Allowances and Expectations in Java

Making Data Matrix 2d barcode in Java Allowances and Expectations
Allowances and Expectations
Paint Data Matrix ECC200 In Java
Using Barcode creator for Java Control to generate, create Data Matrix 2d barcode image in Java applications.
We introduced the concept of allowances in The Sniper Acquires Some State (page 144) jMock insists that all expectations are met during a test, but allowances may be matched or not The point of the distinction is to highlight what matters in a particular test Expectations describe the interactions that are essential to the protocol we re testing: if we send this message to the object, we expect to see it send this other message to this neighbor Allowances support the interaction we re testing We often use them as stubs to feed values into the object, to get the object into the right state for the behavior we want to test We also use them to ignore other interactions that aren t relevant
Bar Code Maker In Java
Using Barcode creator for Java Control to generate, create bar code image in Java applications.
Download at WoweBookCom
Recognizing Barcode In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
24
Data Matrix ECC200 Drawer In Visual C#
Using Barcode maker for VS .NET Control to generate, create DataMatrix image in .NET framework applications.
Test Flexibility
Create Data Matrix ECC200 In Visual Studio .NET
Using Barcode drawer for ASP.NET Control to generate, create ECC200 image in ASP.NET applications.
to the current test For example, in Repurposing sniperBidding() we have a test that includes:
Data Matrix ECC200 Printer In .NET Framework
Using Barcode generator for .NET Control to generate, create Data Matrix 2d barcode image in Visual Studio .NET applications.
ignoring(auction); allowing(sniperListener)sniperStateChanged(with(aSniperThatIs(BIDDING))); then(sniperStateis("bidding"));
Data Matrix Generator In Visual Basic .NET
Using Barcode creator for VS .NET Control to generate, create Data Matrix 2d barcode image in .NET applications.
The ignoring() clause says that, in this test, we don t care about messages sent to the auction; they will be covered in other tests The allowing() clause matches any call to sniperStateChanged() with a Sniper that is currently bidding, but doesn t insist that such a call happens In this test, we use the allowance to record what the Sniper has told us about its state The method aSniperThatIs() returns a Matcher that checks only the SniperState when given a SniperSnapshot In other tests we attach action clauses to allowances, so that the call will return a value or throw an exception For example, we might have an allowance that stubs the catalog to return a price that will be returned for use later in the test:
ECC200 Generator In Java
Using Barcode creation for Java Control to generate, create ECC200 image in Java applications.
allowing(catalog)getPriceForItem(item); will(returnValue(74));
Bar Code Creator In Java
Using Barcode creation for Java Control to generate, create barcode image in Java applications.
The distinction between allowances and expectations isn t rigid, but we ve found that this simple rule helps:
Barcode Generation In Java
Using Barcode creation for Java Control to generate, create barcode image in Java applications.
Allow Queries; Expect Commands
Code39 Drawer In Java
Using Barcode maker for Java Control to generate, create Code 39 Full ASCII image in Java applications.
Commands are calls that are likely to have side effects, to change the world outside the target object When we tell the auditTrail above to record a failure, we expect that to change the contents of some kind of log The state of the system will be different if we call the method a different number of times Queries don t change the world, so they can be called any number of times, including none In our example above, it doesn t make any difference to the system how many times we ask the catalog for a price
EAN13 Printer In Java
Using Barcode creation for Java Control to generate, create EAN13 image in Java applications.
The rule helps to decouple the test from the tested object If the implementation changes, for example to introduce caching or use a different algorithm, the test is still valid On the other hand, if we were writing a test for a cache, we would want to know exactly how often the query was made jMock supports more varied checking of how often a call is made than just allowing() and oneOf() The number of times a call is expected is de ned by the cardinality clause that starts the expectation In The AuctionSniper Bids, we saw the example:
ANSI/AIM I-2/5 Creator In Java
Using Barcode printer for Java Control to generate, create ANSI/AIM ITF 25 image in Java applications.
atLeast(1)of(sniperListener)sniperBidding();
Data Matrix Scanner In Visual Studio .NET
Using Barcode decoder for VS .NET Control to read, scan read, scan image in .NET applications.
Download at WoweBookCom
Barcode Generator In Visual Studio .NET
Using Barcode printer for .NET framework Control to generate, create barcode image in .NET framework applications.
Precise Expectations which says that we care that this call is made, but not how many times There are other clauses which allow ne-tuning of the number of times a call is expected, listed in Appendix A
Bar Code Printer In .NET
Using Barcode maker for ASP.NET Control to generate, create barcode image in ASP.NET applications.
Ignoring Irrelevant Objects
Bar Code Maker In VS .NET
Using Barcode generation for .NET Control to generate, create bar code image in VS .NET applications.
As you ve seen, we can simplify a test by ignoring collaborators that are not relevant to the functionality being exercised jMock will not check any calls to ignored objects This keeps the test simple and focused, so we can immediately see what s important and changes to one aspect of the code do not break unrelated tests As a convenience, jMock will provide zero results for ignored methods that return a value, depending on the return type:
Generate Code 39 Extended In VB.NET
Using Barcode maker for Visual Studio .NET Control to generate, create Code39 image in Visual Studio .NET applications.
Create Code 128 Code Set C In Visual Studio .NET
Using Barcode printer for ASP.NET Control to generate, create ANSI/AIM Code 128 image in ASP.NET applications.