1. EEC-492/693/793 iPhone Application Development
Lecture 19
Wenbing Zhao & Nigamanth Sridhar
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EEC492/693/793 - iPhone Application Development

2. EEC492/693/793 - iPhone Application Development
Outline
Unit Testing
Objective-C runtime
Demos
Assignment:
Build the temperature converter app with unit testing
Build the RuntimeFun app
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EEC492/693/793 - iPhone Application Development

3. EEC492/693/793 - iPhone Application Development
What Are Unit Tests?
Test specific areas of functionality
Minimal external dependencies
Run frequently during development
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EEC492/693/793 - iPhone Application Development

4. EEC492/693/793 - iPhone Application Development
Who Writes Unit Tests?
You (developers) do!
Ideally written along with new code
Test-driven development
Write tests first
Fill in the implementation until tests pass
Repeat for any new changes
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EEC492/693/793 - iPhone Application Development

5. EEC492/693/793 - iPhone Application Development
Running Unit Tests
Automate so you don't have to explicitly run tests
Many testing frameworks can run tests every time you build
Just as compiler checks syntax, unit tests check semantics
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EEC492/693/793 - iPhone Application Development

6. EEC492/693/793 - iPhone Application Development
Why Unit Tests?
Fewer bugs
More confidence that you're shipping a high quality product
Find bugs early
Bugs are easier (and cheaper) to fix early in development
Avoid regressions
Ensure that changing one piece of code doesn't break another
Document your code
How is a method intended to be used? Check out the tests...
Encourage good design
Spaghetti code is hard to test! Design with testability in mind
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EEC492/693/793 - iPhone Application Development

7. Unit Testing Frameworks
OCUnit for Objective C
Ships with Mac OS X developer tools, integrates with Xcode
Included with iPhone SDK as of 2.2
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EEC492/693/793 - iPhone Application Development

8. EEC492/693/793 - iPhone Application Development
Basics of OCUnit
SenTestCase is abstract test case superclass
Automatically runs methods that begin with “test”
Macros for asserting conditions during tests
STAssertEquals(value_1, value_2, failure_description, ...)
STAssertNotNil(object, message, ...)
STAssertTrue(expression, message, ...)
STAssertFalse(expression, message, ...)
STAssertThrowsSpecific(expression, exception, message, ...)
STAssertNoThrow(expression, message, ...)
-setUp and -tearDown methods run before and after each test
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9. Adding OCUnit to an Xcode Project
1. Launch the first project
2. Create a new target to run the tests
Choose "Project > New Target" and select the “Cocaa Touch->Unit Test Bundle" target type. After clicking the "Next" button, name the new target "Test" Click the "Finish" button
Right-click the “Test” target, add the original project target as direct dependent (by clicking on the + sign and select the target)
3. Add the OCUnit framework
Right-click Frameworks folder and choose “Add > Existing Frameworks” Select the /Developer/Library/Frameworks/SenTestingKit.framework, then click the Add button
Right-click SenTestingKit.framework and choose “Get Info”, check the “Test” target, and uncheck the original project test
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EEC492/693/793 - iPhone Application Development

10. Adding OCUnit to an Xcode Project
4. Create a new group for the test cases
Add a new group “Test Cases”
5. Creating a test case
Right-click on the “Test Cases” group, select “Add > New File”
Select “Cocoa Touch class > Objective-C test case class”, then click “next” button
Name the test case in the following dialog
Make sure to uncheck the “Test” target and uncheck the original project target before you click “Finish” button
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EEC492/693/793 - iPhone Application Development

11. Adding OCUnit to an Xcode Project
6. Unless you want to do application-level unit testing, remove all #if #else for USE_APPLICATION_UNIT_TEST in the generated source code for the unit test
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12. Defining A New Test Case Class
#import <SenTestingKit/SenTestingKit.h>
@class Foo;
@interface FooTests : SenTestCase {
Foo *foo; }
@end
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EEC492/693/793 - iPhone Application Development

13. EEC492/693/793 - iPhone Application Development
Preparing Tests
@implementation FooTests
- (void)setUp {
// Every test will have its own Foo instance
foo = [[Foo alloc] init]; }
- (void)tearDown {
[foo release];
...
@end
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EEC492/693/793 - iPhone Application Development

14. EEC492/693/793 - iPhone Application Development
Adding Tests
@implementation FooTests
...
- (void)testCreateFoo {
create Foo"); }
- (void)testSetBar {
Bar *bar = ...;
foo.bar = bar;
STAssertEqualObjects(foo.bar, set foo.bar");
@end
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EEC492/693/793 - iPhone Application Development

15. Testing Error Conditions
@implementation FooTests
...
- (void)testOutOfBoundsAccess {
STAssertNil([foo 99 should be nil"); }
@end
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EEC492/693/793 - iPhone Application Development

16. Unit Testing Philosophy
Keep tests short, lightweight, fast
Test individual methods, not end-to-end behavior
Find a new bug? Write a new test before you fix it
The benefit could still be huge even if only a subset of behavior can be unit-tested
Networking
Databases
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EEC492/693/793 - iPhone Application Development

17. EEC492/693/793 - iPhone Application Development
Objective-C Runtime
How does OCUnit find all the methods that begin with “test”?
Any other cool tricks?
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EEC492/693/793 - iPhone Application Development

18. EEC492/693/793 - iPhone Application Development
/usr/include/objc
<objc/objc.h>
id, Nil, nil, BOOL, YES, NO
<objc/message.h>
objc_msgSend() and friends
<objc/runtime.h>
Inspect and manipulate classes, protocols, methods
Add and replace methods at runtime
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EEC492/693/793 - iPhone Application Development

19. Inspecting Methods & Properties
Copy all methods for a classj
// get instance methods
Method *class_copyMethodList( Class cls, unsigned int *outCount);
// get class methods, use:
class_copyMethodList(object_getClass(cls), &count).
Get attributes for a method
SEL method_getName(Method m);
IMP method_getImplementation(Method m);
char *method_copyReturnType(Method m);
...
Get properties for a class
objc_property_t *properties = class_copyPropertyList(Class cls,
unsigned int *outCount);
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EEC492/693/793 - iPhone Application Development