Thursday, October 18, 2007

Agitar Examples

I finally have a chance to post some examples of code generated by Agitar. I promised them in comments to the original post, but it turns out this is easier. First, I'll give a little background on the code that I wanted to test, and then I'll show the tests generated by Agitar. This example is designed to show the readability of Agitar. If a test fails after a change and its difficult to read, what approach should a developer take - read the test and see why it failed, or regenerate the test?

I wrote a simple interface for returning all the files under a directory:

(By the way I lost all my formatting and I apologize. Formatting on Blogger is a PITA.)

public interface ListFilesStrategy {
public List listFiles(File dir);

I have a two classes implementing this interface, RecursiveListFilesStrategy and NonRecursiveListFilesStrategy, which both extend AbstractListFilesStrategy.Here are the listings for AbstractListFilesStrategy and NonRecursiveListFilesStrategy:

public abstract class AbstractListFilesStrategy {

public void assertFileIsDirectory(File dir) {
if( dir == null )
throw new IllegalArgumentException("directory is null");

if( ! dir.isDirectory() )
throw new IllegalArgumentException("file is not directory");


public class NonRecursiveListFilesStrategy extends AbstractListFilesStrategy
implements ListFilesStrategy{

public List listFiles(File dir){

List files = new ArrayList();

List directories = new ArrayList();

while(! directories.isEmpty()){
File currentDir = directories.remove(0);
for( File f: currentDir.listFiles()){
if (f.isFile()) files.add(f);
else directories.add(f);
return files;

Now the test Agitar generated that was difficult to read. This test tested the listFiles method on my NonRecursiveListFilesStrategy:

public void testListFilesWithAggressiveMocks1() throws Throwable {
NonRecursiveListFilesStrategy nonRecursiveListFilesStrategy = new NonRecursiveListFilesStrategy();
File file = (File) Mockingbird.getProxyObject(File.class);
File file2 = (File) Mockingbird.getProxyObject(File.class);
File[] files = new File[0];
File file3 = (File) Mockingbird.getProxyObject(File.class);
File[] files2 = new File[2];
File file4 = (File) Mockingbird.getProxyObject(File.class);
File file5 = (File) Mockingbird.getProxyObject(File.class);
files2[0] = file4;
files2[1] = file5;
Boolean boolean2 = Boolean.TRUE;
Mockingbird.setReturnValue(false, file, "isDirectory", "()boolean", new Object[] {}, boolean2, 1);
ArrayList arrayList = (ArrayList) Mockingbird.getProxyObject(ArrayList.class);
Mockingbird.replaceObjectForRecording(ArrayList.class, "()", arrayList);
ArrayList arrayList2 = (ArrayList) Mockingbird.getProxyObject(ArrayList.class);
Mockingbird.replaceObjectForRecording(ArrayList.class, "()", arrayList2);
Boolean boolean3 = Boolean.FALSE;
Mockingbird.setReturnValue(false, arrayList2, "add", "(java.lang.Object)boolean", new Object[] {file}, boolean3, 1);
Mockingbird.setReturnValue(arrayList2.isEmpty(), false);
Mockingbird.setReturnValue(arrayList2.remove(0), file2);
Mockingbird.setReturnValue(false, file2, "listFiles", "()[]", new Object[] {}, files, 1);
Mockingbird.setReturnValue(arrayList2.isEmpty(), false);
Mockingbird.setReturnValue(arrayList2.remove(0), file3);
Mockingbird.setReturnValue(false, file3, "listFiles", "()[]", new Object[] {}, files2, 1);
Mockingbird.setReturnValue(false, file4, "isFile", "()boolean", boolean2, 1);
Mockingbird.setReturnValue(false, arrayList, "add", "(java.lang.Object)boolean", boolean3, 1);
Mockingbird.setReturnValue(false, file5, "isFile", "()boolean", boolean3, 1);
Mockingbird.setReturnValue(false, arrayList2, "add", "(java.lang.Object)boolean", boolean3, 1);
Mockingbird.setReturnValue(arrayList2.isEmpty(), true);
List result = nonRecursiveListFilesStrategy.listFiles(file);
assertNotNull("result", result);

This is certainly difficult to read. I'm pretty sure I could explain what its doing, but I'm more well read in testing and mocks than most developers. There are a few things they could do to clean it up however. They could try to be more in line with Behavior Driven Development and they have a few options in doing so. The method doesn't have an intent revealing name, I know what method its testing, but I don't know exactly what its doing. They could put in "given, when, then comments". The could use the extract method refactoring to seperate out the setup, the action, and the assertions, but maybe at least the setup portion.

All these things could be done, but even so there is a lot of setup happening here, and Most developers aren't ready, or aren't willing to read through it, and will likely start to ignore Agitar errors.

Now, I was told by Barry at Agitar that I could put in a test helper class, which would basically provide the setup portion of the test, and then it would generate more meaningful results. Here is an example:

public class FileTestHelper implements ScopedTestHelper {

public static File createFile() {
return new File("./src/main");

Should result in something like this …

public void testListFiles() throws Throwable {
ArrayList result = (ArrayList) new NonRecursiveListFilesStrategy().listFiles(FileTestHelper.createFile());
assertEquals("result.size()", 5, result.size());

Indeed, I could do something like this. But, there is a big problem with this. We have 5000+ classes that we want to generate tests for! How do we know which tests are meaningful, which ones need test helpers, yada yada?

I do promise more examples of simple methods that don't seem to be giving meaninful results. Mostly just checking to make sure methods catch NullPointerException. I do think the product will work wonderfully for green development, but will likely be ignored during legacy developement. Please let me know your thoughts.

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