How to Create a JUnit Load Test within ALT
- Glenn Huang (Unlicensed)
- Caleb Miller
JUnit is a test framework for software code that uses annotations to identify methods that specify a test. JUnit is an open-source project hosted at Github. A JUnit test is a method, contained in a class that is only used for testing (a.k.a Test class). This method executes the code under testing and can assert to check for the expected result versus the actual result.
Executing JUnit test cases in ZebraTester
Executing JUnit test cases with ZebraTester has been supported since ZebraTester version 5.1. A ZebraTester wizard automatically generates load test JUnit plug-ins (no manual programming needed). This allows users to run their own JUnit load tests on any load generator, providing helpful support for load generator clusters. Many thousands of JUnit test cases can run in parallel at the same time, and that all of the results are combined into one test report.
Setting up a JUnit Test
Step 1: Set up the Plugin from Within ZebraTester
Step | Illustration |
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1. Prepare a Session with one "Non Executable" URL CallFirst, you need a recorded session that contains only one URL call (that never will be executed). If you haven’t created any session, you can use the PageScanner tool or the Add URL to session. Or, you can load any existing session and remove all URL calls except the first one from that session and set the User's Think Time to a value of zero. | 
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2. Configure the URL call as "non-executable"For this example, we are going to take the URL call to the Apica Website and step you through the ZebraTester UI as to how to mark the call as non-executable. This is a special case as you would not normally do this except for a JUnit test case.
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3. Return to the Main MenuClick refresh to reload the current page. The URL call should now be shown with a yellow exclamation mark. | |
4. Add the JUnit Packages and the Test Package to the SessionBy clicking from the (1) ZebraTester Main Menu on the URL that we set as non-executable, we open the Var Handler page, and from that, we (2) look for the black folder icon that opens the Declare External Resources (for Self-Developed Plug-ins) menu. At the Declare External Resources menu and (3) add all Java *.jar files that are needed to execute the JUnit test. This means that you have to add the jar files of JUnit itself (for example, junit-4.11.jar and hamcrest-core-1.3.jar) and the jar file that contains your JUnit test (for example CollectionTest.jar), so you end up with a table/list of all declared external resources at the bottom of the dialog. (4) Note: We are continuing with the Apicasystems.com URL from above. |
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5. Add a System Properties File (Optional)You can also declare a System Properties File as an external resource. Such a file will be parsed on the load generators just before the JUnit tests are executed. The key and values of such a file are stored in the Java virtual machine as system properties. Hint: To debug the parsing of such a file you can enable the option "debug loops" when starting a load test. The debug output is written to the *.out file of the load test job.
| The lines of the file can contain the following commands:
Example saved and declared as an External Resource called “SystemProperties.txt”:
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Step 2: Generate a JUnit Load Test Plug-In
Step | Illustration |
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Once you have loaded all External Resources described in the How to Create a JUnit Load Test within ALT page, navigate to the Project Navigator to the Plugins directory and call the JUnit wizard with the Icon |
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In the wizard, enter the full class name of the JUnit test or Search for it in the “Find Class in External Resources.” |
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Select which JUnit test methods should be executed during the load test |
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Generate the JUnit Plug-In Code | |
Compile the Load Test Plug-in |
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Step 3: Add a JUnit Load Test Plug-In to Session
Once the Plug-In is generated, you can add it to a Load Testing Session.
Step | Illustration |
|---|---|
Iin the Project Navigator, navigate to the directory where the load test program should be generated. In this screenshot this is called ‘MyTests’ |
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Return to the Main Menu and add the JUnit Plug-In to the desired URL Call. | |
In the URL Details/Var Handler, locate the Load Test Plug-ins and click Add Plug-in |
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From the Var Handler, under, Add Load Test Plug-in, select the Defined Plug-ins from the dropdown box and Continue. | |
Add the Plug-in along with any additional parameters. | |
Note the Plug-in has been added, with any additional parameters. Save the session by clicking the “Save Session” icon. |
Step 4: Generate the Load Test Program with a JUnit Load Test Plug-In
Step | Illustration |
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From the Main Menu, Generate Load Test |
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On the Generate Load Test Program dialog, enter your Java Classname and click Continue
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In the Project Navigator, you’ll find your class file created in your selected directory. Click the Execute Load Test Icon.
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Before Executing a Load Test with a Plug-in, ZIP the Plug-ins and all external Local Resources before continuing to Executing. >>ZIP and execute | |
All JUnit plug-ins support to configure a Pacing Time (0 = no Pacing Time). The Pacing Time defines how much minimum elapsed-time a simulated user should spent in the plug-in.
| Example 1: If you configure a pacing time of 10 seconds and a simulated user executes the plug-in in 3 seconds the user will be delayed for 7 seconds in that executed loop (3 + 7 seconds = 10 seconds). Example 2: If you configure a pacing time of 10 seconds and a simulated user executes the plug-in in 2 seconds the user will be delayed for 8 seconds in that executed loop (2 + 8 seconds = 10 seconds). Example 3: If you configure a pacing time of 10 seconds and a simulated user executes the plug-in in 13 seconds the user will not be delayed in that loop (13 > 10 seconds) |
During the execution of the load test you can examine the measured errors at real-time | |
Under the Error Overview (Real-Time) Latest Error under the Latest Error Snapshots you can drill into any row with the magnifier icon. | |
Drilling down into the Error log for details | |
After the load test has been completed, and you have acquired the test result, you can display the execution time for each JUnit method |
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JUnit Best Practices
Configuring Timeouts for all JUnit Test Methods
In order to prevent a blocking/freezing of a JUnit load test, Apica strongly recommends that you configure a timeout for each test method for all your JUnit test cases. You can use large values for such timeouts as 15,000 milliseconds.
Example:
@Test(timeout=15000)
public void sortedSet() {
…Passing User-Specific Variables to JUnit Tests
JUnit by itself does not support passing any (local) per test-run specific variables to a test method.
However, as an example, when testing a Web service, it's often required that for each simulated user or each JUnit test run, we need to use a different username and password for authentication. So how do we do this?
The easiest way is to use a Text-File containing the values of such per test-run specific variables. Example:
Miller; abcd
Meier; topsecret
Sutter; password
To support this example, you should modify the program code of the JUnit test case as follows:
import java.io.*;
import dfischer.utils.Base64Decoder;
import dfischer.utils.StaticInputFile; // defined in prxsniff.jar – see also ZebraTester Java API Doc
import dfischer.utils.StaticInputFileLineContent;
import dfischer.utils.AbstractInputFileReader;
import dfischer.utils.SymmetricEncryptContext;
...
@Test(timeout=15000)
public void sortedSet() {
String username = "Miller"; // default value, used for non load test execution
String password = "abcd"; // default value, used for non load test execution
if ((System.getProperty("PrxJUnitLoadTest") != null) && System.getProperty("PrxJUnitLoadTest").equalsIgnoreCase("true")) {
try {
SymmetricEncryptContext decryptContext = null;
String decryptContextProperty = System.getProperty("PrxSymmetricEncryptContext");
if (decryptContextProperty != null) {
decryptContext = SymmetricEncryptContext.fromSerializedByteArray(Base64Decoder.decodeToBytes(decryptContextProperty));
}
int fileID = StaticInputFile.concurrentOpen(decryptContext, "Accounts.txt", "#", ";", true, AbstractInputFileReader. EOF_REOPEN_FILE);
StaticInputFileLineContent line = StaticInputFile.getNextLine(fileID);
username = line. getValue(0);
password = line. getValue(1);
}
catch (IOException ie) {
throw new RuntimeException("failed to read Accounts.txt", ie);
}
}
}
...Note that the System property "PrxJUnitLoadTest" = "true" is automatically set by ZebraTester when executing a JUnit load test.
The file containing the user accounts must also be declared as an external resource:
When using a cluster of load generators you can also split the file across the cluster members:
Modifying a JUnit Plug-In
To modify an already generated JUnit Plug-In navigate to the Plugins directory and click on the corresponding Template File:
After you have modified the plug-in, generate and compile the plug-in once again.
Please note that you have to confirm in Project Navigator that the old plug-in code should be overwritten and compiled (in two steps).
After these steps, navigate to the directory where the load test program is located and update the plug-in in this directory:
Once you Update the plug-in, the load test can be directly started.
Integration with Performance Monitoring Agent
The JUnit load test measured data can also be combined with the measured Operating System performance data on any machine where the Apica Performance Agent is installed (e.g. on Application Servers and on Database Servers). In order to accomplish this, you must select the corresponding "Monitoring Controller Template" when starting the JUnit load test:
The captured system performance data will also be added to the "External Measured Data":
JUnit Test Automation
There are four tools available that allow you to automatically generate ready-to-run load tests by using only a “JUnit Load Test Plug-In Template” as required input. The “JUnit Load Test Plug-In Template” contains information about which JUnit test cases should be executed during the load test.
Cannot find what you're looking for? Send an E-mail to support@apica.io.