# KRE command line parallel headless mode execution not working

**URL:** <https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107>\
**Category:** Test management\
**Tags:** katalon-runtime-engi, kre, headless, parallel, web-testing\
**Created:** [March 22, 2025, 1:22pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107 "2025-03-22T13:22:27Z")\
**Posts on this page:** 20\
**Page:** 1

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**Author:** ![vasanthi.jayakumar](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/vasanthi.jayakumar/32/16104_2.png) [@vasanthi.jayakumar](https://forum.katalon.com/u/vasanthi.jayakumar)\
**Post date:** [March 22, 2025, 1:22pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/1 "2025-03-22T13:22:27Z")

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QI want to run test suite collection with parallel chrome headless mode in KRE command line but it stopping for fetching driver details … can someone help

Note: It works for below test suite collection

1. Sequential-chrome
2. Parallel-chrome
3. Sequential-chrome(headless)

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**Author:** ![Elly\_Tran](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/elly_tran/32/21874_2.png) [@Elly\_Tran](https://forum.katalon.com/u/Elly_Tran)\
**Post date:** [March 22, 2025, 1:22pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/2 "2025-03-22T13:22:27Z")

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Hi there, and thanks for posting in the Katalon community! 🤗

To help you faster, please review our guide on Chrome Headless here:

- [Headless Browsers Execution in Katalon Studio | Katalon Docs](https://docs.katalon.com/katalon-studio/execute-tests/headless-browsers-execution-in-katalon-studio).
- [https://katalon-inc.my.site.com/katalonhelpcenter/s/article/What-are-the-best-practices-or-tips-when-working-with-headless-browsers](https://katalon-inc.my.site.com/katalonhelpcenter/s/article/What-are-the-best-practices-or-tips-when-working-with-headless-browsers).

Double-checking the steps and configurations might resolve the issue.

If the doc doesn’t help, feel free to provide more details, and a community member will assist you soon.

Thanks for being a part of our community!  
Best,  
Elly Tran

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<div class="post-metadata">

**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [March 22, 2025, 10:57pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/3 "2025-03-22T22:57:33Z")

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> [@vasanthi.jayakumar](#):
>
> but it stopping for fetching driver details

Could you share the error log?

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<div class="post-metadata">

**Author:** ![vasanthi.jayakumar](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/vasanthi.jayakumar/32/16104_2.png) [@vasanthi.jayakumar](https://forum.katalon.com/u/vasanthi.jayakumar)\
**Post date:** [March 23, 2025, 5:13am UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/4 "2025-03-23T05:13:48Z")

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No error thrown… it didn’t execute after this line

Checking WebDriverManager  
Verify built-in web driver manager  
Using built-in file

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<div class="post-metadata">

**Author:** ![dineshh](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/dineshh/32/24488_2.png) [@dineshh](https://forum.katalon.com/u/dineshh)\
**Post date:** [March 23, 2025, 5:31am UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/5 "2025-03-23T05:31:25Z")

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share the debug logs from your KRE run

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<div class="post-metadata">

**Author:** ![dineshh](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/dineshh/32/24488_2.png) [@dineshh](https://forum.katalon.com/u/dineshh)\
**Post date:** [March 23, 2025, 5:36am UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/6 "2025-03-23T05:36:16Z")

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To resolve issues with running KRE test suites in **parallel headless Chrome mode** , follow these steps:

## 1. **Check ChromeDriver Compatibility**

- Ensure your `chromedriver` version matches your installed Chrome browser version.
- Download the correct version from [ChromeDriver Downloads](https://sites.google.com/chromium.org/driver/).
- Verify the path to `chromedriver` is correctly configured in KRE’s settings.

## 2. **Update KRE and Dependencies**

- Upgrade KRE to the latest version:

```auto
npm update -g kre

```

- Update related packages (e.g., `selenium-webdriver`, `chromedriver`).

## 3. **Configure Headless Mode Properly**

Explicitly define headless Chrome options in your KRE configuration file (e.g., `kre.config.js`):

```auto
const { Options } = require('selenium-webdriver/chrome');

module.exports = {
  browsers: {
    chrome_headless: {
      browserName: 'chrome',
      headless: true,
      chromeOptions: new Options()
        .addArguments('--headless=new') // Use new headless mode
        .addArguments('--no-sandbox')
        .addArguments('--disable-dev-shm-usage')
        .addArguments('--disable-gpu')
    }
  },
  parallel: true, // Enable parallel execution
  maxParallelThreads: 4 // Set based on your system's CPU cores
};

```

## 4. **Allocate More Resources**

- Headless Chrome can be resource-intensive. Limit parallel threads to avoid overloading your system:

```auto
module.exports = {
  maxParallelThreads: 2 // Start with a lower number
};

```

## 5. **Debugging and Logs**

- Run KRE with verbose logging to identify the exact failure point:

```auto
kre run --config ./kre.config.js --log-level=debug

```

- Check for errors like:
  - `WebDriverError: unknown error: DevToolsActivePort file doesn't exist` (add `--remote-debugging-port=9222` to Chrome arguments).
  - `Unable to discover open pages` (ensure Chrome flags are configured correctly).

## 6. **Troubleshoot Environment Issues**

- Temporarily disable firewalls/antivirus software.
- Run tests in a clean environment (e.g., Docker container) to isolate conflicts.

## 7. **Example Working Command**

```auto
kre run --browsers=chrome_headless --parallel --workers=2

```

## 8. **Known Workarounds**

- If using legacy headless mode, replace `--headless=new` with `--headless=chrome`.
- Ensure Chrome is installed system-wide (e.g., `/usr/bin/google-chrome` on Linux).

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<div class="post-metadata">

**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [March 23, 2025, 11:27am UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/7 "2025-03-23T11:27:36Z")

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> [@vasanthi.jayakumar](#):
>
> I want to run test suite collection with parallel

Let me ask you a question.

In the Katalon documentation, the word “parallel” means 2 different features.

1. [Katalon Studio / Execute Test Suite Collections / parallel mode](https://docs.katalon.com/katalon-studio/execute-tests/execute-test-suite-collections-in-katalon-studio#parallel-mode)

2. [Test Ops / Run multiple test suites in parallel with Agents](https://docs.katalon.com/katalon-platform/execute/test-execution-with-testops/local-test-environments/run-multiple-test-suites-in-parallel-with-agents)

These 2 features use a single word “parallel” but these are completely different. You shouldn’t confuse them.

@vasanthi.jayakumar

Which “parallel” do you mean?

I guess, you mean the #1 — Parallel mode execution of a single Test Suite Collection. Am I right?

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<div class="post-metadata">

**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [March 23, 2025, 11:49am UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/9 "2025-03-23T11:49:56Z")

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As far as I see, Katalon designed the #1 “executing Test Suite Collection in parallel mode” poorly. It brought a lot of problems to me. So I am determined not to touch it. Instead, I just prefer the sequential mode — it works stable, as you already noticed.

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<div class="post-metadata">

**Author:** ![vasanthi.jayakumar](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/vasanthi.jayakumar/32/16104_2.png) [@vasanthi.jayakumar](https://forum.katalon.com/u/vasanthi.jayakumar)\
**Post date:** [March 23, 2025, 12:29pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/10 "2025-03-23T12:29:15Z")

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Yes.. I mean the #1 in KRE Command line execution

For the #1 at least 4instances should work right

Or

Any maximum instance suggestion…

- As I’m doing KRE command line execution for first time, I also need some suggestions on best approach… currently we have 57 suites in single testsuitecollection and asked to run in KRE commandline in remote machine…. We have one KS license and one KRE floating license…. Give me some suggestions for faster and better execution ways
- 

@kazurayam  
@dineshh

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<div class="post-metadata">

**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [March 23, 2025, 12:30pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/11 "2025-03-23T12:30:30Z")

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I don’t know, as I do not use #1, and I have no KRE licenses.

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<div class="post-metadata">

**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [March 23, 2025, 12:34pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/12 "2025-03-23T12:34:23Z")

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I could execute a Test Suite Collection with parallel mode using a single license of Katalon Studio GUI Free while specifiying 3 as the maxium parallel processes. ---- though I specified “parallel” but actually the TSC ran slowly, so that no quicker than the sequential mode.

This proves that Test Suite Collection with parallel mode requires only 1 license of Katalon Studio GUI Free.

Based on this observation, I guess that a execution of Test Suite Collection with parallel mode requires only 1 active license. Rather, I believe that **the number of licenses is not checked at all in the case of #1 parallel mode**.

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<div class="post-metadata">

**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [March 23, 2025, 12:38pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/13 "2025-03-23T12:38:37Z")

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> [@vasanthi.jayakumar](#):
>
> but it stopping for fetching driver details

I guess that the number of KRE license has nothing to do with your current problem.

As far as I see, the “Test Suite Collection in parallel mode” is unstable, problematic. I would recommend you not to touch it. It would waste your time.

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**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [March 23, 2025, 12:51pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/14 "2025-03-23T12:51:27Z")

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If you are eager for “parallelism”, you should look at the #2 parallelism. Actually I do not know it at all, but as far as I read the [Katalon’s doc](https://docs.katalon.com/katalon-platform/execute/test-execution-with-testops/local-test-environments/run-multiple-test-suites-in-parallel-with-agents), #2 seems to be better (better tested possibly) than #1.

In the #2, if you want 4 TestOps Agents to work in parallel, I believe that you need at least 4 KRE licenses. Simple, isn’t it?

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**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [March 23, 2025, 12:57pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/15 "2025-03-23T12:57:32Z")

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> [@vasanthi.jayakumar](#):
>
> currently we have 57 suites  
> …  
> Give me some suggestions for faster and better execution ways

Parallel execution of bulky Test Suites on a single machine won’t run any quicker than a sequential execution. On a single box, even if you tell a Test Suite Collection to execute multiple Test Suites in parallel, in fact the test suites run nearly sequentially. Why? Each individual Test Suite makes the machine fully occupied. So OS will allocate the CPUs+memory resources just sequentially to the Test Suites one after the other.

If @vasanthi.jayakumar wants process the bulk of Test Suites more quickly, he definitely needs to allocate multiple machines. Each machines should equip enough CPUs and memory. And he wants to distribute the bulky Test Suites into the nodes; monitor the distributed execution; collect the results and compile a final report. The more number of machines, the quicker the processing duration could be.

On the Internet, I could find some articles how to implement a distributed processing of Selenium tests. For example, with AWS, we can distribute selenium tests over mutliple nodes instanciated using ECS Fargate:

> **[GitHub - aws-samples/run-selenium-tests-at-scale-using-ecs-fargate: This article talks about an approach that can help...](https://github.com/aws-samples/run-selenium-tests-at-scale-using-ecs-fargate)**
>
> This article talks about an approach that can help customers run integration and regression tests quicker and cheaper to improve the CI/CD process.

Browserstack publishes the following article:

> **[Parallel Testing: The Essential Guide | BrowserStack](https://www.browserstack.com/guide/what-is-parallel-testing)**
>
> What is Parallel Testing? A detailed guide on how to perform Parallel Testing, with industry best practices, advantages, limitations, and more.

How can we do the similar distributed processing using Katalon? — I don’t know. I have never seen an article published by Katalon about this issue.

Input by Katalon people is desired.

→ @Elly_Tran , @Shin, @vu.tran

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<div class="post-metadata">

**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [March 23, 2025, 11:05pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/16 "2025-03-23T23:05:38Z")

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> [@vasanthi.jayakumar](#):
>
> at least 4instances should work right

Then, you would want to purchace at least 4 KRE licenses to implement the #2 parallelism. Can you afford of it?

Beware, a license of KRE is payable monthly for fixed amount of money regardless how long seconds/minutes/hours you actually used. It is not a pay-as-you-go system.

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<div class="post-metadata">

**Author:** ![Elly\_Tran](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/elly_tran/32/21874_2.png) [@Elly\_Tran](https://forum.katalon.com/u/Elly_Tran)\
**Post date:** [March 24, 2025, 3:07am UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/18 "2025-03-24T03:07:16Z")

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Hi all,

Thank you for sharing the issue. I will create the ticket for my team to investigate. Back to you soon

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**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [March 24, 2025, 11:25pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/19 "2025-03-24T23:25:23Z")

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> [@vasanthi.jayakumar](#):
>
> Give me some suggestions for faster and better execution ways

I think that the parallel execution of Test Suites is not the first approach you should try for faster and stable test exectuion. Seeking for parallelism would trigger difficult troubles and would waste your time.

Rather, I would recommend you to rewrite each individual test cases so that they run faster and more stable.

For example, if you use “WebUI.delay(n)” keyword in your test cases, you should avoid it. You should replace “WebUI.delay(n)” with “WebUI.waitForElementVisible(testobject, n)”. Why? “WebUI.delay(10)” will always delay your test case for 10 seconds. On the other hand, “WebUI.waitForElementVisible(testobject, 10)” is likely to pass in just 1 seconds. Avoiding “WebUI.delay” will certainly result a faster execution.

You should check the execution log line by line and identify which statement takes long seconds. You should try to find out a way to make it run quickly.

In my humble opinion, there is no automagical way that makes your tests run faster. You need to refactor your test cases one by one. You need to devote yourself for tuning every single test cases to make it run faster and more stable.

When you finished refining all your test cases, a sequential execution of your bulky test suites might run in an acceptable duration. You do not need to pay more money for this approach.

Once you have done fine-tuning your test cases, it would be an idea to try the parallelism #2 for even faster execution while paying for additional multiple machines and additional KRE licenses.

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<div class="post-metadata">

**Author:** ![Elly\_Tran](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/elly_tran/32/21874_2.png) [@Elly\_Tran](https://forum.katalon.com/u/Elly_Tran)\
**Post date:** [March 25, 2025, 3:17am UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/20 "2025-03-25T03:17:22Z")

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Hi,

I got the answer back from my team that If we want to run faster, we should setup Selenium Grid to distribute the test to other machines rather run all tests on the same machine:

> **[Selenium Grid - Execution on Remote Machines with Katalon Studio | Katalon Docs](https://docs.katalon.com/katalon-studio/manage-projects/project-settings/desired-capabilities/selenium-grid---execution-on-remote-machines-with-katalon-studio)**
>
> Katalon Studio allows you to execute your scripts on remote machines by using Selenium Grid.

@vasanthi.jayakumar, please follow up with all the suggestions above. Let us know if any works for you. Otherwise, after 2 weeks no reply from you, I will process to close this. Thank you

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<div class="post-metadata">

**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [March 25, 2025, 10:06am UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/21 "2025-03-25T10:06:06Z")

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> [@Elly\_Tran](#):
>
> I got the answer back from my team that If we want to run faster, we should setup Selenium Grid to distribute the test to other machines rather run all tests on the same machine:

??? I believe that Selenium Grid has nothing to do with the “parallel” execution. I am afraid that the suggestion from the Katalon team does not help @vasanthi.jayakumar. It rather confuses him.

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<div class="post-metadata">

**Author:** ![kazurayam](https://dub1.discourse-cdn.com/katalon/user_avatar/forum.katalon.com/kazurayam/32/333_2.png) [@kazurayam](https://forum.katalon.com/u/kazurayam)\
**Post date:** [April 2, 2025, 9:52pm UTC](https://forum.katalon.com/t/kre-command-line-parallel-headless-mode-execution-not-working/169107/22 "2025-04-02T21:52:17Z")

</div>

> [@kazurayam](#):
>
> How can we do the similar distributed processing using Katalon? — I don’t know. I have never seen an article published by Katalon about this issue.
> 
> Input by Katalon people is desired.
> 
> → @Elly_Tran , @Shin, @vu.tran

The following session might be a response from Katalon.

> [@\[In-person meetup\] Scaling Software Testing with Katalon Runtime Engine and AWS](http://forum.katalon.com/t/in-person-meetup-scaling-software-testing-with-katalon-runtime-engine-and-aws/170129):
>
> [[Main banner (1)] ](https://www.meetup.com/dev-reno/events/306325224/) Let’s meet @andrew.nixdorf1 this Thursday after work in Reno, Nevada us_outlying_islands A Lead SDET at Zywave with more than 5 years of experience in the field of Software Testing, Andrew is a passionate advocate for automation testing. He’s also one of the founding members of /dev/reno: The Reno Developers Meetup and a strong believer in the power of knowledge sharing. Last month, Andrew reviewed the key components of software quality assurance and automated testing us…