Designing High Quality Apps using Test-Driven ... - ASUG.com

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Designing High Quality Apps using Test-Driven Development with ABAP Objects. JK (JayaKumar Pedapudi) - Principal Consultant - NTT DATA, Inc.

[ Agenda  Introduction  Agile Programming Strategy    

Learning Points Return on Investment (ROI) About Test Driven Development (TDD) TDD Mantra & TDD Basics

 Simple TDD – Demo  3 Laws of TDD

 The Unit-Testing Framework  ABAP Unit – A Design Methodology  Myths on Unit Testing & Best Practices  Wrap Up, Take Away Points & Q&A

 Appendix Real Experience. Real Advantage.

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[ About NTT DATA, Inc. - NTT DATA Americas Integration Americas – 17,000 employees and $1.3B in revenues – Offering clients more options through increased depth and scale across: • Consulting & Systems Integration • Applications Services / ERP • Infrastructure Services • BPO Services • BI, Analytics & Performance Mgmt • Strategic Staffing – Balanced Industry depth in healthcare, commercial, financial and public sector

– Successful long-term relationships with rich and diverse customer base

Onshore

– Balanced global delivery model that maximizes consistency and cost efficiencies

Offshore

‘NTT DATA Your Innovation Partner, Anywhere around the world’ Real Experience. Real Advantage.

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[ Agile Programming Strategy  There is an urgent need for an agile programming strategy that can help customer/businesses with following benefits.  Reduce the software development costs  Improve software reliability  Decrease development time  Working application product

 Better Return On Investment

 “Test-driven development (TDD) is a software development strategy that requires that automated tests be written prior to writing functional code in small, rapid iterations.”

Real Experience. Real Advantage.

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[ Learning Points  Learn how TDD enables the writing of software that has better structure, in less time and with fewer defects.  Discover how TDD results in better code design, usability design, safety net, instant feedback, modularity and documentation.  Learn about the techniques and best practices to make it almost impossible to deliver bugs in the next software project.


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[ Return on Investment (ROI) No Feedback

Number of Bugs

Without TDD

Done ?

Time Development

Quality Assurance Integration & System Testing

Development

Quality Assurance

Traditional


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[ Return on Investment (ROI) Life Cycle Benefit - Investment ROI = Investment No Feedback

Number of Bugs

Without TDD

Done ? With TDD Done Sooner ! Continuous Feedback

Time

Development

Quality Assurance Integration & System Testing

Development

Quality Assurance

Traditional TDD

Development Investment

Life Cycle Benefit Net Return Real Experience. Real Advantage.

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[ Return on Investment (ROI) (cont’d)  Better Code Design

 Usable Code  Safety Net

 Modularity  Instant Feedback

 Increased Productivity  WYGIWYM (What You Get Is What You Meant)

 Documentation


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[ About TDD…  What is Test Driven Development (TDD)?  Test Driven Development (TDD) is a software development technique and one of the aspects of Extreme Programming (XP).  TDD is a design methodology.  TDD is NOT about testing.  TDD is a software development technique that uses short development iterations based on pre-written test cases that define desired improvements or new functions.  TDD is about design and development. The process of designing software by writing a validating test before the code.  TDD is a technique whereby you write your test cases before you write any implementation code.  These tests drive or dictate the code that is developed. Real Experience. Real Advantage.

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[ About TDD (cont’d)  Why TDD?  Better Code Design  Usable Code

 Safety Net  Modularity  Instant Feedback  Increased Productivity  WYGIWYM (What You Get Is What You Meant)  Documentation Real Experience. Real Advantage.

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[ About TDD (cont’d)  Why TDD? (Cont’d)  The test is the executable specification.  You start visualizing the goal first, design the API, then later think about the possible implementation.

 You develop just enough.  You get to the goal as quick as possible.

 You don’t develop unnecessary code.  There is no code without a test.  There is no test without a user requirement.


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[ About TDD (cont’d)  Why TDD? (Cont’d)  Once you get test working, you know it is working.  The test gives us the courage to refactor.  It’s more fun that way, it reduces fear and builds confidence.

“Regression testing = Stable software = Quality software”


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[ TDD Mantra The TDD Mantra…  Write a single Unit Test for a very small piece of functionality and then Compile/Check syntax/Run and see it fails (RED).  Write the simplest amount of code that will make the test compile and pass (GREEN).  REFACTOR the code and/or tests to improve the design and still pass (GREEN). Kent Beck writes in his book "Test-Driven Development: By Example” as Red/Green/Refactor – the TDD mantra. Real Experience. Real Advantage.

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[ TDD Basics How does TDD help?  TDD helps you produce clean working code that fulfills requirements.  Write Test Code  Code that fulfills requirements.

 Write Functional/Production Code  Working code that fulfills requirements.

 Refactor  Clean working code that fulfills requirements.

 Refactoring?  “A change to the system that leaves its behavior unchanged, but enhances some nonfunctional quality – simplicity, flexibility, understandability, performance” - (Kent Beck, Extreme Programming Explained). Real Experience. Real Advantage.

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[ TDD Basics (cont’d) Principle of TDD (In Practice) Start Write a Test Run the Test

Refactoring

Write (just enough) Production Code to compile Run the Test

Run the Test

Write (just enough) Production Code to pass


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[ TDD Basics (cont’d)  What it takes to adopt TDD?  Requires good knowledge on Object Oriented Concepts.  Requires minimum knowledge on ABAP Objects.  Requires minimum SAP NetWeaver 2004 version.  Prior version don’t have the Unit Testing Framework available.

 Requires Unit-Testing Framework  (Built into ABAP workbench from SAP NetWeaver 2004 onwards)

 Requires better coding techniques to write clean code.  Requires real commitment and discipline to follow this process, in order to get better quality results.


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[ Simple TDD – Demo  Simple tip calculation program.

(Consider standard 15 percent for easy calculation) Real Experience. Real Advantage.

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[ Simple TDD – Demo (cont’d)  Simple test for testing this tip calculation routine:


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[ Simple TDD – Demo (cont’d)  Executing ABAP Unit Test  Menu "Program->Test->Unit Test" or by pressing Ctrl+Shift+F10.

 It is important that the system is configured in such a way that it allows the ABAP Unit tests to be performed.  This means completing the configuration in transaction SAUNIT_CLIENT_SETUP, as well as setting the profile parameter abap/test_generation equal to ON.  This profile parameter should be defined by the SAP NetWeaver administrator for the system. Real Experience. Real Advantage.

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[ Simple TDD – Demo (cont’d)  Understanding ABAP Unit Result Display  ABAP Unit Test Overview (On the left hand side of the result display)

 The test overview section provides a simple overview of all of the tests that were executed and includes the aggregate status of each test.  It also displays the number of assertions and the assertion error level for each test. Real Experience. Real Advantage.

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[ Simple TDD – Demo (cont’d)  Understanding ABAP Unit Result Display (cont’d)  ABAP Unit Assertion Messages (On the top right hand side of the result display)

 The messages section provides a listing of all of the assertion messages that were logged during the test.  The message displayed here come from passing the failure text to the MSG parameter when calling one of the ASSERT methods.  By double-clicking on an entry, the detail of the assertion message is shown in the detail section of ABAP Unit result display.


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[ Simple TDD – Demo (cont’d)  Understanding ABAP Unit Result Display (cont’d)  ABAP Unit Message Detail (On the bottom right hand side of the result display)

 The message details section provides details for each assertion message.

 To see where exactly the failure occurred in our test, we need to click on the link (Line: 44) provided under Stack node.


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[ Simple TDD – Demo (cont’d)  Understanding ABAP Unit Result Display (cont’d)  Assertion failure location (Clicking on the Link, i.e. "Line: 44")

 Assertion failed, because we are expecting '45' but the resulted TEST_AMOUNT was 300, which is wrong.  This resulted value is calculated inside the form routine CALC_TIP_AMOUNT. Real Experience. Real Advantage.

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[ Simple TDD – Demo (cont’d)  Understanding ABAP Unit Result Display (cont’d)  Reviewing the CALC_TIP_AMOUNT form routine


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[ Simple TDD – Demo (cont’d)  Understanding ABAP Unit Result Display (cont’d)  Fixing the issue/error in CALC_TIP_AMOUNT form routine and activating it.

 Running again ABAP Unit test by pressing Ctrl+Shift+F10 will result in successful message.  ABAP Unit can help us detect the failures/errors easily and can be tracked down. With ABAP Unit tests in place and with a open mind to simple analysis will bring great value and confidence.  All developers will love to use once they understand its easiness and the value it brings to the code quality and project. Real Experience. Real Advantage.

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[ 3 Laws of TDD First Law

Write no production code unless to pass a failing test. Second Law

Write no more of a test than is sufficient to make it fail. Third Law

Write no more production code than is sufficient to pass a failing test.


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[ The Unit-Testing Framework  Unit testing frameworks are quite popular in the objectoriented programming world.  Frameworks like JUnit (for Java), SUnit (for Smalltalk), and Test::Unit (for Ruby) provide a rich set of functionality.

 Various code-driven testing frameworks are collectively know as xUnit. Unit tests are at the core of TDD.  Unit testing frameworks helps simplify the process of Unit testing and the goal is to make writing test as painless as possible.  As of SAP NetWeaver 2004, ABAP Unit is available as Unit testing framework, which takes the ideas of JUnit from Java environment and applies them to ABAP. Real Experience. Real Advantage.

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[ ABAP Unit – A Design Methodology  ABAP Unit is a test tool highly integrated directly in the ABAP runtime environment.  ABAP Unit can be used for executing module/unit tests – i.e. for checking the functions of code sections in a program.

 ABAP Units are implemented using the ABAP programming language.  Therefore, the advantage is that there is no need to learn any additional test scripting language.  ABAP Unit is standardized process to test and it can be put into a QA process and used for automatic and rigorous testing.


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[ ABAP Unit – A Design Methodology (cont’d) Advantages of ABAP Unit.  The tests are programmed in ABAP.  Additional test script language is not required.

 The tests are developed in the ABAP development environment.  Additional interface operation is not required.

 In the development phase, tests can be called directly within the editor.  The test execution can be automated.  Mass tests are enabled by integration into the Code Inspector tool.


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[ ABAP Unit – A Design Methodology (cont’d) ABAP Unit implementation.  Tests are developed in the form of test methods in test classes during or even before the actual program development.  Test classes are local classes of the ABAP program to be tested and are thus a part of that program, which also ensures that the version integrity is maintained after transports.  Developers incorporate tests and test conditions (fixtures) into their programs and they themselves executes these tests.  Since the implemented code is first tested by developers themselves the higher quality product can be expected.


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[ ABAP Unit – A Design Methodology (cont’d) ABAP Unit Test Organization.


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[ ABAP Unit – A Design Methodology (cont’d) Main Components of ABAP Unit  Test Class and Test Method looks like:


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[ ABAP Unit – A Design Methodology (cont’d) Main Components of ABAP Unit (cont’d)  Test Attributes.  Test attributes are management attributes of test classes, which are taken into account during test execution.

 The test attributes of local test classes are defined using pseudo comments in the CLASS statement immediately following the FOR TESTING addition.

 You can specify one pseudo comment per line in the program and note that they are Case-Sensitive.


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[ ABAP Unit – A Design Methodology (cont’d) Main Components of ABAP Unit (cont’d)  Test Fixtures.  Fixtures is a test configuration that is created before a test method is called and also ensures a unique test behavior.

 Fixtures consists of test data, test objects, resources, and connections. The complete set of these test objects is called the test fixture.  Fixtures are nothing more than private method defined in the test class, which are used to set up specific conditions for the test.  These method names are reserved and are triggered automatically by the ABAP runtime. Real Experience. Real Advantage.

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[ ABAP Unit – A Design Methodology (cont’d) Main Components of ABAP Unit (cont’d)  Test Fixtures (cont.)


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[ ABAP Unit – A Design Methodology (cont’d) Test Execution Sequence


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[ ABAP Unit – A Design Methodology (cont’d) ABAP Unit Load Concepts  When this developed production code and test code are moved to production environment, the compiler and the run time will just ignore all the test code.


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[ ABAP Unit – A Design Methodology (cont’d) Services of ABAP Unit  The complete listing of the public static methods of class CL_AUNIT_ASSERT


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[ Myths around Unit Testing  Myth #1 : Will it not double the development time if we write unit tests? - No. Writing unit tests is a investment towards time savings over the lifetime of the project.


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[ Myths around Unit Testing (cont’d)  Myth #2 : All my unit tests just get outdated over a time! - No. Unit tests are not parallel to your code like documentation. You will be driving your code with them.


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[ Myths around Unit Testing (cont’d)  Myth #3 : Won’t the client refuse to pay for it? - No. The client is paying for clean, correct code. Unit testing is the means to that end.


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[ Best Practices Always start with a test for better API design. Write no production code unless to pass a failing test. Write no more of a test than is sufficient to make it fail. Always write simplest possible solution to make test pass. Write no more production code than is sufficient to pass a failing test.  Before Refactoring, always run the ABAP Unit test to make sure all the tests are passed and is all working.  Run ABAP Unit test very often to make sure nothing broken in the process. Remember “Your tests should drive or dictate the code that is being developed”     


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[ Wrap Up  We now know what is TDD and how it helps in designing better API for producing quality applications.  TDD helps building application that has better structure, in less time with better code design and usability design.

 TDD process produces instant feedback, which acts as safety net when making changes.  The Unit tests helps in writing modularized code and also helps as a documentation.  Learnt about 3 Laws of TDD and TDD Mantra.  ABAP Unit – Unit testing framework &  Best Practices. Real Experience. Real Advantage.

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[ Take Away Points  ABAP Unit, A Unit Testing Framework is built into ABAP Workbench from SAP NetWeaver 2004 onwards.  ABAP Unit is a test tool highly integrated directly in the ABAP runtime environment.  ABAP Units are implemented using the ABAP programming lang.  The tests are programmed and developed in ABAP development environment.  In a production system the ABAP Unit tests are not part of the productive program load and hence no performance or security drawbacks.  TDD is a design methodology and helps you produce clean working code to build the quality product.  The TDD Mantra – Red, Green & Refactor. Real Experience. Real Advantage.

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[ Additional References  Test-Driven Development: By Example  Kent Beck, Addison-Wesley, 2003.

 Test-Driven Development: A Practical Guide  Dave Astels, Prentice-Hall, 2003.  Refactoring: Improving the Design of Existing Code  Martin Fowler, Addison-Wesley, 1999

 Test Driven Development with ABAP Objects (Upcoming)  JK (JayaKumar Pedapudi), SAPPRESS.

 https://wiki.sdn.sap.com/wiki/display/ABAP/ABAP+Unit  http://xprogramming.com/index.php Real Experience. Real Advantage.

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[ Questions? Presented By: JK ( JayaKumar Pedapudi )

Email: [email protected]

Further Info: Pat Gray – Director, Marketing Email: [email protected]

Visit Booth Number: 2509


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SESSION CODE: 0913

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[ Appendix:  ABAP Unit – A Design Methodology  Main Components of ABAP Unit  ABAP Unit Load Concepts  ASSERT_EQUALS - Method parameters details  Unit Test Flow Control in case of Failure


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[ Appendix:

ABAP Unit – A Design Methodology

Main Components of ABAP Unit  Test Classes.  Test classes are local classes in ABAP programs, with the exception of type groups and interface pools (i.e., executable programs, class pools, function groups, module pools, and subroutine pools).  These test classes are not generated in productive systems and therefore cannot be executed.  Hence it is safe and there is no performance issue caused due to the test classes in production system.

 As of SAP NetWeaver 7.0, test classes can be implemented using the global classes. These global classes are abstract and can only be used in local test classes. Real Experience. Real Advantage.

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[ Appendix:

ABAP Unit – A Design Methodology (cont’d)

Main Components of ABAP Unit (cont’d)  Test Methods.  Test methods are parameter less (i.e., do not have method signature) instance methods of test class, which are used to trigger an ABAP Unit test.  These test methods are defined using the FOR TESTING addition to the METHODS statement in the CLASS definition block.  Each test method corresponds to an ABAP Unit test, which is responsible to trigger some block of production code in object you are testing.  Test methods should be private, or protected if the methods are inherited. Real Experience. Real Advantage.

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[ Appendix:


ABAP Unit Load Concepts  Production Code and Test Code.  The definition of test classes divides a program into production code and test code. Test code (i.e., Test classes and their components) are not generated in production systems.  So you cannot access a test class from the production code.  On the other hand, test classes can access all addressable components of a program and other test classes.  In a production system the ABAP Unit tests are not part of the productive program load.  Hence there are no performance or security drawbacks.  Since the tests are maintained along with corresponding production code, the code transportation would be easier. Real Experience. Real Advantage.

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[ Appendix:


ASSERT_EQUALS - Method parameters details

 This static method ASSERT_EQUALS is used to ensures the equality of two data objects. Two data objects in comparison can be a string or any data type object or an internal table, etc.


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[ Appendix:


Unit Test Flow Control in case of Failure.


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[ Motivation  If you are planning to test after you’ve developed the system, you won’t have enough time for testing.  Write the tests before the actual code!

 If things get complicated, you might fear that “the system” doesn’t work. You loose the confidence.  Execute the tests and get positive feedback (everything still works) or  Get instance feedback to locate the point that does not / no longer work.

 If you don’t have tests for the code, you shouldn’t use it / release it / ship it.  This can’t happen if you write the test first (so you develop better test coverage). Real Experience. Real Advantage.

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[ Motivation (cont’d)  If you’re overwhelmed by the complexity, you get frustrated.  Start with the simplest thing and proceed in tiny steps!

 If you are planning to skip the regression test, because you don’t have time, then they are more chances that application may go useless.  Writing tests along with development, helps in performing regression tests.

 If performance is only considered towards the end of the project, then you won’t be able to just “add a little more performance” to the system.  Re-use unit tests for performance tests even during the development and don’t start with performance tests late in the project! Real Experience. Real Advantage.

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