Mainframe Software Testing

Mainframe Software Testing

In this article, I am going to discuss Mainframe Software Testing. Please read our previous article, where we discussed Database Testing. At the end of this article, you will understand the following essential pointers related to Mainframe Software Testing.

  1. What is Mainframe?
  2. What is Mainframe Software Testing?
  3. Where Did We Test the Mainframes?
  4. What are the Prerequisites for Mainframe Testing?
  5. Explain Mainframe Testing Methodologies
  6. What are Mainframe Attributes?
  7. How to Perform Mainframe Software Testing?
  8. Explain the Procedure to Follow in Mainframe Software Testing
  9. Explain Types of Mainframe Software Testing
  10. What are Mainframe Automation Testing Tools?
  11. What are the Advantages of Mainframe Software Testing?
  12. What are the Disadvantages of Mainframe Testing?
What is Mainframe?

A multi-user, high-performance, and high-speed computer system is the mainframe. The most dependable, scalable, and secure machine system is the mainframe. Put another way; we may argue that these systems are utilized for larger-scale computation, which requires high availability and safety. The mainframe systems are primarily used in various industries, including retail, insurance, finance, and other crucial sectors where enormous amounts of data are processed repeatedly.

With the assistance of the following elements, we can complete a million instructions per second [up to 569,632 MIPS]:

  1. Maximum Input/Output Bandwidth: If we have incredibly high input and output bandwidth, there are a few choke places in the connections between drives and CPUs.
  2. Reliability: The mainframes frequently consent to gentle deterioration and service while the system operates. For practical operations against a database, reliable single-thread performance is crucial.
  3. Maximum Input/Output Connectivity: The mainframes are excellent for supplying large disk farms because of their full input/output connectivity.
What is Mainframe Software Testing?

The primary goal of mainframe testing is to determine whether an application or service is prepared for deployment by using verification and validation techniques to ensure its dependability, performance, and perfection. Since the CICS screens’ navigations are tailored for specific applications, the tester must be familiar with them when completing the mainframe testing. And if any changes are made to the COBOL, JCL, or other code, the tester should not worry about the emulator configuration on the system. Software applications and services based on mainframe systems are tested through mainframe testing.

Where Did We Test the Mainframes?

The deployed code is typically used to run the mainframe testing, and multiple data combinations are usually inserted into the input file. To put it another way, we can say that the Mainframe Applications must undergo thorough testing before going into production.

The batch task, the mainframe application, is tested against the test cases developed per the requirements. You can access mainframe-compatible software or applications using the terminal emulator.

What are the Prerequisites for Mainframe Testing?

Some of the prerequisites for mainframe testing are as follows:

  1. To use the application, you must create a login ID and password.
  2. A fundamental understanding of ISPF commands.
  3. File names, file qualifiers, and file types are all listed.

Before beginning mainframe testing, the following points should be reviewed.

  • Before starting a job, do a job scan (Command – JOBSCAN) to check for errors.
  • The CLASS argument should be used to specify the test class.
  • The task output can be directed to a spool, a JHS, or anywhere else using the MSGCLASS argument.
  • Redirect the email from the job to a spool or a test mail ID.
  • Leave the FTP steps uncommented for preliminary testing and point the job to a test server.
  • If the job creates an IMR (Incident Management Record), note “TESTING PURPOSE” on the job or parameter card.
  • All of the production libraries in the task should be converted to test libraries.
  • Leaving the job unattended is not a good idea.
  • If there is an error, the TIME parameter should be provided with a time to prevent the job from running in an infinite loop.
  • Save the job output, including the Spool. XDC can store the spool data.
  • Create only a test file of the desired size. GDGs (Generation Data Groups – Files with the same name but sequential version numbers- MYLIB.LIB.TEST.G0001V00, MYLIB.LIB.TEST.G0002V00, and so on) are used when saving data into successive files with the same name.
  • The DISP (Disposition – describes the mechanism for keeping or deleting the dataset following a normal or abnormal step or job termination) parameter should be carefully coded in the files.
  • To avoid the work being placed on HOLD, ensure that all files used for job execution are correctly saved and closed.
  • If you’re testing with GDGs, make sure you’re using the correct version.
  • Ensure no unwanted data is introduced, altered, or removed while the job or online application executes.
  • Additionally, ensure that you are testing in the correct DB2 region.
Test Case:
  • Always look for boundary conditions such as an empty file, the first or final record being processed, etc.
  • When feasible, include both positive and negative test conditions.
  • Include test cases to assess if the modules were used appropriately if standard software techniques such as checkpoint restart, Abend Modules, Control files, and so on are used.
Test Data:
  • Make sure the test data is ready before you begin testing.
  • Never modify the data in the test region without first telling the user. Other teams may be working with the same data and experiencing failures in their testing.
  • Before copying or accessing the production files, gain proper authorization.
Explain Mainframe Testing Methodologies

The following are some of the most regularly used Mainframe testing commands:

  • SUBMIT: Use this command to submit the background job.
  • CANCEL: Use this command to cancel the background job.
  • ALLOCATE: This command is used to allocate a dataset.
  • COPY: A dataset is copied using this command.
  • RENAME: This command renames the dataset.
  • DELETE: This command deletes the dataset.
  • JOB SCAN: Without using libraries, program files, or other implementation methods, this command is used to fix the JCL.
What are Mainframe Attributes?

The following are some of the mainframe characteristics:

What are Mainframe Attributes?

  1. The multiprogramming function allows us to make the most of the CPU.
  2. Many apps are operating on the computer at the same time.
  1. Time-share processing is referred to as foreground processing, whereas batch job processing is referred to as background processing. As a result, it is known as Interactive Processing since it allows the user to engage with the computer directly.
  2. Each user in a time-sharing system has terminal device access to the system.
Virtual Storage:
  1. Virtual storage uses disc storage as an extension of physical storage.
  2. It is a technique for efficiently storing and performing many operations using memory.
  1. The Spool is an acronym for Simultaneous Peripheral Operations Online, and it is used to collect the output of a program or application.
  2. If necessary, the spooled output is forwarded to output devices such as a printer.
Batch Processing:
  1. Batch processing is a technique that allows us to perform any task in chunks known as tasks.
  2. Depending on the tasks, one or more apps can be run in a particular order.
  3. The job scheduler decides the order in which the jobs are done.
  4. Jobs are prioritized and classified to enhance average production.
  5. Batch processing supplies us with the essential information (JCL) with the help of JOB CONTROL LANGUAGE.
How to Perform Mainframe Software Testing?

Testing on mainframes can be carried out manually or automatically using tools like QTP, REXX, and IBM Application Performance Analyzer. However, we will typically perform the Mainframe testing manually. To perform mainframe testing, we must first complete the following steps:


To begin, the business or development team creates the test plans, which include the Business requirement document, System requirement document, other project documents, and inputs. And it determines how a specific item or process will be altered within the release cycle. Meanwhile, the testing team will collaborate with the development and project management teams to prepare the test scenarios and cases beforehand.


The development and testing teams will receive the requirement document once correctly created. A precise project delivery plan should also be recorded with the testing timetable.


They will review the deliverables after they have the document. Additionally, the deliverables should be accurately described without confusion and meet the objectives of the test’s scope.


The plan and deliverables should then carry out the implementation. Typically, the modified requirement in a release will directly impact 15–25% of the application. And the remaining 60–75% of the release will rely on things that are not included, such as testing the processes and apps. Therefore, we must conduct two types of tests on the Mainframe application:

  • Testing Conditions: We will test the application for the features or the modifications disclosed in the requirement document—integration testing requirements.
  • Testing Integration: Regression testing for integration The focus of this testing activity is testing. Additionally, we will try the complete procedure and any other software that sends or receives data for the valuable application.

We will periodically update the development team on the test results. The testing team must communicate with the development team to preserve continuity and make quick adjustments as necessary.

Explain the Procedure to Follow in Mainframe Software Testing

Keep in mind the following procedures when testing mainframes:

Smoke Testing:

To check whether the deployed code is in the appropriate test environment, perform a smoke test first. Additionally, it guarantees that the code is devoid of critical faults, saving testers’ time and effort from testing a subpar build.

System Testing:

After the smoke test, a round of functionality or system testing will be conducted to assess the functions of various models separately and in connection. The following is a list of the types of testing that must be done while implementing system testing:

  • Batch Testing: Perform batch testing to ensure that the output files and data changes generated by the batch job are by the testing requirements.
  • Online Testing: Assess the front-end capabilities of the mainframe applications using online testing. Online testing covers various themes, such as screen navigation, look and feel, data input validations, and user-friendliness. The application should test all exact entry fields, including interest in the plan, an insurance plan, and others.
  • Online-Batch Integration Testing: This testing can be done on systems with batch operations and online applications. How well the online process integrates with the backend procedure will also be checked. In essence, this testing checks to ensure accurate data flow and communications between the screens and the backend system. The batch task is also used to check the transmission and flow of data among the web screens.
  • Database Testing: Database testing ensures that the information recorded by transactions complies with the system’s specifications. Additionally, the databases confirmed the design and data storage of the mainframe programs, including IMS, IDMS, DB2, VSAM/ISAM, Sequential datasets, and GDGs. Data integrity and other database parameters may also be checked during database testing for optimal performance.
System Integration Testing:

System integration testing ensures that systems connected to the tested method perform correctly. It is run after unit tests since trying the user interface and various messages, like Job Successful, Job Failed, Database Updated, etc is crucial. The correctness of the data flow between modules and apps will also be examined. System integration testing is performed to ensure the build is prepared for deployment. In system integration testing, the following tests can be run:

  1. Batch Testing
  2. Online Testing
  3. Online -Batch Integration Testing
Regression Testing:

The most critical component of any testing is regression testing. Regression testing ensures that online screens and batch operations are not directly related to the system being tested and are unaffected by the most recent project release. Regression testing ensures that modifications to a module don’t affect the integrated application’s overall functionality. To successfully perform regression testing, a repository for test cases should be created, and a specific set of test cases should be accepted based on their difficulty. And each time a new feature is included in the release, the particular test should be updated.

Performance Testing:

Performance testing is the subsequent stage of mainframe testing. The objectives include finding bottlenecks in crucial areas like front-end data, updating online databases, and safeguarding the application’s scalability during performance testing. The following performance issues can occur with Mainframe applications:

  • User annoyance may result from a slow internet response time.
  • Online users’ access to the system may be constrained by batch jobs and backend procedures that take longer than anticipated.
  • Problems with scaling.

Run the application through the following tests to address the issues above:

  • Parameters for integrating a system.
  • Designing code for applications and databases.
  • Parameters for the database and the system.
  • Scheduling jobs in the back.
Security Testing:

Applications and networks should take corrective action after assessing threats, dangers, and vulnerabilities. The security testing should cover use cases for identity and access management, risk and compliance management, data protection, and adherence to privacy policies. To put it another way, security testing examines how well-built and planned an application is to fend off security threats. Mainframe and network security are the two categories of security systems that must be tested. When conducting security testing, the following elements must be examined:

  • Authorization
  • Integrity
  • Authentication
  • Confidentiality
  • Availability
Agile Methodologies:

The Agile technique is designed to streamline the development of applications gradually and reacts fast to change.

Explain Types of Mainframe Software Testing

The two components of mainframe manual testing are as follows:

  1. Online Testing: Online testing is conducted via the member enrolling screen. Like a web page, the database is validated using data entered through the displays.
  2. Batch Job Testing: This technique is tested in two steps: first, each job is separately validated; second, the integration between the positions is verified by giving the first job an input flat file and demonstrating the database. (Improved caution necessitates confirmation of interim outcomes.)

What are Mainframe Automation Testing Tools?

There are several different mainframe automation testing tools on the market. The following are some of the most popular mainframe automation testing tools:

  1. QTP
  2. REXX

The web-based application’s functional regression cases are tested using the QTP tool. Quick Test Professional, or Micro Focus UFT [Unified Functional Testing], was formerly known as QTP. The fact that a fresh test engineer may immediately grasp the use of this tool is quite beneficial. To automate an application, QTP was created using a scripting language similar to VB script.

Qualities of QTP

The following are some of QTP’s most typical features:

  1. We can conduct BPT [Business process testing] using this technology.
  2. The objects are deployed using scripting language by QTP, and it offers test reports for analysis.
  3. Technical and non-technical testers can use QTP.
  4. QTP supports a variety of software development environments, including Oracle, SAP, and Java. With QTP’s assistance, we can test both desktop and web-based applications.

It was created at IBM and is an interpreted programming language. A high-level, organized programming language called REXX was explicitly designed for reading and learning. Restructured Extended Executor is referred to as REXX. It is employed as a macro and scripting language. To put it another way, we could say that REXX is widely used to process text and data and produce reports. It supports several operating systems, including VM, OS/2, MVS, and AmigaOS. Other programs like KEDIT, the ZOC terminal emulator, SPFPC, and others can use REXX as an internal macro language.

Qualities of REXX

The following are REXX’s most typical characteristics:

  1. The variable names are contained in tokens that support case insensitivity.
  2. We may quickly access system services and commands by utilizing REXX.
  3. The REXX supports different instructions, functions, and procedures specific to a particular circumstance.
  4. It supports fundamental input/output benefits.
  5. It does not require declarations to provide dynamic data typing.
What are the Advantages of Mainframe Software Testing?

We will benefit in the following ways by executing the mainframe testing process:

  • It utilizes resources most effectively.
  • It aids in avoiding unnecessary rework.
  • The user’s experience is enhanced.
  • It cuts down on production pauses.
  • It aids in increasing customer retention for us.
  • Additionally, it aids in lowering the overall cost of IT operations.
What are the Disadvantages of Mainframe Testing?

The drawbacks of Mainframe Testing are:

  • Costly infrastructure: Setting up and maintaining mainframe testing environments can be expensive due to the unique hardware and software requirements.
  • Access to mainframes may be restricted, which could cause testing to take longer than expected and create bottlenecks.
  • Complex test data management can make creating and maintaining test data sets difficult because managing enormous amounts of data on mainframes can be problematic.
  • Setting up the mainframe environments for testing can take some time and slows down the whole testing process.
  • Scalability problems: Modern applications’ growing demands may be too much for managing mainframes, limiting testing scalability.

In the next article, I am going to discuss Adhoc Software Testing. Here, in this article, I try to explain Mainframe Software Testing. I hope you enjoy this Mainframe Software Testing article.

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