Sign in or 
| Version | User | Scope of changes |
|---|---|---|
| Apr 13 2009, 5:07 PM EDT (current) | jim.marion | 3637 words added, 8 photos added |
| Apr 13 2009, 3:02 PM EDT | jim.marion |
Changes
Key: Additions Deletions
An xUnit TDD Framework for PeopleSoft
Test Driven Development (TDD) is a software design technique that uses incremental, iterative unit tests to drive software design. TDD stipulates writing unit tests based on functional requirements, before coding units. As unit tests grow in number, organizing, running, and maintaining tests becomes difficult. Writing tests, without testing standards, further exacerbates this test maintenance issue.Testing frameworks help solve these maintenance problems by providing automation, organization, and testing standards. Many programming languages have testing frameworks that facilitate TDD, the xUnit testing frameworks being the most popular. Wikipedia maintains a list of Unit Testing Frameworks at http://en.wikipedia.org/wiki/List_of_unit_testing_frameworks.
Theoretically, we can drive PeopleCode development without a testing framework, but to follow TDD techniques, a framework certainly helps. With this document, I am pleased to introduce a unit testing framework for PeopleCode: PSUnit. PSUnit comes without warranty or support of any kind. PSUnit is nothing more than a collection of managed PeopleTools objects (pages, components, PeopleCode, etc) that facilitate testing and the development of test suites.
Before we dive into a test-driven example, let’s quickly summarize the basics of TDD...
TDD steps:
- Write a requirements based test
- Run the test and watch it fail
- Write the shortest, simplest solution to pass the test
- Run the test and watch it pass
- Refactor the test
- Ensure your designed units are testable
- Ensure you understand the requirements (see tire swing diagram)
The example that follows requires PSUnit. To install PSUnit, download PSUnit, extract the zip file contents, import the project, and build the project’s records. The version downloadable from the PeopleTools blog : PSUnit: Unit test framework for PeopleSoft was built using PeopleTools 8.49, but should run on recent versions of PeopleTools 8.4x. The project includes the role TTS_UNIT_TEST. Once you add this role to your user profile, you will gain access to the online run component for PSUnit.
The best way to describe PSUnit is to test drive it with a TDD example. In this example, we will create a new tool to help debug applications. Here is the scenario:
You, the developer, receive a notification from a user that page X of component COMP_X is calculating the wrong values. The user informs you that the calculation and error occur when he/she clicks save. From this information, you speculate that the calculation happens in the SavePreChange or SavePostChange event of the component or some record used in the component. Unfortunately, you are not familiar with this page or component.
With a PeopleCode trace, you are able to identify six potential events. You notice that these events call FUNCLIB’s and App Classes creating a horrendously deep call stack. From what you have in front of you, it is obvious that a quick review of this 3,000+ line trace file won’t provide an easy solution.
At this point you have several options:
- Continue to treat COMP_X as a black box, investigating it from the outside.
- Dig into the code and speculate as to its purpose.
- Configure app server debugging and step through the deep call stack.
- Start adding MessageBox statements to the delivered code so you can interrogate the state of the application as it runs.
What I want is a logging facility that allows me to write statements like:
&logger.debug("Program made it to line 30");
&logger.debug("Number of rows in rowset: " | &rs);
And, I want to leave those statements in my code, turning them on and off as needed. I don’t want to waste the effort I invested in writing targeted debugging statements, assuming I will need them at another time.
At this point, we know what we want to accomplish, but not how. TDD suggests that if we start with what we know, then what we don’t know will become evident.
method testLogger()
Local Logger &logger = create Logger();
&logger.debug("Program made it to line 30");
&logger.debug("Number of rows in rowset: " | &rs);
end-method;
From this test case, we see that we need a Logger object that implements a debug method.
With this information, let’s create a stub for the Logger App Class.
class Logger
method debug(&message as string);
end-class;
method debug
end-method;
At this point, our test case appears to test two things:
- Object creation/construction
- debug method execution
Our original intent was to display a message using the MessageBox function. Looking at the debug method, we could satisfy this requirement with one line:
method debug
/+ &message as String +/
MessageBox(0, "", 0, 0, &message);
end-debug;
The problem with this approach is that it is not testable. Even if it were testable, the behavior of this debug method would require us to test the MessageBox function, a delivered function that is outside the scope of our project.
When we implement the on/off switch for our logging facility, we will want a way to test the logic of the debug method without testing the MessageBox statement. As an alternative, let’s delegate the debug printing logic to another class. This level of abstraction will allow us to extend our logging facility to log to files, databases, sockets, etc. Most importantly, this level of abstraction will allow us to test the debug method without testing the MessageBox statement.
With this new design in mind, let’s set aside our original testLogger test case to develop a log target we can use to test the debug method. As always, we will start with step 1: develop a test. This time, however, we will develop our test case using the PSUnit test framework.
We define PSUnit test cases as Application Classes that extend the base class TTS_UNITTEST:TestBase (see Figure 1). TestBase provides the standard xUnit Setup, Teardown, and assertion methods as well as a single Run method. Setup code goes in the Setup() method, cleanup code goes in the Teardown() method, and test code goes in the Run() method. Most of the assertion methods are self explanatory. The Assert method requires a boolean test parameter and a string message parameter. If the boolean parameter is false, then the Assert method throws an exception, giving the message parameter as the Exception’s text. The rest of the assertion methods are similar except these other methods compare the first two parameters for equality.
One way to verify the Logger’s debug logic is to buffer printed log statements in a string and then compare the buffer contents to the strings we printed. Let’s write a test for this logging target:
method Run
Local StringBufferTarget &target = create StringBufferTarget();
&target.print("Hello World");
%This.AssertStringsEqual(&target.getBuffer(), "Hello World", "method failed");
end-method;
This test creates an instance of the StringBufferTarget class, calls the print method, and then compares the contents of the class’s string buffer to the printed data.
Listing 1 contains the full TestStringBufferTarget class test case. Add this code to a new package named ADS_LOG_TEST.
| Listing 1 TestStringBufferTarget |
| import TTS_UNITTEST:TestBase; import ADS_LOGGER:StringBufferTarget; class TestStringBufferTarget extends TTS_UNITTEST:TestBase method TestStringBufferTarget(); method Run(); end-class; method TestStringBufferTarget %Super = create TTS_UNITTEST:TestBase("TestStringBufferTarget"); end-method; method Run /+ Extends/implements TTS_UNITTEST:TestBase.Run +/ Local ADS_LOGGER:StringBufferTarget &target = create ADS_LOGGER:StringBufferTarget(); &target.print("Hello World"); %This.AssertStringsEqual(&target.getBuffer(), "Hello World", "method failed"); end-method; |
Before saving this test code (TestStringBufferTarget), we need to create a stub for the StringBufferTarget class. Create a new Application Package named ADS_LOGGER and a new class named StringBufferTarget:
class StringBufferTarget
method print(&message as string);
method getBuffer() returns string;
end-class;
method print
end-method;
method getBuffer
return "";
end-method;
As you read through this document, you will notice that we are writing code that depends on objects we have not defined. This is intentional. By starting with the external interface, we are actually designing the internal components. This outside-in development strategy drives the design of these lower level components. The unfortunate side effect when writing PeopleCode in this manner is that you cannot save code that depends on objects that don't exist. As Listing 1 demonstrates, we cannot save the test case until we create a basic stub for the StringBufferTarget class.
Our code is ready for step 2: Run the test and watch it fail. The test prints “Hello World” to the log target, but, as you can see from the code above, our log target’s getBuffer() method returns an empty string. When this code runs, the assertion will fail because “Hello World” <> “”. In step 2, we run tests we know will fail to prove they fail. If we write a test that passes before we implement behavior, then we know the test is flawed. This first run of our test case provides minimal validation of the test.
To run this test using the PSUnit test framework, launch your browser, connect to your PeopleSoft instance, navigate to PSUnit, and add a new value.
When the psUnit 1.1 test suite opens in your browser, switch to the Add/Delete Tests tab. Before executing this test suite, we need to add the new TestStringBufferTarget test class.
Switch back to the Run Tests tab, click Select All, and then click Run Tests. You should see a red square indicating the test failed.
Moving on to step 3, our goal is to write as little code as possible to make our test pass. It doesn’t matter how we make this test pass. Like step 2, step 3 is more concerned with validating test logic than testing implementation logic. We will clean up the code in step 5.
Considering the simplicity of the StringBufferTarget, I am sure you already know the code you would write to implement the print and getBuffer methods. At this stage, resist the temptation to write the obvious implementation. Remember, we are trying to validate the test, not the implementation. My first cut at implementing this class follows:
class StringBufferTarget
method print(&message As string);
method getBuffer() Returns string;
end-class;
method print
/+ &message as String +/
end-method;
method getBuffer
/+ Returns String +/
Return "Hello World";
end-method;
Notice that I hard coded the result. Again, this is to validate the test case, not the implementation. We will refactor this code in step 5.
Step 4: Run the test again and watch as the indicator flips from red to green.
Well, actually, as you see from the screen print above, psUnit 1.1 result (‘Passed’) doesn’t flip to green upon success. It flips to an anti-climatic white. As an experienced PeopleTools programmer, I am sure you know how to fix this (if not, check the code that flips it red).
On to step 5... it is time to refactor this code to eliminate redundancy, remove magic numbers, etc. For example, the string “Hello World” exists in our test code and our implementation. We can eliminate this redundancy by adding a private instance variable to store strings written to the print method and then display those strings with the getBuffer() method.
class StringBufferTarget
method print(&message As string);
method getBuffer() Returns string;
private
instance string &buffer_;
end-class;
method print
/+ &message as String +/
&buffer_ = &buffer_ | &message;
end-method;
method getBuffer
/+ Returns String +/
Return &buffer_;
end-method;
For the sake of brevity, I made 3 changes at once. Pure TDD suggests making one change at a time, testing between each change. If refactoring causes a test to fail, single step modifications are the easiest way to identify the failure’s cause.
Testing our code one more time shows these changes were successful. Since we are running this code interactively, it would be nice to see some output describing the test’s accomplishments. Let’s use the Msg method of TestBase to print comments to the PSUnit test page. Listing 2 contains the code for this modified test case. Notice that I eliminated the “Hello World” redundancy as well.
| Listing 2 TestStringBufferTarget, version 2 |
| import TTS_UNITTEST:TestBase; import ADS_LOGGER:StringBufferTarget; class TestStringBufferTarget extends TTS_UNITTEST:TestBase method TestStringBufferTarget(); method Run(); end-class; method TestStringBufferTarget %Super = create TTS_UNITTEST:TestBase("TestStringBufferTarget"); %This.Msg("TestStringBufferTarget: constructor"); end-method; method Run /+ Extends/implements TTS_UNITTEST:TestBase.Run +/ %This.Msg("TestStringBufferTarget: Run"); Local ADS_LOGGER:StringBufferTarget &target = create ADS_LOGGER:StringBufferTarget(); Local string &message = "Hello World"; Local string &buffer; &target.print(&message); &buffer = &target.getBuffer(); %This.Msg("TestStringBufferTarget: printed :" | &message); %This.Msg("TestStringBufferTarget: buffer :" | &buffer); %This.AssertStringsEqual(&buffer, &message, "method failed"); end-method; |
Running this code again, we see that %This.Msg(string) prints text to the Messages group box.
Recapping the process thus far, we started with a logger. The logger’s test identified the need for a target. Since we didn’t have a target, we set the logger’s test aside and used TDD steps 1 through 5 to design and implement a target. With this target complete, we can return to step 1: write a test for the logger. When we write the test this time, we will create it as a PSUnit test case in the ADS_LOG_TESTS Application Package.
| Listing 3 TestLogger Test Case |
| import TTS_UNITTEST:TestBase; import ADS_LOGGER:StringBufferTarget; import ADS_LOGGER:Logger; class TestLogger extends TTS_UNITTEST:TestBase method TestLogger(); method Run(); end-class; method TestLogger %Super = create TTS_UNITTEST:TestBase("TestLogger"); %This.Msg("TestLogger: constructor"); end-method; method Run /+ Extends/implements TTS_UNITTEST:TestBase.Run +/ %This.Msg("TestLogger: Run"); Local ADS_LOGGER:StringBufferTarget &target = create ADS_LOGGER:StringBufferTarget(); Local ADS_LOGGER:Logger &logger = create ADS_LOGGER:Logger(); Local string &message = "Hello World"; Local string &buffer; &logger.setTarget(&target); &logger.debug(&message); &buffer = &target.getBuffer(); %This.Msg("TestLogger.Run: printed: " | &message); %This.Msg("TestLogger.Run: buffer: " | &buffer); %This.AssertStringsEqual(&buffer, &message, "method failed"); end-method; |
Listing 3 contains the code for this rewritten test case. This code further clarifies the Logger interface by demonstrating the need to identify a logger’s target. Even though I chose to implement this behavior using the setLogger(&target) mutator method, constructor injection would be equally satisfactory. Let’s add this new method to the Logger stub and make Logger a member of the ADS_LOGGER Application Package.
import ADS_LOGGER:Target;
class Logger
method debug(&message as string);
method setTarget(&target as Target);
end-class;
method debug
end-method;
method setTarget
end-method;
The setTarget parameter type Target is a placeholder for the StringBufferTarget we previously created. We want to strongly type the target parameter while still allowing for flexible target implementations. We can provide this strongly typed flexibility by extracting the following interface from the StringBufferTarget class and adding it to our ADS_LOGGER Application Package:
interface Target
method print(&message as string);
end-interface;
For the Logger class to use the StringBufferTarget the StringBufferTarget must implement this new interface. To accomplish this, replace the first line of the StringBufferTarget class with the following two lines:
import ADS_LOGGER:Target;
class StringBufferTarget implements ADS_LOGGER:Target
Our Logger test is ready to run. Step 2: run the test and watch it fail.
In your web browser, add the ADS_LOG_TESTS:TestLogger test case to your PSUnit test suite and run the TestLogger test case.
Running this test should produce a red failure indicator. Listing 4 provides a solution for step 3: write the shortest, simplest solution to pass the test.
| Listing 4 Logger Implementation |
| import ADS_LOGGER:Target; class Logger method debug(&message As string); method setTarget(&target As ADS_LOGGER:Target); private instance ADS_LOGGER:Target &target_; end-class; method debug &target_.print(&message); end-method; method setTarget &target_ = &target end-method; |
Step 4: Run the test again and watch it pass.
With steps 1 through 4 complete, we can refactor this Logger. Looking at this code, however, I don’t see anything to refactor.
Our objective is to turn logging on and off without touching code. This implies some type of configuration. As TDD is an iterative process, this requirement takes us back to step 1: write a test. Rather than write a new test, giving us two tests that cover the same code, we can refactor the original test by adding coverage for this new requirement. Listing 5 contains this refactored TestLogger test case.
| Listing 5 TestLogger Test Case that Tests Configuration |
| import TTS_UNITTEST:TestBase; import ADS_LOGGER:StringBufferTarget; import ADS_LOGGER:Logger; class TestLogger extends TTS_UNITTEST:TestBase method TestLogger(); method Run(); private method Run_OnTest(); method Run_OffTest(); Constant &MESSAGE = "Hello World"; end-class; method TestLogger %Super = create TTS_UNITTEST:TestBase("TestLogger"); %This.Msg("TestLogger: constructor"); end-method; method Run /+ Extends/implements TTS_UNITTEST:TestBase.Run +/ %This.Msg("TestLogger: Run"); %This.Msg("TestLogger: Turn on logging"); SQLExec("UPDATE PS_ADS_LOG_CONFIG SET FLAG = 'Y'"); %This.Run_OnTest(); %This.Msg("TestLogger: Turn off logging"); SQLExec("UPDATE PS_ADS_LOG_CONFIG SET FLAG = 'N'"); %This.Run_OffTest(); end-method; method Run_OnTest %This.Msg("TestLogger.Run_OnTest"); Local ADS_LOGGER:StringBufferTarget &target = create ADS_LOGGER:StringBufferTarget(); Local ADS_LOGGER:Logger &logger = create ADS_LOGGER:Logger(); &logger.setTarget(&target); &logger.debug(&MESSAGE); %This.AssertStringsEqual(&target.getBuffer(), &MESSAGE, "method failed"); end-method; method Run_OffTest %This.Msg("TestLogger.Run_OffTest"); Local ADS_LOGGER:StringBufferTarget &target = create ADS_LOGGER:StringBufferTarget(); Local ADS_LOGGER:Logger &logger = create ADS_LOGGER:Logger(); &logger.setTarget(&target); &logger.debug(&MESSAGE); |
Our requirements call for two tests, an on test and an off test. To facilitate this requirement, I converted the Run method into a controller that updates the configuration and then calls the appropriate private test method. From the Run method, you can see that I chose to store the on/off configuration flag in a one row table named ADS_LOG_CONFIG with one field named FLAG. Before running this code, be sure to build a table named ADS_LOG_CONFIG with a single field called FLAG.
The Run_OnTest method is the same test from listing 3. The Run_OffTest method is similar to Run_OnTest except that the Run_OffTest method verifies that the log buffer contains no data. When you save and run this test (step 2), the Run_OnTest method will pass and the Run_OffTest method will fail. We can determine which private method failed by reviewing the call stack in the Errors group box. The test failed because the Logger class hasn’t implemented the on/off flag.
With this test validated, we can modify the Logger class (step 3) to implement this on/off behavior. Listing 6 contains the modified Logger code.
| Listing 6 Logger class that implements the on/off behavior |
| import ADS_LOGGER:Target; class Logger method Logger(); method debug(&message As string); method setTarget(&target As ADS_LOGGER:Target); private instance ADS_LOGGER:Target &target_; instance boolean &isOn; end-class; method Logger Local string &flag; SQLExec("SELECT FLAG FROM PS_ADS_LOG_CONFIG", &flag); If (&flag = "Y") Then &isOn = True; End-If; end-method; method debug /+ &message as String +/ If (&isOn) Then &target_.print(&message); End-If; end-method; method setTarget /+ &target as ADS_LOGGER:Target +/ &target_ = &target end-method; |
We are almost ready to test this Logger. Before testing, however, we have to configure it according to our new configuration parameter. For the sake of brevity, we will use SQL to set our configuration. For a production system, I recommend creating a page and component to manage the Logger's configuration. Here is the SQL to create our initial logger configuration. Run this SQL before continuing:
INSERT INTO PS_ADS_LOG_CONFIG VALUES('N')
/
COMMIT
/
Run the test again to see success (steps 4 and 5).
With our framework exhibiting the desired behavior, we can implement a MessageBox target to use for debugging.
| Listing 7 MesageBoxTarget class |
| import ADS_LOGGER:Target; class MessageBoxTarget implements ADS_LOGGER:Target method print(&message As string); end-class; method print /+ &message as String +/ /+ Extends/implements ADS_LOGGER:Target.print +/ MessageBox(0, "", 0, 0, &message); end-method; |
We can visually inspect the behavior of this new target with another test case. Unfortunately, we can’t automate this test with Asserts (MessageBox/JavaScript alert), but we can manually verify the MessageBox popup. Listing 8 contains the code for this test.
| Listing 8 MesageBoxTarget test case |
| import TTS_UNITTEST:TestBase; import ADS_LOGGER:MessageBoxTarget; import ADS_LOGGER:Logger; class TestMessageBoxTarget extends TTS_UNITTEST:TestBase method TestMessageBoxTarget(); method Setup(); method Run(); method Teardown(); private instance string &flag_; end-class; method TestMessageBoxTarget %Super = create TTS_UNITTEST:TestBase("TestMessageBoxTarget"); %This.Msg("TestMessageBoxTarget: constructor"); end-method; method Setup /+ Extends/implements TTS_UNITTEST:TestBase.Setup +/ Local string &flag; %This.Msg("TestMessageBoxTarget: Setup"); SQLExec("SELECT FLAG FROM PS_ADS_LOG_CONFIG", &flag); &flag_ = &flag; end-method; method Run /+ Extends/implements TTS_UNITTEST:TestBase.Run +/ %This.Msg("TestMessageBoxTarget: Run"); SQLExec("UPDATE PS_ADS_LOG_CONFIG SET FLAG = 'Y'"); Local ADS_LOGGER:Logger &logger = create ADS_LOGGER:Logger(); &logger.setTarget(create ADS_LOGGER:MessageBoxTarget()); &logger.debug("Hello World"); end-method; method Teardown /+ Extends/implements TTS_UNITTEST:TestBase.Teardown +/ Local string &flag = &flag_; %This.Msg("TestMessageBoxTarget: Teardown"); SQLExec("UPDATE PS_ADS_LOG_CONFIG SET FLAG = :1", &flag); end-method; |
Listing 8 introduces Setup and Teardown. The TestMessageBoxTarget class uses the Setup method to enable the framework’s database log flag and then uses Teardown to reset the flag. For each test case in a test suite, the interactive test runner runs Setup, Run, and then Teardown. Use Setup to put data, files, configurations, etc in the state expected by the test and use Teardown to reset changes made by Setup.
The test suite presented here is fairly small. As I expand this test suite by adding tests for new log framework features, the time required to run tests may cause the on-line user interface to timeout. PSUnit provides test chunking to work around this issue. The screenshot above shows an options group box with a chunking checkbox and a chunk size text box. If you enable chunking and set the size to 3, then PSUnit will run three tests, return, and then run the next three.
The online PSUnit automated test suite runs as FieldChange PeopleCode and, therefore, is subject to all the FieldChange PeopleCode rules (CommitWork, think-time actions, etc).
PSUnit is a test framework starting point. I encourage you to enhance it as needed. For example, PSUnit does not provide an offline test runner. Running tests offline through an AppEngine program would eliminate FieldChange limitations and allow developers to schedule long running tests to run after hours.
