Journaling and Commitment Control processing is a means of automatically grouping a number of database updates into a single transaction for the purpose of recovery: either all or none of the updates will take place on files. We have to first create the journal using crtjrn and the crtjrnrcv journal receiver add the file on journal receiver and then set the commitment control. In the Edit Function Options section. What are the values for controlling whether or not a program is run under commitment control? M Master — Program is run under commitment control, program is controlling program and contains commit points.

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This article was peer reviewed by Mark Brown and MarcTowler. In real life projects, code often does all kinds of things that make testing hard. If you use setTimeout, your test will have to wait. But did you know there is a solution? By using Sinon, we can make testing non-trivial code trivial! What Makes Sinon so Important and Useful? Put simply, Sinon allows you to replace the difficult parts of your tests with something that makes testing simple.

If something external affects a test, the test becomes much more complex and could fail randomly. If you want to test code making an Ajax call, how can you do that? You need to run a server and make sure it gives the exact response needed for your test.

And what if your code depends on time? What now? You could use a setTimeout in your test to wait one second, but that makes the test slow. Imagine if the interval was longer, for example five minutes. By using Sinon, we can take both of these issues plus many others , and eliminate the complexity.

How Does Sinon Work? Sinon helps eliminate complexity in tests by allowing you to easily create so called test-doubles. Test-doubles are, like the name suggests, replacements for pieces of code used in your tests.

Looking back at the Ajax example, instead of setting up a server, we would replace the Ajax call with a test-double. It may sound a bit weird, but the basic concept is simple. Because JavaScript is very dynamic, we can take any function and replace it with something else.

Test-doubles just take this idea a little bit further. With Sinon, we can replace any JavaScript function with a test-double, which can then be configured to do a variety of things to make testing complex things simple. Sinon splits test-doubles into three types: Spies , which offer information about function calls, without affecting their behavior Stubs , which are like spies, but completely replace the function.

This makes it possible to make a stubbed function do whatever you like — throw an exception, return a specific value, etc Mocks , which make replacing whole objects easier by combining both spies and stubs In addition, Sinon also provides some other helpers, although these are outside the scope of this article: Fake timers , which can be used to travel forwards in time, for example triggering a setTimeout Fake XMLHttpRequest and server , which can be used to fake Ajax requests and responses With these features, Sinon allows you to solve all of the difficult problems external dependencies cause in your tests.

Installing Sinon First off we need to install Sinon. For Node. Getting Started Sinon has a lot of functionality, but much of it builds on top of itself. You learn about one part, and you already know about the next one. This makes Sinon easy to use once you learn the basics and know what each different part does. We usually need Sinon when our code calls a function which is giving us trouble. With time, the function might be setTimeout. With databases, it could be mongodb.

The function we are testing depends on the result of another function. We can say, the basic use pattern with Sinon is to replace the problematic dependency with a test-double.

When testing Ajax, we replace XMLHttpRequest with a test-double which pretends to make an Ajax request When testing time, we replace setTimeout with a pretend timer When testing database access, we could replace mongodb. Spies Spies are the simplest part of Sinon, and other functionality builds on top of them. The primary use for spies is to gather information about function calls. You can also use them to help verify things, such as whether a function was called or not.

In the example above, the firstCall property has information about the first call, such as firstCall. Although you can create anonymous spies as above by calling sinon. Without this your tests may misbehave. Spies have a lot of different properties, which provide different information on how they were used.

In practice, you might not use spies very often. In most testing situations with spies and stubs , you need some way of verifying the result of the test. We can use any kind of assertion to verify the results. Not fun. To fix the problem, we could include a custom error message into the assertion. This becomes very useful when you need to verify more complex condition, such as the parameters to a function.

Here are some examples of other useful assertions provided by Sinon: sinon. Stubs Stubs are the go-to test-double because of their flexibility and convenience.

They have all the functionality of spies, but instead of just spying on what a function does, a stub completely replaces it. This makes stubs perfect for a number of tasks, such as: Replacing Ajax or other external calls which make tests slow and difficult to write Triggering different code paths depending on function output Testing unusual conditions, for example what happens when an exception is thrown?

You should almost never have test-specific cases in your code. Instead of resorting to poor practices, we can use Sinon and replace the Ajax functionality with a stub. This makes testing it trivial. It takes an object as its parameter, and sends it via Ajax to a predefined URL. Here, we replace the Ajax function with a stub. This means the stub automatically calls the first function passed as a parameter to it. Only the behavior you need for the test is necessary, and anything else can be left out.

Another common usage for stubs is verifying a function was called with a specific set of arguments. For example, for our Ajax functionality, we want to ensure the correct values are being sent. We set up some variables to contain the expected data — the URL and the parameters. It also helps us set up the user variable without repeating the values. This time we used the sinon. We pass the stub as its first parameter, because this time we want to verify the stub was called with the correct parameters.

Mocks Mocks are a different approach to stubs. They are primarily useful if you need to stub more than one function from a single object. If you only need to replace a single function, a stub is easier to use. You should take care when using mocks! Unlike spies and stubs, mocks have assertions built-in. You define your expected results up front by telling the mock object what needs to happen, and then calling the verification function at the end of the test.

When using mocks, we define the expected calls and their results using a fluent calling style as seen above. This is the same as using assertions to verify test results, except we define them up-front, and to verify them, we call storeMock.

As in, the method mock. Each expectation, in addition to mock-specific functionality, supports the same functions as spies and stubs. Mocks should be used with care. Important Best Practice: Use sinon.

If you replace an existing function with a test-double, use sinon. In the earlier example, we used stub. This is necessary as otherwise the test-double remains in place, and could negatively affect other tests or cause errors.

But using the restore function directly is problematic. We have two ways to solve this: We can wrap the whole thing in a try catch block. This allows us to put the restore call in a finally block, ensuring it gets run no matter what. Or, a better approach, we can wrap the test function with sinon. The second thing of note is that we use this. Wrapping a test with sinon. Any test-doubles you create using sandboxing are cleaned up automatically.

Note that our example code above has no stub. If you use sinon. Sinon Is Not Magic Sinon does many things, and occasionally it might seem difficult to understand how it works.

This will help you use it more effectively in different situations. We can create spies, stubs and mocks manually too. This makes Sinon a lot more convenient. What about a Stub Then? Sinon is just much more convenient to use, than having to write your own library for the purpose. But with help from Sinon, testing virtually any kind of code becomes a breeze. Just remember the main principle: If a function makes your test difficult to write, try replacing it with a test-double.

This principle applies regardless of what the function does.


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