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![Assert in JUnit!
assertEquals("failure - strings not same", 5l, 5l);
assertNotNull("should not be null", new Object());
int objA[] = new int[10];
int objB[] = new int[10];
assertArrayEquals(objA, objB);
https://github.com/junit-team/junit/wiki/Assertions](https://image.slidesharecdn.com/tdd-140120052130-phpapp02/85/Test-Driven-Development-Workshop-31-320.jpg)
Uploaded byAnjana Somathilake
Test Driven Development - Workshop
Test Driven Development (TDD) is a software development process that relies on the repetition of a very short development cycle: requirements are turned into very specific test cases that are failed, then the software is improved to pass the new tests, and finally any newly introduced code is refactored. The document outlines the TDD lifecycle and process, describes unit testing and how it verifies isolated units of code, and discusses how TDD results in testable, clean code through refactoring. It provides examples of unit testing code for a bank account class.
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Test Driven Development - Workshop
- 1. Test Driven Development(TDD) Workshop! ! Anjana Somathilake! Director, Engineering and Architecture at Leapset! ! Proprietary & Confidential
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- 4. Problem #1! In thebeginning, your source code was perfect!! Then it all changed…!
- 5. Problem #2! “Fix onething, break another!”!
- 6. Problem #3! You knowhow to build it, ! but you don’t know how to prove that it works!!
- 7. Problem #4! What ifI change this piece of code?!
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- 9. Problem #6! Developers getto know about the issues only after the QA testing.!
- 10. Types of Testing ! • • • • • • • • • • • • • • Unittesting! Installation testing! Compatibility testing! Smoke and sanity testing! Regression testing! Acceptance testing! Functional testing! Destructive testing! Performance testing! Usability testing! Accessibility testing! Security testing! Integration testing! A/B testing!
- 11. Scope! • Introduction toTDD! • Unit Testing! ! • Refactoring!
- 12. Introduction to TestDriven Development !
- 13. TDD as aHabit! “TDD is NOT an expert level practice, it is rather simple habit of writing the test first!”!
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- 15. What TDD isall about?! Testing?! Design!
- 17. TDD Lifecycle ! Write a failingtest Refactor Write the code to make this test pass
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- 19. TDD Lifecycle -Detailed ! Add a Test – Each new feature begins with writing a test. This test must initially fail since it is written before the feature has been coded.! ! Run All Tests – validate that the test-harnesses work and that the new test does not mistakenly pass without requiring any new code.! ! Write Development Code – That will cause the test to pass.! ! Run Tests – If all test cases pass the code meets all the tested requirements.! ! Clean Up Code – Refactor code to make production ready removing any dummy/stub code.! ! Repeat Process – Starting with another new test, the cycle is then repeated to push forward the functionality.!
- 20. TDD Results! • Testable Code • WorkingSoftware • Enforce Thinking Ahead • Clean & Maintainable Code • Increment Code Quality • Faster Feedback • Bring Back the Joy of Coding
- 21. TDD in anutshell! 1. Write a test! 2. Watch the test fail! 3. Write just enough code ! 4. Pass the test! 5. Refactor, remove duplications! 6. Pass the test again!
- 22. TDD in extremelysimplified ! • Write a failing test! • Pass the test! • Repeat!
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- 24. Unit Testing –Software Equivalent of Exercising !
- 25. Unit Testing ! A unittest is a piece of code that invokes a unit of work in the system and then checks a single assumption about the behavior of that unit of work.!
- 26. Unit of Work ! • A unit of work is a single logical functional use case in the system that can be invoked by some public interface (in most cases)! • A unit of work can span a single method, a whole class or multiple classes working together to achieve one single logical purpose that can be verified!
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- 29. Assertions! A confident andforceful statement of fact or belief.! ! “I assert that the earth is round”! ! But if the assertion is wrong, then there is something fundamentally flawed about the understanding.! ! This is the fundamental principle used in unit testing.!
- 30. Assertions in coding! • At this point in my code, I assert these two strings are equal! ! • At this point in my code, I assert this object is not null!
- 31. Assert in JUnit! assertEquals("failure- strings not same", 5l, 5l); assertNotNull("should not be null", new Object()); int objA[] = new int[10]; int objB[] = new int[10]; assertArrayEquals(objA, objB); https://github.com/junit-team/junit/wiki/Assertions
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- 33. Bank Account! Sprint 1! ! • • • • Createa bank account! Deposit 100! Withdraw 50! Check the balance! ! ! Sprint 2 ! • Max withdrawal is 5000! • Add penalty of 5, if withdraw more than the balance! ! ! Sprint 3 • Throw an exception if negative value is passed to the deposit method
- 34. Unit Test Structure! Arrange Act Assert @Test publicvoid deposit500(){ BankAccount bankAcct = new BankAccount(); bankAcct.deposit(500); assertEquals(500, bankAcct.getBalance()); }
- 35. Unit Test CodeCoverage! How much unit testing is enough?! ! How to measure the coverage?! ! Is there a tool for this?!
- 36. Unit Test CodeCoverage!
- 37. Benefits of UnitTests ! • Fast! • Easy to write and maintain! • Better code coverage! • When fail, provide insight into the problem!
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- 39. Refactoring! Refactoring is theprocess of clarifying and simplifying the design of existing code, without changing its behavior.! ! ! At the smallest scale, a “refactoring” is a minimal, safe transformation of your code that keeps its behavior unchanged.!
- 40. Most well-known RefactoringPatterns.!
- 41. Inline Temporary Variable ! Replaceall uses of a local variable by inserting copies of its assigned value.! public double applyDiscount() { double basePrice = _cart.totalPrice(); return basePrice * discount(); } public double applyDiscount() { return _cart.totalPrice() * discount(); }
- 42. Extract method! Create anew method by extracting a code fragment from an existing! method.! public void report(Writer out, List<Machine> machines) throws IOException { for (Machine machine : machines) { out.write(“Machine “ + machine.name()); if (machine.bin() != null) out.write(“ bin=” + machine.bin()); out.write(“n”); } } public void report(Writer out, List<Machine> machines) throws IOException { for (Machine machine : machines) { reportMachine(out, machine); } } private void reportMachine(Writer out, Machine machine) throws IOException { out.write(“Machine “ + machine.name()); if (machine.bin() != null){ out.write(“ bin=” + machine.bin()); } out.write(“n”); }
- 43. String Calculator Exercise! 1. Create a simple String calculator with a method int Add(string numbers)! 1. The method can take 0, 1 or 2 numbers, and will return their sum (for an empty string it will return 0) for example “” or “1” or “1,2”! 2. Start with the simplest test case of an empty string and move to 1 and two numbers! 3. Remember to solve things as simply as possible so that you force yourself to write tests you did not think about! 4. Remember to refactor after each passing test! 2. Allow the Add method to handle an unknown amount of numbers! ! 3. Calling Add with a negative number will throw an exception “negatives not allowed”!
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