1. 5/9/2018
Advanced Unit Testing
David Rabinowitz

2. Object Oriented Design Course
5/9/2018
Test Coverage
Tests are imperative for developing
How to write tests
How to know we have all important code covered?
What are possible risks
5/9/2018
Object Oriented Design Course

3. Object Oriented Design Course
5/9/2018
What to test
Correct results
Cross checking
Error conditions
Boundaries
Performance
5/9/2018
Object Oriented Design Course

4. Code coverage checking
5/9/2018
Code coverage checking
How do we know that we have our critical code covered
Statement coverage
Branch coverage
Path coverage
How to make sure it will be done automatically
5/9/2018
Object Oriented Design Course

5. Object Oriented Design Course
5/9/2018
Example
public int foo(int x, boolean b1, boolean b2) {
if (b1) {
x++; }
if (b2) {
x = -x;
return x;
5/9/2018
Object Oriented Design Course

6. Object Oriented Design Course
5/9/2018
Tests
Statement Coverage
testTT() {int x=foo(0,true,true); ...}
Branch Coverage
testFF() {int x=foo(0,false,flase); ...}
Path Coverage
testTT(), testTF(), testFT(), testFF()
5/9/2018
Object Oriented Design Course

7. Object Oriented Design Course
5/9/2018
Test coverage tools
Monitor the tests
Create a report of executed lines
Examples
Cobertura
Clover
many many more...
5/9/2018
Object Oriented Design Course

8. Object Oriented Design Course
5/9/2018
How they work
Placing special markers in the code
A post processor changes the generated bytecode
The instrumented bytecode is put to a different directory
The tests are run on the instrumented code
5/9/2018
Object Oriented Design Course

9. Object Oriented Design Course
5/9/2018
Pitfalls
Having high test coverage can lead to the (false) idea that our code is safe
Tests may be covering 100% of the code, but not all the cases
5/9/2018
Object Oriented Design Course

10. Object Oriented Design Course
5/9/2018
Example 1
public class PathCoverage {
public String pathExample(boolean
condition){
String value = null;
if(condition){
value = " " + condition + " "; }
return value.trim();
Taken from
5/9/2018
Object Oriented Design Course

11. Object Oriented Design Course
5/9/2018
Example 1 Test
public class PathCoverageTest extends TestCase {
public final void testPathExample() {
PathCoverage pt = new PathCoverage();
String value = pt.pathExample(true);
assertEquals("should be true",
"true", value); }
5/9/2018
Object Oriented Design Course

12. Example 1 Coverage Report
5/9/2018
Example 1 Coverage Report
5/9/2018
Object Oriented Design Course

13. Object Oriented Design Course
5/9/2018
Example 2
public class AnotherBranchCoverage {
public void branchIt(int value){
if((value > 100) || (HiddenObject.doWork() == 0)){
this.dontDoIt();
}else{
this.doIt(); }
private void dontDoIt(){ ... }
private void doIt(){ ... }
5/9/2018
Object Oriented Design Course

14. Object Oriented Design Course
5/9/2018
Example 2
public class HiddenObject {
public static int doWork(){
//return 1;
throw new RuntimeException("surprise!"); }
5/9/2018
Object Oriented Design Course

15. Object Oriented Design Course
5/9/2018
Example 2 Test
public class AnotherBranchCoverageTest extends TestCase {
public final void testBranchIt() {
AnotherBranchCoverage abc =
new AnotherBranchCoverage();
abc.branchIt(101); }
5/9/2018
Object Oriented Design Course

16. Example 2 Coverage Report
5/9/2018
Example 2 Coverage Report
5/9/2018
Object Oriented Design Course

17. Object Oriented Design Course
5/9/2018
Summary
Test coverage is a mean to check out the quality of our tests
Line coverage
Branch coverage
Can be easily integrated to build scripts
It cannot be taken for granted
Results should be carefully examined
5/9/2018
Object Oriented Design Course