UI, or even a nice article,
uct; you want a clear flow of information or func- an advantageous way. it’s important that your first reader understands
tion, and clear help files in case they get stuck. exactly what you mean. Instructions are not the
No matter how brilliant you are as a software de- time to get fancy or play with hyperbole or other
I once worked at ZD Labs, which supported all 12 signer, you need someone to be your first user who literary devices. Oh, you’re welcome to be humor-
of Ziff-Davis Publishing’s tech magazines. Our group can provide the kind of feedback that helps you de- ous, clever, or even charming (if you are those
took hardware and software and did our best to liver a great product before it goes public. It’s the things), but not to the point that the reader
break it. We built devices that held laptops pre- same if you’re writing about technology or providing thinks about YOU rather than the product.
cariously over various surfaces and dropped them the supporting documents that ship with the prod-
repeatedly from a specific and controlled height. uct. You can use (or reread) your work again and A good tester or editor will know what you meant
We wired keyboards and spilled various substances again, but you still know what the original intention and be able to help you produce the result that
(soda, water, coffee, etc.) on them until they failed, was, and logical lapses won’t jump out at you the you had in mind. You might even be a pretty
and measured how much electricity zapped the key- way they would to someone who’s not using your good tester or editor yourself. But there’s a dan-
board and whether it went with a whimper or a bang. brain. You need someone to intentionally break your ger in thinking that you can be your own tester
We did the opposite of what every well-intentioned product and then give you feedback. or editor. You know that old adage, “The lawyer
instruction told us to do. We had a Faraday Cage to who represents himself has a fool for a client,”
deliberately electrocute computers and a completely What if your first user (or editor) has different taste right?
soundproof room where we could measure how loud or disagrees with your design? What if they don’t
that fan keeping your hard drive cool really was or understand your goal, or worse, what if they inject A good dev or writer can certainly make a decent
how much noise a room full of mainframes made. In their own ideas into your work? That’s the second pass at his own work, tweaking here and tidy-
short, we had a whole lot of fun. half of having your work tested or edited. As impor- ing there. And that should happen, every time,
tant as it is to get feedback, it’s just as important to whether you’re writing code or text. But it’s a
The object wasn’t really to have fun but to use the know how to respond to it. very bad idea to deliver a product that only you
product in the worst possible way in a controlled have tested or edited.
environment so that the various tragedies could be Let’s say that you build an app that measures hik-
measured. We barely read, entirely skipped, or ob- ing paths. You track whether the paths are also It’s the weird interpretations other people make
stinately misinterpreted instructions. We researched suitable for horses, bicycles, or small motor vehi- that allow those flashes of inspiration and insight
statistics—how many seated users knocked a laptop cles, you’ve got elevation change, and you track and make your work better. That’s how you grow.
off their laps or dropped one while running through distance and give a letter grade for difficulty. You’ll never be finished growing if you’re good at
an airport. We even had a rubber finger on a stick Your beta user wants a bigger picture—parking what you do.
that poked the same ke, around the clock for weeks availability, running and hiking clubs that use
on end until the key broke. the park, handicapped access, bathroom and wa- Post Script: One of my editor friends suggested a
ter availability, and so forth. Dr. Dobb’s Journal frequent blogger’s posts about
We studied whether a non-technical person could testing. The Dr. Dobb’s site went dark in 2014,
figure out how to use a piece of software. To per- Those are good ideas, of course, but perhaps that’s but the articles, and many new ones by Michael
form such a test, I built a database using FoxPro not the app you’re building. Or perhaps those are on Hunter, are available here: http://www.thebraidy
that tracked the timecards and contract lengths the wish list (backlog) for V2, but you’ve got a dead- tester.com/. I’ve got more than a hundred articles
for ZD Labs’ team of freelancers. I enjoyed it line to meet. It’s your job to figure out whether the on writing for technical people on my website, at
enough that I next volunteered to build a much app’s users need those things or whether they’re www.MelanieSpiller.com.
more involved database using an Oracle product just bells and whistles. You might have to do a cost
(with a lot of help) to set up a software and lit- analysis to make this decision or maybe you already Melanie Spiller
erature library at the lab. know the right thing to do.
66
Editorial codemag.com

ONLINE QUICK ID 1703021
Data-Driven Testing with Visual Studio
Every developer needs to test their own code or have it tested by someone else. Many developers aren’t great at testing their
own work. The main reason is that we tend to test only the “happy path” through the functionality that we wrote. We often
avoid testing the boundaries of our code, such as invalid inputs, exceptions that might occur, etc. One way to become a better
tester is to start writing unit tests. Although it takes You also save the time that you normally eat up when you
more time up-front to write unit tests, it saves a ton of do your own testing by pressing F5 to start debugging in
time if you have to regress test changes to existing fea- Visual Studio, waiting for the compile process, and click-
tures. ing through a half dozen menus to finally get to the point
where you want to start testing. As you know, this can
Starting with Visual Studio 2008, Microsoft added a sometimes take 15 seconds to a minute, depending on
unit testing framework into Visual Studio. One of the how large your application is. By unit testing instead,
great features of the unit testing tools in Visual Stu- you can run many tests in just a couple of seconds. This
dio is the ability to use a data-driven approach. There adds up to saving many hours over your complete devel-
Paul D. Sheriff are also several third-party testing frameworks you can opment cycle.
http://www.pdsa.com use. In this article, you’ll to learn to retrieve values
to be used for testing from SQL Server. Using a data- Automated tests are repeatable, unlike tests run by hu-
Paul D. Sheriff is the President of driven approach can significantly reduce the unit tests mans who might forget to test something. You end up
PDSA, Inc. PDSA develops custom you must write. with more of your code tested because things won’t be
business applications specializing
forgotten. Because you’re forced to think of how to test
in Web and mobile technolo-
your code while you’re writing it, you write better code.
gies. PDSA, founded in 1991, has Why You Should Test Your Code
You also save time on the set-up and the tear down of
successfully delivered advanced
We all know that we need to test code prior to putting it the tests because these tasks can also be automated. As
custom application software to
into production. Testing ensures that the code you write you can see, there are many advantages to an automated
a wide range of customers and
works as expected. It’s not enough to check that it works approach over human testing.
diverse industries. With a team of
as expected, but you must also check it under varying cir-
dedicated experts, PDSA delivers
cumstances and with different inputs. For example, what Of course, there are disadvantages to the automated ap-
cost-effective solutions, on-time
and on-budget, using innovative if someone takes the database offline? Will your code proach as well. First, it does take more time up-front to
tools and processes to better recover gracefully from this exception? Does your code develop these tests. Automated tests are only as good as
manage today’s complex and inform the user that there’s a problem with the database the person who develops the tests. The tools to test user
competitive environment. connection in a friendly and easily understood manner? interfaces are not always great, and they require that you
Paul is also a Pluralsight author. All of these questions need to be answered in the testing purchase third-party testing tools. Then again, if you’re
Check out his videos at of your code. You need to simulate these conditions so using good n-tier techniques, MVC, MVP, MVVM, or similar
http://www.pluralsight.com/ you can test your exception code. design patterns, there should be very little UI for you to
author/paul-sheriff. test anyway.
Performing the act of testing often helps you improve
the quality of your code. As you think about the various
The FileExists Method
scenarios that can go wrong, you start to add additional
code to handle these scenarios. This leads to your code For this article, you’re going to build a method that
being more robust and ultimately more maintainable and checks to see whether a file exists. You’re then going to
user-friendly. You’ll find that taking time to test your build unit tests to check each type of input that you can
code will make you a better programmer in the long run. pass to this method. Next, you’re going to replace all of
Your boss and your end-users will appreciate the extra those unit tests with a single unit test that retrieves the
effort as well. various inputs from a database table.
To start, create a new Class Library project in Visual
Automated Testing
Studio using C#. Set the name of this class library
Instead of you or a QA person doing all the testing, try to project to MyClasses. Rename the Class1.cs file created
automate as much as possible, called unit testing. Unit by Visual Studio to FileProcess. Add a method in this
testing means that you write a program, or more likely, a class called FileExists, as shown in the following code
series of programs, to test each line of code and ensure snippet:
that it operates properly under all circumstances. Unit
testing has become very prevalent in today’s professional public bool FileExists(string fileName) {
software shops. if (string.IsNullOrEmpty(fileName)) {
throw new ArgumentNullException("fileName");
Although this sounds like a lot of work, and it is more }
work up front, you’ll more than make up that time by
avoiding multiple regression tests that have to be done return File.Exists(fileName);
by a human. You can even automate the set-up and tear- }
down of databases, files, etc. With the correct architec-
ture, you can automate almost all of the various inputs a This is a very simple method, yet it requires at least three
human tester would have to enter by hand. unit test methods to ensure that this method works with
8
Data-Driven Testing with Visual Studio codemag.com
all possible inputs. The three possible values you can in a null value or a blank value to the FileExists method.
pass to the fileName parameter are: An ArgumentNullException is thrown from the FileExists
method if a null or blank value is passed to the method.
• A file name that exists There are two ways to handle this thrown exception.
• A file name that does not exist First, add an ExpectedException attribute after the Test-
• A null or empty string Method attribute on the method, as shown in the follow-
ing code snippet.
Create a Test Project
[TestMethod]
Right-mouse click on your MyClasses solution and choose [ExpectedException(typeof(ArgumentNullException))]
Add -> New Project. From the list of templates, click on public void FileExistsTestNullWithAttribute() {
the Visual C# -> Test -> Unit Test Project. Set the Name FileProcess fp = new FileProcess();
to MyClassesTest. Click the OK button. Rename the Unit-
Test1.cs file to FileProcessTest.cs. You’re going to test fp.FileExists("");
the method in your MyClasses class library, so you need }
to add a reference to that project. Right-mouse click on
the References folder in the MyClassesTest project and The second way to handle this exception is to wrap up the
select MyClasses. Add the following using statement at call to the FileExists method within a try…catch block.
the top of the FileProcessTest.cs file. The catch block should check to see if the exception is
an ArgumentNullException. If it is, don’t do anything to
using MyClasses; tell the unit test framework that this test succeeded. If
no exception is thrown, there’s something wrong with
It’s now time to start writing the unit tests to create each the logic and you should call the Assert.Fail() method
of the three possible inputs identified for this method. to signal to the unit test framework that this test failed.
The first one is to test that a file exists. Add the code Let’s use this second method because this is what you’ll
shown below to the FileProcessTest class. Feel free to do when you go to a data-driven approach.
change the drive letter, path, and file name to a file that
exists on your computer.
[TestMethod]
public void FileExistsTestTrue() {
FileProcess fp = new FileProcess();
bool fromCall;
fromCall =
fp.FileExists(@"C:\Windows\Regedit.exe");
Assert.AreEqual(true, fromCall);
}
After adding this code, right-mouse click in your code
window and choose Run Tests from the context-sensitive
menu that appears. After the code runs, a Test Explorer
window appears with the results of the test. If the file
exists, the window should display something that looks
like Figure 1.
The next method to write tests for a file that doesn’t ex-
ist. Create a method in your FileProcessTest class to test
this condition. Write the code shown in the following
code snippet.
[TestMethod]
public void FileExistsTestFalse() {
FileProcess fp = new FileProcess();
bool fromCall;
fromCall =
fp.FileExists(@"C:\BadFileName.txt");
Assert.AreEqual(false, fromCall);
}
Once again, run these tests and you should now see two
passed tests in your Test Explorer window. Add the fi-
nal test to the FileProcessTest class to test if you pass Figure 1: Test results appear in the Test Explorer window.
9
codemag.com Data-Driven Testing with Visual Studio
[TestMethod] 4. Add a DataSource attribute to your test method.
public void FileExistsTestNull() { 5. Add a config file to hold a connection string and
FileProcess fp = new FileProcess(); table name to use.
try { Create a Table to Hold Test Data
fp.FileExists(""); Because you created three test methods, you’re going to
Assert.Fail(); need a table with three rows, one for each test. Each test
} passes one value, and returns a Boolean value, so the
catch (ArgumentNullException) { table needs at least two fields: FileName and ReturnVal-
// The test succeeded ue. Add one more column named CausesException that
} you can set to a true or false value on whether you are
} expecting an exception to be thrown by the method you
are testing. Create this table in a database with the script
Run the unit tests one more time, and you should now shown in Listing 1.
see three passed tests in the Test Explorer window. Us-
ing this approach to testing means that you need to cre- The data in this table that was created from the script
ate different methods for each individual file and return matches the hard-coded values in the three-unit test
value combination that you wish to test. Extrapolate methods. Table 1 shows the values that are now in your
this to a method that has several parameters, multiple table. Feel free to use any specific file names and return
If statements or Switch statements, and you can see how values that make sense for your computer.
the number of methods you must write can grow substan-
tially. This is where a data-driven approach to passing Add Properties and References
parameters to your methods reduces the amount of test When the unit test framework creates an instance of a
methods you need to create. test class (a class marked with a [TestClases] attribute),
it creates a TestContext object. This object contains
properties and methods related to testing. One of the
Create a Data-Driven Test
properties stores the data source information to allow
Now that you have a table, let’s create a test method you to access each row in the table you specify for the
that can be fed data from the FileProcessTest table you test. To access this TestContext object, you must cre-
created previously. There are a few steps to get the data- ate a property named TestContext in each of your test
driven test working. classes.
1. Create a table to hold parameter data. private TestContext _TestInstance;
2. Add a reference to System.Data to your test project. public TestContext TestContext
3. Add a TestContext property to your test class. {
get { return _TestInstance; }
set { _TestInstance = value; }
Listing 1: Create a table to hold test values }
CREATE SCHEMA tests
A DataTable is created from the table you create and a
GO
DataRow property is exposed on your TestContext prop-
erty. In order to use this property, you must add a refer-
CREATE TABLE tests.FileProcessTest
ence to the System.Data.dll. Go ahead and right-mouse
(
click on your test project’s References folder and select
FileName varchar(255) NULL,
Add Reference… from the menu. Then select Assemblies
ExpectedValue [bit] NOT NULL,
-> Framework, locate the System.Data assembly, and
CausesException [bit] NOT NULL
) add it to your project.
GO
Create Data-Driven Test Method
INSERT INTO tests.FileProcessTest Add a new method to your FileProcessTest class that looks
VALUES ('D:\Exists.txt', 1, 0); like the following code snippet. Don’t split the connec-
tion string across multiple lines, though; I had to format
INSERT INTO tests.FileProcessTest it to fit within the column width of this article. You also
VALUES ('D:\NotExists.txt', 0, 0); need to modify the name of your server and the database
in which you created the FileProcessTest table.
INSERT INTO tests.FileProcessTest
VALUES (null, 0, 1); [TestMethod()]
[DataSource("System.Data.SqlClient",
"Server=Localhost;
FileName ReturnValue CausesException Database=Sandbox;
Integrated Security=SSPI",
C:\Windows\Regedit.exe true false
"tests.FileProcessTest",
C:\NotExists.xls false false DataAccessMethod.Sequential)]
NULL false true public void FileExistsTestFromDB() {
Table 1: Data for the FileProcessTest table }
10
Data-Driven Testing with Visual Studio codemag.com